Impact of endothelial shear stress on coronary atherosclerotic plaque progression and composition: A meta-analysis and systematic review

BACKGROUND AND AIMS

Intracoronary pressure gradients and translesional flow patterns have been correlated with coronary plaque progression and lesion destabilization. In this study, we aimed to determine the relationship between endothelial shear stress and plaque progression and to evaluate the effect of shear forces on coronary plaque features.

METHODS

A systematic review was conducted in medical on-line databases. Selected were studies including human participants who underwent coronary anatomy assessment with computational fluid dynamics (CFD)-based wall shear stress (WSS) calculation at baseline with anatomical evaluation at follow-up. A total of six studies were included for data extraction and analysis.

RESULTS

The meta-analysis encompassed 31'385 arterial segments from 136 patients. Lower translesional WSS values were significantly associated with a reduction in lumen area (mean difference -0.88, 95% CI -1.13 to -0.62), an increase in plaque burden (mean difference 4.32, 95% CI 1.65 to 6.99), and an increase in necrotic core area (mean difference 0.02, 95% CI 0.02 to 0.03) at follow-up imaging. Elevated WSS values were associated with an increase in lumen area (mean difference 0.78, 95% CI 0.34 to 1.21) and a reduction in both fibrofatty (mean difference -0.02, 95% CI -0.03 to -0.01) and fibrous plaque areas (mean difference -0.03, 95% CI -0.03 to -0.03).

CONCLUSION

This meta-analysis shows that WSS parameters were related to vulnerable plaque features at follow-up. These results emphasize the impact of endothelial shear forces on coronary plaque growth and composition. Future studies are warranted to evaluate the role of WSS in guiding clinical decision-making.

Long-term impact of intravascular ultrasound-guidance for percutaneous coronary intervention on unprotected left main. The IMPACTUS-LM, an observational, multicentric study

INTRODUCTION

The potential benefit on long term outcomes of Percutaneous Coronary Intervention (PCI) on Unprotected Left Main (ULM) driven by IntraVascular UltraSound (IVUS) remains to be defined.

METHODS

IMPACTUS LM-PCI is an observational, multicenter study that enrolled consecutive patients with ULM disease undergoing coronary angioplasty in 13 European high-volume centers from January 2002 to December 2015. Major Adverse Cardiovascular Events (MACEs) a composite of cardiovascular (CV) death, target vessel revascularization (TVR) and myocardial infarction (MI) were the primary endpoints, while its single components along with all cause death the secondary ones.

RESULTS

627 patients with ULM disease were enrolled, 213 patients (34%) underwent IVUS-guided PCI while 414 (66%) angioguided PCI. Patients in the two cohorts had similar prevalence of risk factors except for active smoking and clinical presentation. During a median follow-up of 7.5 years, 47 (22%) patients in the IVUS group and 211 (51%) in the angio-guided group underwent the primary endpoint (HR 0.42; 95% CI [0.31-0.58] p < 0.001). After multivariate adjustment, IVUS was significantly associated with a reduced incidence of the primary endpoint (adj HR 0.39; 95% CI [0.23-0.64], p < 0.001), mainly driven by a reduction of TVR (ad HR 0.30, 95% CI [0.15-0.62], p = 0.001) and of all-cause death (adj HR 0.47, 95% CI [0.28-0.82], p = 0.008). IVUS use, age, diabetes, side branch stenosis, DES and creatinine at admission were independent predictors of MACE.

CONCLUSIONS

In patients undergoing ULM PCI, the use of IVUS was associated with a reduced risk at long-term follow-up of MACE, all-cause death and subsequent revascularization.

A simple coronary CT angiography-based jeopardy score for the identification of extensive coronary artery disease: Validation against invasive coronary angiography

PURPOSE

The invasive British Cardiovascular Intervention Society Jeopardy Score (iBCIS-JS) is a simple angiographic scoring system, enabling quantification of the extent of jeopardized myocardium related to clinically significant coronary artery disease (CAD). The purpose of this study was to develop and validate the coronary CT angiography-based BCIS-JS (CT-BCIS-JS) against the iBCIS-JS in patients with suspected or stable CAD.

MATERIALS AND METHODS

Patients who underwent coronary CT angiography followed by invasive coronary angiography, within 90 days were retrospectively included. CT-BCIS-JS and iBCIS-JS were calculated, with a score ≥ 6 indicating extensive CAD. Correlation between the CT-BCIS-JS and iBCIS-JS was searched for using Spearman's coefficient, and agreement with weighted Kappa (κ) analyses.

RESULTS

A total of 122 patients were included. There were 102 men and 20 women with a median age of 62 years (Q1, Q3: 54, 68; age range: 19-83 years). No differences in median CT-BCIS-JS (4; Q1, Q3: 0, 8) and median iBCIS-JS (4; Q1, Q3: 0, 8) were found (P = 0.18). Extensive CAD was identified in 53 (43.4%) and 52 (42.6%) patients using CT-BCIS-JS and iBCIS-JS, respectively (P = 0.88). CT-based and iBCIS-JS showed excellent correlation (r = 0.98; P < 0.001) and almost perfect agreement (κ = 0.93; 95% confidence interval: 0.90-0.97). Agreement for identification of an iBCIS-JS ≥ 6 was almost perfect (κ = 0.94; 95 % confidence interval: 0.87-0.99).

CONCLUSION

The CT-BCIS-JS represents a feasible, and accurate method for quantification of CAD, with capabilities not different from those of iBCIS-JS. It enables simple, non-invasive identification of patients with anatomically extensive CAD.

A novel score to predict in-hospital mortality for patients with acute coronary syndrome and out-of-hospital cardiac arrest: the FACTOR study

INTRODUCTION

Acute coronary syndromes (ACS) represent a substantial global healthcare challenge. In its most severe form, it can lead to out-of-hospital cardiac arrest (OHCA). Despite medical advancements, survival rates in OHCA patients remain low. Further, the prediction of outcomes in these patients poses a challenge to all health care providers involved. This study aims at developing a score with variables available on admission to assess in-hospital mortality of patients with OHCA undergoing coronary angiography.

METHOD

All patients with OHCA due to ACS admitted to a tertiary care center were included. A multivariate logistic regression analysis was conducted to explore the association between clinical variables and in-hospital all-cause mortality. A scoring system incorporating variables available upon admission to assess individual patients' risk of in-hospital mortality was developed (FACTOR score). The score was then validated.

RESULTS

A total of 291 patients were included in the study, with a median age of 65 [56-73] years, including 47 women (16.2%). The in-hospital mortality rate was 41.2%. A prognostic model was developed in the derivation cohort (n = 138) and included the following variables: age, downtime, first detected rhythm, and administration of epinephrine. The area under the curve for the FACTOR score was 0.823 (95% CI 0.737-0.894) in the derivation cohort and 0.828 (0.760-0.891) in the validation cohort (n = 153).

CONCLUSION

The FACTOR score demonstrated a reliable prognostic tool for health care providers in assessing in-hospital mortality of OHCA patients. Early acknowledgement of a poor prognosis may help in patient management and allocation of resources.

Influence of intracoronary hemodynamic forces on atherosclerotic plaque phenotypes

BACKGROUND AND AIMS

Coronary hemodynamics impact coronary plaque progression and destabilization. The aim of the present study was to establish the association between focal vs. diffuse intracoronary pressure gradients and wall shear stress (WSS) patterns with atherosclerotic plaque composition.

METHODS

Prospective, international, single-arm study of patients with chronic coronary syndromes and hemodynamic significant lesions (fractional flow reserve [FFR] ≤ 0.80). Motorized FFR pullback pressure gradient (PPG), optical coherence tomography (OCT), and time-average WSS (TAWSS) and topological shear variation index (TSVI) derived from three-dimensional angiography were obtained.

RESULTS

One hundred five vessels (median FFR 0.70 [Interquartile range (IQR) 0.56-0.77]) had combined PPG and WSS analyses. TSVI was correlated with PPG (r = 0.47, [95% Confidence Interval (95% CI) 0.30-0.65], p < 0.001). Vessels with a focal CAD (PPG above the median value of 0.67) had significantly higher TAWSS (14.8 [IQR 8.6-24.3] vs. 7.03 [4.8-11.7] Pa, p < 0.001) and TSVI (163.9 [117.6-249.2] vs. 76.8 [23.1-140.9] m-1, p < 0.001). In the 51 vessels with baseline OCT, TSVI was associated with plaque rupture (OR 1.01 [1.00-1.02], p = 0.024), PPG with the extension of lipids (OR 7.78 [6.19-9.77], p = 0.003), with the presence of thin-cap fibroatheroma (OR 2.85 [1.11-7.83], p = 0.024) and plaque rupture (OR 4.94 [1.82 to 13.47], p = 0.002).

CONCLUSIONS

Focal and diffuse coronary artery disease, defined using coronary physiology, are associated with differential WSS profiles. Pullback pressure gradients and WSS profiles are associated with atherosclerotic plaque phenotypes. Focal disease (as identified by high PPG) and high TSVI are associated with high-risk plaque features.

CLINICAL TRIAL REGISTRATION

https://clinicaltrials,gov/ct2/show/NCT03782688.

Head-to-head comparison of two angiography-derived fractional flow reserve techniques in patients with high-risk acute coronary syndrome: A multicenter prospective study

BACKGROUND

FFRangio and QFR are angiography-based technologies that have been validated in patients with stable coronary artery disease. No head-to-head comparison to invasive fractional flow reserve (FFR) has been reported to date in patients with acute coronary syndromes (ACS).

METHODS

This study is a subset of a larger prospective multicenter, single-arm study that involved patients diagnosed with high-risk ACS in whom 30-70% stenosis was evaluated by FFR. FFRangio and QFR - both calculated offline by 2 different and blinded operators - were calculated and compared to FFR. The two co-primary endpoints were the comparison of the Pearson correlation coefficient between FFRangio and QFR with FFR and the comparison of their inter-observer variability.

RESULTS

Among 134 high-risk ACS screened patients, 59 patients with 84 vessels underwent FFR measurements and were included in this study. The mean FFR value was 0.82 ± 0.40 with 32 (38%) being ≤0.80. The mean FFRangio was 0.82 ± 0.20 and the mean QFR was 0.82 ± 0.30, with 27 (32%) and 25 (29%) being ≤0.80, respectively. The Pearson correlation coefficient was significantly better for FFRangio compared to QFR, with R values of 0.76 and 0.61, respectively (p = 0.01). The inter-observer agreement was also significantly better for FFRangio compared to QFR (0.86 vs 0.79, p < 0.05). FFRangio had 91% sensitivity, 100% specificity, and 96.8% accuracy, while QFR exhibited 86.4% sensitivity, 98.4% specificity, and 93.7% accuracy.

CONCLUSION

In patients with high-risk ACS, FFRangio and QFR demonstrated excellent diagnostic performance. FFRangio seems to have better correlation to invasive FFR compared to QFR but further larger validation studies are required.

Association Between Automated 3D Measurement of Coronary Luminal Narrowing and Risk of Future Myocardial Infarction

This study focuses on identifying anatomical markers with predictive capacity for long-term myocardial infarction (MI) in focal coronary artery disease (CAD). Eighty future culprit lesions (FCL) and 108 non-culprit lesions (NCL) from 80 patients underwent 3D quantitative coronary angiography. The minimum lumen area (MLA), minimum lumen ratio (MLR), and vessel fractional flow reserve (vFFR) were evaluated. MLR was defined as the ratio between MLA and the cross-sectional area at the proximal lesion edge, with lower values indicating more abrupt luminal narrowing. Significant differences were observed between FCL and NCL in MLR (0.41 vs. 0.53, p < 0.001). MLR correlated inversely with translesional vFFR (r =  - 0.26, p = 0.0004) and was the strongest predictor of MI at 5 years (AUC = 0.75). Lesions with MLR < 0.40 had a fourfold increased MI incidence at 5 years. MLR is a robust predictor of future adverse coronary events.

Virtual calcium removal in calcified coronary arteries with photon-counting detector CT-first in-vivo experience

Purpose

To evaluate the feasibility and accuracy of quantification of calcified coronary stenoses using virtual non-calcium (VNCa) images in coronary CT angiography (CCTA) with photon-counting detector (PCD) CT compared with quantitative coronary angiography (QCA).

Materials and methods

This retrospective, institutional-review board approved study included consecutive patients with calcified coronary artery plaques undergoing CCTA with PCD-CT and invasive coronary angiography between July and December 2022. Virtual monoenergetic images (VMI) and VNCa images were reconstructed. Diameter stenoses were quantified on VMI and VNCa images by two readers. 3D-QCA served as the standard of reference. Measurements were compared using Bland-Altman analyses, Wilcoxon tests, and intraclass correlation coefficients (ICC).

Results

Thirty patients [mean age, 64 years ± 8 (standard deviation); 26 men] with 81 coronary stenoses from calcified plaques were included. Ten of the 81 stenoses (12%) had to be excluded because of erroneous plaque subtraction on VNCa images. Median diameter stenosis determined on 3D-QCA was 22% (interquartile range, 11%-35%; total range, 4%-88%). As compared with 3D-QCA, VMI overestimated diameter stenoses (mean differences -10%, p < .001, ICC: .87 and -7%, p < .001, ICC: .84 for reader 1 and 2, respectively), whereas VNCa images showed similar diameter stenoses (mean differences 0%, p = .68, ICC: .94 and 1%, p = .07, ICC: .93 for reader 1 and 2, respectively).

Conclusion

First experience in mainly minimal to moderate stenoses suggests that virtual calcium removal in CCTA with PCD-CT, when feasible, has the potential to improve the quantification of calcified stenoses.

Blood Flow Energy Identifies Coronary Lesions Culprit of Future Myocardial Infarction

The present study establishes a link between blood flow energy transformations in coronary atherosclerotic lesions and clinical outcomes. The predictive capacity for future myocardial infarction (MI) was compared with that of established quantitative coronary angiography (QCA)-derived predictors. Angiography-based computational fluid dynamics (CFD) simulations were performed on 80 human coronary lesions culprit of MI within 5 years and 108 non-culprit lesions for future MI. Blood flow energy transformations were assessed in the converging flow segment of the lesion as ratios of kinetic and rotational energy values (KER and RER, respectively) at the QCA-identified minimum lumen area and proximal lesion sections. The anatomical and functional lesion severity were evaluated with QCA to derive percentage area stenosis (%AS), vessel fractional flow reserve (vFFR), and translesional vFFR (ΔvFFR). Wall shear stress profiles were investigated in terms of topological shear variation index (TSVI). KER and RER predicted MI at 5 years (AUC = 0.73, 95% CI 0.65-0.80, and AUC = 0.76, 95% CI 0.70-0.83, respectively; p < 0.0001 for both). The predictive capacity for future MI of KER and RER was significantly stronger than vFFR (p = 0.0391 and p = 0.0045, respectively). RER predictive capacity was significantly stronger than %AS and ΔvFFR (p = 0.0041 and p = 0.0059, respectively). The predictive capacity for future MI of KER and RER did not differ significantly from TSVI. Blood flow kinetic and rotational energy transformations were significant predictors for MI at 5 years (p < 0.0001). The findings of this study support the hypothesis of a biomechanical contribution to the process of plaque destabilization/rupture leading to MI.

Higher 1-year mortality on rest days in patients with acute coronary syndromes and decompensated heart failure-A SPUM-ACS sub-study

BACKGROUND

Acute coronary syndromes (ACS) occurring on rest days have been associated with higher mortality, but the current literature remains inconsistent in this regard. This study included ACS patients presenting with acute decompensated heart failure (ADHF) investigating the relationship between time of coronary catheterization and outcomes.

METHODS

Analyses were performed from the prospective, multicentric Special Program University Medicine Acute Coronary Syndromes and Inflammation (SPUM-ACS) Cohort. Patients were divided into two groups according to time of coronary catheterization on either workdays (Monday, 00:00 to Friday, 23:59) or rest days (Saturday, 00:00 to Sunday, 23:59 and public holidays). ADHF was defined by Killip Class III or IV upon presentation. Patients were followed over 1 year.

RESULTS

Out of 4787 ACS patients enrolled in the SPUM-ACS Cohort, 207 (4.3%) presented with ADHF. 52 (25.1%) and 155 (74.9%) patients underwent coronary angiography on rest days or workdays, respectively. Baseline characteristics were similar among these groups. ACS patients with ADHF showed increased 1-year mortality on rest days (34.6% vs. 17.4%, p-value = 0.009). After correction for baseline characteristics, including the GRACE 2.0 Score, rest day presentation remained a significant predictor for 1-year mortality (adjusted hazard ratio = 2.42 [95% confidence interval: 1.14-5.17], p-value = 0.022).

CONCLUSIONS

One-year all-cause mortality was high in ACS patients with ADHF and doubled for patients admitted on rest days. The present data support the association of a rest day effect and long-term patient survival and indicate a need for further investigations.

Twenty-five-year trends in incidence, angiographic appearance, and management of spontaneous coronary artery dissection

BACKGROUND

Spontaneous coronary artery dissection (SCAD) has been described as an infrequent cause of acute coronary syndrome (ACS). Knowledge about the disease is still limited and SCAD might still be underdiagnosed.

OBJECTIVES

Trends in incidence, presentation, angiographic appearance, management, and outcomes of SCAD over 25 years were analyzed.

METHODS

Patients with SCAD between 1997 and 2021 at the University Hospital Zurich, Switzerland, were included. Incidences were assessed as total numbers and proportions of ACS cases. Clinical data were collected from medical records and angiographic findings were reviewed. Major adverse cardiac events (MACE) were defined as the composite of all-cause death, cardiac arrest, SCAD recurrence or progression, other myocardial infarction, and stroke.

RESULTS

One hundred fifty-six SCAD cases were included in this study. The incidence increased significantly in total (p < 0.001) and relative to ACS cases (p < 0.001). This was based on an increase of shorter lesions (p = 0.004), SCAD type 2 (p < 0.001), and lesions in side branches (p = 0.014), whereas lesions in the left main coronary artery and proximal segments were decreasing (p-values 0.029 and < 0.001, respectively). There was an increase in conservative therapy (p < 0.001). The rate of MACE (24%) was stable, however, there was a reduced proportion of patients with a need for intensive care treatment (p = 0.017).

CONCLUSIONS

SCAD represents an important entity of ACS that still might be underappreciated. The increasing incidence of SCAD is likely based on better awareness and familiarity with the disease. A lower need for intensive care treatment suggests positive effects of the increasing implementation of conservative management.

Bicuspid Aortic Valve Disease: Classifications, Treatments, and Emerging Transcatheter Paradigms

Bicuspid aortic valve (BAV) is a common congenital valvular malformation, which may lead to early aortic valve disease and bicuspid-associated aortopathy. A novel BAV classification system was recently proposed to coincide with transcatheter aortic valve replacement being increasingly considered in younger patients with symptomatic BAV, with good clinical results, yet without randomized trial evidence. Procedural technique, along with clinical outcomes, have considerably improved in BAV patients compared with tricuspid aortic stenosis patients undergoing transcatheter aortic valve replacement. The present review summarizes the novel BAV classification systems and examines contemporary surgical and transcatheter approaches.

Modelling blood flow in coronary arteries: Newtonian or shear-thinning non-Newtonian rheology?

BACKGROUND

The combination of medical imaging and computational hemodynamics is a promising technology to diagnose/prognose coronary artery disease (CAD). However, the clinical translation of in silico hemodynamic models is still hampered by assumptions/idealizations that must be introduced in model-based strategies and that necessarily imply uncertainty. This study aims to provide a definite answer to the open question of how to properly model blood rheological properties in computational fluid dynamics (CFD) simulations of coronary hemodynamics.

METHODS

The geometry of the right coronary artery (RCA) of 144 hemodynamically stable patients with different stenosis degree were reconstructed from angiography. On them, unsteady-state CFD simulations were carried out. On each reconstructed RCA two different simulation strategies were applied to account for blood rheological properties, implementing (i) a Newtonian (N) and (ii) a shear-thinning non-Newtonian (non-N) rheological model. Their impact was evaluated in terms of wall shear stress (WSS magnitude, multidirectionality, topological skeleton) and helical flow (strength, topology) profiles. Additionally, luminal surface areas (SAs) exposed to shear disturbances were identified and the co-localization of paired N and non-N SAs was quantified in terms of similarity index (SI).

RESULTS

The comparison between paired N vs. shear-thinning non-N simulations revealed remarkably similar profiles of WSS-based and helicity-based quantities, independent of the adopted blood rheology model and of the degree of stenosis of the vessel. Statistically, for each paired N and non-N hemodynamic quantity emerged negligible bias from Bland-Altman plots, and strong positive linear correlation (r > 0.94 for almost all the WSS-based quantities, r > 0.99 for helicity-based quantities). Moreover, a remarkable co-localization of N vs. non-N luminal SAs exposed to disturbed shear clearly emerged (SI distribution 0.95 [0.93, 0.97]). Helical flow topology resulted to be unaffected by blood rheological properties.

CONCLUSIONS

This study, performed on 288 angio-based CFD simulations on 144 RCA models presenting with different degrees of stenosis, suggests that the assumptions on blood rheology have negligible impact both on WSS and helical flow profiles associated with CAD, thus definitively answering to the question "is Newtonian assumption for blood rheology adequate in coronary hemodynamics simulations?".

Continuous vs Bolus Thermodilution to Assess Microvascular Resistance Reserve

BACKGROUND

Coronary flow reserve (CFR) and microvascular resistance reserve (MRR) can, in principle, be derived by any method assessing coronary flow.

OBJECTIVES

The aim of this study was to compare CFR and MRR as derived by continuous (CFRcont and MRRcont) and bolus thermodilution (CFRbolus and MRRbolus).

METHODS

A total of 175 patients with chest pain and nonobstructive coronary artery disease were studied. Bolus and continuous thermodilution measurements were performed in the left anterior descending coronary artery. MRR was calculated as the ratio of CFR to fractional flow reserve and corrected for changes in systemic pressure. In 102 patients, bolus and continuous thermodilution measurements were performed in duplicate to assess test-retest reliability.

RESULTS

Mean CFRbolus was higher than CFRcont (3.47 ± 1.42 and 2.67 ± 0.81 [P < 0.001], mean difference 0.80, upper limit of agreement 3.92, lower limit of agreement -2.32). Mean MRRbolus was also higher than MRRcont (4.40 ± 1.99 and 3.22 ± 1.02 [P < 0.001], mean difference 1.2, upper limit of agreement 5.08, lower limit of agreement -2.71). The correlation between CFR and MRR values obtained using both methods was significant but weak (CFR, r = 0.28 [95% CI: 0.14-0.41]; MRR, r = 0.26 [95% CI: 0.16-0.39]; P < 0.001 for both). The precision of both CFR and MRR was higher when assessed using continuous thermodilution compared with bolus thermodilution (repeatability coefficients of 0.89 and 2.79 for CFRcont and CFRbolus, respectively, and 1.01 and 3.05 for MRRcont and MRRbolus, respectively).

CONCLUSIONS

Compared with bolus thermodilution, continuous thermodilution yields lower values of CFR and MRR accompanied by an almost 3-fold reduction of the variability in the measured results.

Coronary microvascular dysfunction in Takotsubo syndrome: an analysis using angiography-derived index of microcirculatory resistance

BACKGROUND

Coronary microvascular dysfunction (CMD) has been proposed as a crucial factor in the pathophysiology of Takotsubo syndrome (TTS). The angiography-derived index of microcirculatory resistance (caIMR) offers an alternative to conventional hyperemic wire-based IMR to assess CMD. We aimed to evaluate CMD's prevalence, transience, and impact on in-hospital outcomes in TTS.

METHODS

All three coronary arteries of 96 patients with TTS were assessed for their coronary angiography derived Index of microcirculatory Resistance (caIMR) and compared to non-obstructed vessels of matched patients with ST-elevation myocardial infarction. Further, the association between caIMR and the TTS-specific combined in-hospital endpoint of death, cardiac arrest, ventricular arrhythmogenic events and cardiogenic shock was investigated.

RESULTS

Elevated IMR was present in all TTS patients, with significantly elevated caIMR values in all coronary arteries compared to controls. CaIMR did not differ between apical and midventricular TTS types. CaIMR normalized in TTS patients with follow-up angiographies performed at a median of 28 months (median caIMR at event vs follow-up: LAD 34.8 [29.9-41.1] vs 20.3 [16.0-25.3], p < 0.001; LCX: 38.7 [32.9-50.1] vs 23.7 [19.4-30.5], p < 0.001; RCA: 31.7 [25.0-39.1] vs 19.6 [17.1-24.0], p < 0.001). The extent of caIMR elevation significantly correlated with the combined in-hospital endpoint (p = 0.036).

CONCLUSION

TTS patients had evidence of elevated caIMR in at least one coronary artery with a trend towards higher LAD caIMR in apical type TTS and normalization after recovery. Furthermore, extent of caIMR elevation was associated with increased risk of in-hospital MACE of TTS patients.

Timing of Complete Revascularization with Multivessel PCI for Myocardial Infarction

BACKGROUND

In patients with ST-segment elevation myocardial infarction (STEMI) with multivessel coronary artery disease, the time at which complete revascularization of nonculprit lesions should be performed remains unknown.

METHODS

We performed an international, open-label, randomized, noninferiority trial at 37 sites in Europe. Patients in a hemodynamically stable condition who had STEMI and multivessel coronary artery disease were randomly assigned to undergo immediate multivessel percutaneous coronary intervention (PCI; immediate group) or PCI of the culprit lesion followed by staged multivessel PCI of nonculprit lesions within 19 to 45 days after the index procedure (staged group). The primary end point was a composite of death from any cause, nonfatal myocardial infarction, stroke, unplanned ischemia-driven revascularization, or hospitalization for heart failure at 1 year after randomization. The percentages of patients with a primary or secondary end-point event are provided as Kaplan-Meier estimates at 6 months and at 1 year.

RESULTS

We assigned 418 patients to undergo immediate multivessel PCI and 422 to undergo staged multivessel PCI. A primary end-point event occurred in 35 patients (8.5%) in the immediate group as compared with 68 patients (16.3%) in the staged group (risk ratio, 0.52; 95% confidence interval, 0.38 to 0.72; P<0.001 for noninferiority and P<0.001 for superiority). Nonfatal myocardial infarction and unplanned ischemia-driven revascularization occurred in 8 patients (2.0%) and 17 patients (4.1%), respectively, in the immediate group and in 22 patients (5.3%) and 39 patients (9.3%), respectively, in the staged group. The risk of death from any cause, the risk of stroke, and the risk of hospitalization for heart failure appeared to be similar in the two groups. A total of 104 patients in the immediate group and 145 patients in the staged group had a serious adverse event.

CONCLUSIONS

Among patients in hemodynamically stable condition with STEMI and multivessel coronary artery disease, immediate multivessel PCI was noninferior to staged multivessel PCI with respect to the risk of death from any cause, nonfatal myocardial infarction, stroke, unplanned ischemia-driven revascularization, or hospitalization for heart failure at 1 year. (Supported by Boston Scientific; MULTISTARS AMI ClinicalTrials.gov number, NCT03135275.).

MINOCA Associated with a Myocardial Bridge: Pathogenesis, Diagnosis and Treatment

Myocardial bridging (MB) is the most frequent congenital coronary anomaly characterized by a segment of an epicardial coronary artery that passes through the myocardium. MB is an important cause of myocardial ischemia and is also emerging as a possible cause of myocardial infarction with non-obstructed coronary arteries (MINOCA). There are multiple mechanisms underlying MINOCA in patients with MB (i.e., MB-mediated increased risk of epicardial or microvascular coronary spasm, atherosclerotic plaque disruption and spontaneous coronary artery dissection). The identification of the exact pathogenetic mechanism is crucial in order to establish a patient-tailored therapy. This review provides the most up-to-date evidence regarding the pathophysiology of MINOCA in patients with MB. Moreover, it focuses on the available diagnostic tools that could be implemented at the time of coronary angiography to achieve a pathophysiologic diagnosis. Finally, it focuses on the therapeutic implications associated with the different pathogenetic mechanisms of MINOCA in patients with MB.

Is spontaneous coronary artery dissection (SCAD) related to local anatomy and hemodynamics? An exploratory study

AIMS

Spontaneous coronary artery dissection (SCAD) is an increasingly diagnosed cause of myocardial infarction with unclear pathophysiology. The aim of the study was to test if vascular segments site of SCAD present distinctive local anatomy and hemodynamic profiles.

METHODS

Coronary arteries with spontaneously healed SCAD (confirmed by follow-up angiography) underwent three-dimensional reconstruction, morphometric analysis with definition of vessel local curvature and torsion, and computational fluid dynamics (CFD) simulations with derivation of time-averaged wall shear stress (TAWSS) and topological shear variation index (TSVI). The (reconstructed) healed proximal SCAD segment was visually inspected for co-localization with curvature, torsion, and CFD-derived quantities hot spots.

RESULTS

Thirteen vessels with healed SCAD underwent the morpho-functional analysis. Median time between baseline and follow-up coronary angiograms was 57 (interquartile range [IQR] 45-95) days. In seven cases (53.9%), SCAD was classified as type 2b and occurred in the left anterior descending artery or near a bifurcation. In all cases (100%), at least one hot spot co-localized within the healed proximal SCAD segment, in 9 cases (69.2%) ≥3 hot spots were identified. Healed SCAD in proximity of a coronary bifurcation presented lower TAWSS peak values (6.65 [IQR 6.20-13.2] vs. 3.81 [2.53-5.17] Pa, p = 0.008) and hosted less frequently TSVI hot spots (100% vs. 57.1%, p = 0.034).

CONCLUSION

Vascular segments of healed SCAD were characterized by high curvature/torsion and WSS profiles reflecting increased local flow disturbances. Hence, a pathophysiological role of the interaction between vessel anatomy and shear forces in SCAD is hypothesized.

Reproducibility of bolus versus continuous thermodilution for assessment of coronary microvascular function in patients with ANOCA

BACKGROUND

A bolus thermodilution-derived index of microcirculatory resistance (IMR) has emerged as the standard for assessing coronary microvascular dysfunction (CMD). Continuous thermodilution has recently been introduced as a tool to quantify absolute coronary flow and microvascular resistance directly. Microvascular resistance reserve (MRR) derived from continuous thermodilution has been proposed as a novel metric of microvascular function, which is independent of epicardial stenoses and myocardial mass.

AIMS

We aimed to assess the reproducibility of bolus and continuous thermodilution in assessing coronary microvascular function.

METHODS

Patients with angina and non-obstructive coronary artery disease (ANOCA) at angiography were prospectively enrolled. Bolus and continuous intracoronary thermodilution measurements were obtained in duplicate in the left anterior descending artery (LAD). Patients were randomly assigned in a 1:1 ratio to undergo either bolus thermodilution first or continuous thermodilution first.

RESULTS

A total of 102 patients were enrolled. The mean fractional flow reserve (FFR) was 0.86±0.06. Coronary flow reserve (CFR) calculated with continuous thermodilution (CFR_cont) was significantly lower than bolus thermodilution-derived CFR (CFR_bolus; 2.63±0.65 vs 3.29±1.17; p<0.001). CFR_cont showed a higher reproducibility than CFR_bolus (variability: 12.7±10.4% continuous vs 31.26±24.85% bolus; p<0.001). MRR showed a higher reproducibility than IMR (variability 12.4±10.1% continuous vs 24.2±19.3% bolus; p<0.001). No correlation was found between MRR and IMR (r=0.1, 95% confidence interval: -0.09 to 0.29; p=0.305).

CONCLUSIONS

In the assessment of coronary microvascular function, continuous thermodilution demonstrated significantly less variability on repeated measurements than bolus thermodilution.

Effectiveness of radiation protection systems in the cardiac catheterization laboratory: a comparative study

BACKGROUND

As numbers and complexity of percutaneous coronary interventions are constantly increasing, optimal radiation protection is required to ensure operator safety. Suspended radiation protection systems (SRPS) and protective scatter-radiation absorbing drapes (PAD) are novel methods to mitigate fluoroscopic scattered radiation exposure. The aim of the study was to investigate the effectiveness regarding radiation protection of a SRPS and a PAD in comparison with conventional protection.

METHODS

A total of 229 cardiac catheterization procedures with SRPS (N = 73), PAD (N = 82) and standard radiation protection (N = 74) were prospectively included. Real-time dosimeter data were collected from the first operator and the assistant. Endpoints were the cumulative operator exposure relative to the dose area product [standardized operator exposure (SOE)] for the first operator and the assistant.

RESULTS

For the first operator, the SRPS and the PAD significantly decreased the overall SOE compared to conventional shielding by 93.9% and 66.4%, respectively (P < 0.001). The protective effect of the SRPS was significantly higher compared to the PAD (P < 0.001). For the assistant, the SRPS and the PAD provided a not statistically significant reduction compared to conventional shielding in the overall SOE by 38.0% and 30.6%, respectively.

CONCLUSIONS

The SRPS and the PAD enhance radiation protection significantly compared to conventional protection. In most clinical scenarios, the protective effect of SRPS is significantly higher than the additional protection provided by the PAD. Comparison of the additional radiation protection provided by protective scatter-radiation absorbing drapes (PAD) and the suspended radiation protection system (SRPS) system over standard protection with lead aprons.

[Angina Pectoris and the Importance of Coronary Microcirculation in Practice]

Angina Pectoris and the Importance of Coronary Microcirculation in Practice Abstract. Microvascular angina is a common manifestation of coronary microvascular dysfunction, particulary prevalent in post-menopausal women above the age of 50 and associated with impaired quality of life and poor clinical outcomes. However, microvascular angina remains largely undetected given the underuse of diagnostic tools for the assessment of coronary microvascular function. As a consequence, many of these patients suffering from coronary microvascular dysfunction fail to receive the appropriate medical treatment and remain in the long term symptomatic. Invasive coronary catheterization with measurement of coronary flow reserve and intracoronary acetylcholine provocation testing allows for the assessment of coronary microvascular dysfunction, and a therapy targeting specific physiological pathways can be implemented. A targeted therapy includes lifestyle modifications, secondary prevention measures, and anti-anginal medication. Ongoing clinical research in the field is expected to deliver novel diagnostic and therapeutic concepts for an improved management of patients with coronary microvascular disease.

840 ASSESSMENT OF ABSOLUTE CORONARY FLOW AND MICROVASCULAR RESISTANCE RESERVE IN PATIENTS WITH AORTIC STENOSIS

Introduction

The development of left ventricular hypertrophy in patients with severe aortic stenosis (AS) is accompanied by adaptive coronary flow regulation, both in epicardial and microvascular compartment, which ultimately lead to a chronic ischemic insult even in the absence of obstructive coronary artery disease. Intracoronary continuous thermodilution of saline through a dedicated infusion catheter (RayFlow ®) is a novel tool that allows to measure absolute coronary flow and microvascular resistance at rest and during hyperemia and to calculate both coronary flow reserve (CFR) and Microvascular Resistance Reserve (MRR)

Purpose

We aimed to assess absolute coronary flow, microvascular resistance, CFR and MRR in patients with AS, assessed by continuous intracoronary thermodilution, comparing these hemodynamic findings with a propensity-score matched contemporary cohort of patients without AS.

Methods

Absolute coronary blood flow and microvascular resistance were measured by continuous thermodilution in 29 patients with AS and compared to 15 controls matched for age, gender, diabetes mellitus and functional severity of epicardial coronary lesions. Myocardial work, total myocardial mass and LAD-specific mass were quantified by echocardiography and cardiac-CT.

Results

Patients with AS presented a significantly positive LV remodeling with lower global longitudinal strain and higher global work index compared to controls (p&lt;0.02). Total LV myocardial mass and LAD-specific myocardial mass were significantly higher in patients with AS. Compared to matched controls, absolute resting flow in the LAD was significantly higher in the AS cohort (86 [66–107] ml/min vs 68 [52–75] ml/min, p=0.036), resulting, in lower CFR (2.30 ± 0.69 vs 2.89 ± 0.77, p=0.005) and MRR (2.73 ± 0.74 vs 3.53 ± 0.95, p=0.005) in the AS cohort compared to controls (Figure 1). No differences were found in hyperemic flow and resting and hyperemic resistances. Interestingly, hyperemic myocardial perfusion (calculated as the ratio between the absolute coronary flow subtended to the LAD and expressed in mL/min/g), but not resting, was significantly lower in the AS group (1.9 [1.5–2.5] ml/min/g vs 2.3 [2–3.1] ml/min/g p=0.036).

Conclusions

In patients with severe aortic stenosis and non-obstructive coronary artery disease, with the progression of LVH, the compensatory mechanism of increased resting flow maintains an adequate perfusion at rest, but not during hyperemia (Figure 2). As consequence, both CFR and MRR are significantly impaired.

Absolute coronary flow and microvascular resistance reserve in patients with severe aortic stenosis

BACKGROUND

Development of left ventricle (LV) hypertrophy in aortic stenosis (AS) is accompanied by adaptive coronary flow regulation. We aimed to assess absolute coronary flow, microvascular resistance, coronary flow reverse (CFR) and microvascular resistance reserve (MRR) in patients with and without AS.

METHODS

Absolute coronary flow and microvascular resistance were measured by continuous thermodilution in 29 patients with AS and 29 controls, without AS, matched for age, gender, diabetes and functional severity of epicardial coronary lesions. Myocardial work, total myocardial mass and left anterior descending artery (LAD)-specific mass were quantified by echocardiography and cardiac-CT.

RESULTS

Patients with AS presented a significantly positive LV remodelling with lower global longitudinal strain and global work efficacy compared with controls. Total LV myocardial mass and LAD-specific myocardial mass were significantly higher in patients with AS (p=0.001). Compared with matched controls, absolute resting flow in the LAD was significantly higher in the AS cohort (p=0.009), resulting into lower CFR and MRR in the AS cohort compared with controls (p<0.005 for both). No differences were found in hyperaemic flow and resting and hyperaemic resistances. Hyperaemic myocardial perfusion (calculated as the ratio between the absolute coronary flow subtended to the LAD, expressed in mL/min/g), but not resting, was significantly lower in the AS group (p=0.035).

CONCLUSIONS

In patients with severe AS and non-obstructive coronary artery disease, with the progression of LV hypertrophy, the compensatory mechanism of increased resting flow maintains adequate perfusion at rest, but not during hyperaemia. As a consequence, both CFR and MRR are significantly impaired.

Assessment of absolute coronary flow and microvascular resistance reserve in patients with severe aortic stenosis

Introduction

The development of left ventricular hypertrophy in patients with severe aortic stenosis (AS) is accompanied by adaptive coronary flow regulation, both in epicardial and microvascular compartment, which ultimately lead to a chronic ischemic insult even in the absence of obstructive coronary artery disease. Intracoronary continuous thermodilution of saline through a dedicated infusion catheter is a novel tool that allows to measure absolute coronary flow and microvascular resistance at rest and during hyperemia and to calculate both coronary flow reserve (CFR) and Microvascular Resistance Reserve (MRR)

Purpose

We aimed to assess absolute coronary flow, microvascular resistance, CFR and MRR in patients with AS, by continuous intracoronary thermodilution, comparing these hemodynamic findings with a propensity-score matched contemporary cohort of patients without AS.

Methods

Absolute coronary blood flow and microvascular resistance were measured by continuous thermodilution in 29 patients with AS and compared to 15 controls matched for age, gender, diabetes mellitus and functional severity of epicardial coronary lesions. Myocardial work, total myocardial mass and LAD-specific mass were quantified by echocardiography and cardiac-CT.

Results

Patients with AS presented a significantly positive LV remodeling with lower global longitudinal strain and higher global work index compared to controls (p&lt;0.02). Total LV myocardial mass and LAD-specific myocardial mass were significantly higher in patients with AS. Compared to matched controls, absolute resting flow in the LAD was significantly higher in the AS cohort (86 [66–107] ml/min vs 68 [52–75] ml/min, p=0.036), resulting, in lower CFR (2.30±0.69 vs 2.89±0.77, p=0.005) and MRR (2.73±0.74 vs 3.53±0.95, p=0.005) in the AS cohort compared to controls (Figure 1). No differences were found in hyperemic flow and resting and hyperemic resistances. Interestingly, hyperemic myocardial perfusion (calculated as the ratio between the absolute coronary flow in the LAD and the mass subtended by the vessel, expressed in mL/min/g), but not resting, was significantly lower in the AS group (1.9 [1.5–2.5] ml/min/g vs 2.3 [2–3.1] ml/min/g p=0.036).

Conclusions

In patients with severe aortic stenosis and non-obstructive coronary artery disease, with the progression of LVH, the compensatory mechanism of increased resting flow maintains an adequate perfusion at rest, but not during hyperemia (Figure 2). As consequence, both CFR and MRR are significantly impaired.

Funding Acknowledgement

Type of funding sources: None.

Outcomes of patients presenting with acute coronary syndromes on workdays vs. rest days (SPUM-ACS substudy)

Introduction

Conflicting data exist upon whether patients presenting with acute coronary syndromes (ACS) during on- or off-hours differ regarding outcomes. Moreover, definitions of on- and off-hours vary in literature. The notion of a weekend effect with increased mortality has been raised, mostly seen in relation to lesser use of invasive treatment.

Purpose

This multi-center study investigated the baseline characteristics and associated outcomes of patients presenting with ACS undergoing coronary angiography on weekdays compared to those presenting on weekends or holidays.

Methods

Data from the prospective SPUM-ACS (Special Program University Medicine Acute Coronary Syndromes and Inflammation) Cohort were examined, with patients recruited between 2009 and 2012. Patients were divided into two groups according to whether they presented for coronary angiography for ACS on workdays (Monday-Friday, 00:00–23:59) or on rest days (Saturday or Sunday, 00:00–23:59, and public holidays shared by all centers). Time of presentation was defined as time point of catheter sheath insertion.

Results

From a total of 2168 patients (21.4% females), 1828 (84.3%) presented on workdays, 340 (15.7%) on rest days without difference in female/male ratio. On rest days, patients more often showed signs of advanced heart failure (Killip Class III–IV 3.9% vs. 7.1%, p=0.009). Patients presented more frequently with ST-segment elevation ACS (STE-ACS) than non-ST-segment elevation ACS (STE-ACS on workdays vs. rest days: 50.4% vs. 65.0%, p&lt;0.001).

In- and out-of-hospital time delay metrics did not differ between groups, apart from symptom onset-to-balloon time, which was shorter on rest days (598 vs. 520 min, p=0.040). There was a trend towards more frequent use of percutaneous (89.2% vs. 92.6%, p=0.053) or surgical (3.3% vs 5.0%, p=0.131) revascularization on rest days.

30-day all-cause mortality was higher on rest days for any ACS (1.75% vs 3.82%, p=0.007) and for STE-ACS only (2.39% vs 4.98%, p=0.019, Fig. 1). Notably, the same trend was seen when comparing only patients presenting with Killip Class III/IV, both for any ACS (11.27% vs. 20.83%, p=0.119) and for STE-ACS (14.00% vs. 26.32%, p=0.114). On rest days, female patients showed higher 30-day all-cause mortality than males for any ACS (7.46% vs 2.93%, p=0.042); the same trend was observed for STE-ACS (8.89% vs. 3.98%, p=0.088).

Conclusions

On rest days, patients more often presented with STE-ACS and more frequently showed signs of advanced heart failure, with similar use of invasive revascularization as for patients presenting on workdays. This might contribute to higher early mortality observed in ACS patients on rest days. These differences persisted within the subgroups STE-ACS and Killip Class III/IV. Interestingly, female patients showed increased early mortality on rest days compared to males. Thus, patients presenting with ACS on rest days warrant particular attention.

Funding Acknowledgement

Type of funding sources: Public grant(s) – National budget only. Main funding source(s): Swiss National Science Foundation (SNSF)

Repeatability of bolus and continuous thermodilution for assessing coronary microvasculatory function

Introduction

The bolus thermodilution-derived index of microcirculatory resistance (IMR) has emerged over years as the standard of reference to invasively define coronary microvascular dysfunction (CMD). However, the technique still presents some limitations, mainly related to the fact that manual injection of saline bolus accounts for some variance in the measurements. Continuous intracoronary thermodilution has been recently introduced as a tool to directly quantify absolute coronary flow and microvascular resistance both at rest and during hyperemia and has shown to be safe and operator independent. Microvascular resistance reserve (MRR), derived from continuous thermodilution, has been validated as novel index specific for microcirculation and independent from myocardial mass.

Purpose

To compare head-to-head the intra-observer repeatability of bolus and continuous thermodilution for assessing microvascular function.

Methods

Patients undergoing coronary angiography in the absence of obstructive coronary artery disease were prospectively enrolled. Bolus and continuous intracoronary thermodilution measurements were performed in duplicates in the left anterior descending artery (LAD). Patients were randomly assigned in a 1:1 ratio to undergo first bolus thermodilution or first continuous thermodilution assessment.

Results

A total of 102 patients were enrolled. Average FFR was 0.86±0.06. Coronary Flow Reserve (CFR) calculated with continuous thermodilution (CFRthermo) was significantly lower than bolus thermodilution-derived CFR (CFRbolus) (2.63±0.65 and 3.29±1.17, respectively, p&lt;0.001). CFRthermo showed a lower variability and a higher agreement than CFRbolus (variability 12.74±10.41% vs 31.26±24.85%, respectively, p&lt;0.001; ICC= 0.78 (0.70–0.85) and 0.48 (0.32–0.62), respectively, p&lt;0.001, Figure 1). Both MRR and IMR showed a good agreement (ICC 0.81 (0.74–0.87) and 0.80 (0.71–0.86)) but the variability of the MRR was significantly lower (12.44±10.06% vs 24.24±19.27, respectively, p&lt;0.001, Figure 1). Reproducibility data of all indices derived from duplicated measurements of bolus and continuous thermodilution are reported in Table 2.

Conclusion

Continuous intracoronary thermodilution has a higher repeatability than bolus thermodilution in the assessment of CMD.

Funding Acknowledgement

Type of funding sources: None.

Saline-induced coronary hyperemia with continuous intracoronary thermodilution is mediated by intravascular hemolysis

Objectives

To test whether local hemolysis is a potential mechanism of saline-induced coronary hyperemia.

Background

Absolute coronary flow can be measured by intracoronary continuous thermodilution of saline through the lateral side holes of a dedicated infusion cathete. A saline infusion rate at 15–20 mL/min induces an immediate, steady-state, maximal microvascular vasodilation. The mechanism of this hyperemic response remains unclear.

Methods

Twelve patients undergoing left and right catheterization were included. The left coronary artery and the coronary sinus were selectively cannulated. Absolute resting and hyperemic coronary flow were measured by continuous intracoronary thermodilution. Arterial and venous samples were collected from the coronary artery and the coronary sinus in five phases: baseline (BL); resting flow measurement (Rest, saline infusion at 10 mL/min); hyperemia (Hyperemia,saline infusion at 20 mL/min); post-hyperemia (Post-Hyperemia, two minutes after the cessation of saline infusion); and control phase (Control, during infusion of saline through the guide catheter at 30 mL/min).

Results

Hemolysis was visually detected only in the centrifugated venous blood samples collected during the Hyperemia phase. As compared to Rest, during Hyperemia both LDH (131.50±21.89 U/dL [Rest] and 258.33±57.40 U/dL [Hyperemia], p&lt;0.001) and plasma free hemoglobin (PFHb, 4.92±3.82 mg/dL [Rest] and 108.42±46.58 mg/dL [Hyperemia], p&lt;0.001) significantly increased in the coronary sinus. The percentage of hemolysis was significantly higher during the Hyperemia phase (0.04±0.02% [Rest] vs 0.89±0.34% [Hyperemia], p&lt;0.001).

Conclusions

Saline-induced hyperemia through a dedicated intracoronary infusion catheter is associated with hemolysis. Vasodilatory compounds released locally, like ATP, are likely ultimately responsible for localized microvascular vasodilation.

Funding Acknowledgement

Type of funding sources: None.

Deferral of Coronary Revascularization in Patients With Reduced Ejection Fraction Based on Physiological Assessment: Impact on Long-Term Survival

Background Deferring revascularization in patients with nonsignificant stenoses based on fractional flow reserve (FFR) is associated with favorable clinical outcomes up to 15 years. Whether this holds true in patients with reduced left ventricular ejection fraction is unclear. We aimed to investigate whether FFR provides adjunctive clinical benefit compared with coronary angiography in deferring revascularization of patients with intermediate coronary stenoses and reduced left ventricular ejection fraction. Methods and Results Consecutive patients with reduced left ventricular ejection fraction (≤50%) undergoing coronary angiography between 2002 and 2010 were screened. We included patients with at least 1 intermediate coronary stenosis (diameter stenosis ≥40%) in whom revascularization was deferred based either on angiography plus FFR (FFR guided) or angiography alone (angiography guided). The primary end point was the cumulative incidence of all-cause death at 10 years. The secondary end point (incidence of major adverse cardiovascular and cerebrovascular events) was a composite of all-cause death, myocardial infarction, any revascularization, and stroke. A total of 840 patients were included (206 in the FFR-guided group and 634 in the angiography-guided group). Median follow-up was 7 years (interquartile range, 3.22-11.08 years). After 1:1 propensity-score matching, baseline characteristics between the 2 groups were similar. All-cause death was significantly lower in the FFR-guided group compared with the angiography-guided group (94 [45.6%] versus 119 [57.8%]; hazard ratio [HR], 0.65 [95% CI, 0.49-0.85]; P<0.01). The rate of major adverse cardiovascular and cerebrovascular events was lower in the FFR-guided group (123 [59.7%] versus 139 [67.5%]; HR, 0.75 [95% CI, 0.59-0.95]; P=0.02). Conclusions In patients with reduced left ventricular ejection fraction, deferring revascularization of intermediate coronary stenoses based on FFR is associated with a lower incidence of death and major adverse cardiovascular and cerebrovascular events at 10 years.

Automation of intracoronary continuous thermodilution for absolute coronary flow and microvascular resistance measurements

AIM

Microvascular resistance reserve (MRR) as derived from continuous intracoronary thermodilution specifically quantifies microvasculature function. As originally described, the technique necessitates reinstrumentation of the artery and manual reprogramming of the infusion pump when performing resting and hyperemic measurements. To simplify and to render this procedure operator-independent, we developed a fully automated method. The aim of the present study is to validate the automated procedure against the originally described one.

METHODS AND RESULTS

For the automated procedure, an infusion pump was preprogrammed to allow paired resting-hyperemic thermodilution assessment without interruption. To validate the accuracy of this new approach, 20 automated measurements were compared to those obtained in the same vessels with conventional paired resting-hyperemic thermodilution measurements (i.e., with a sensor pullback at each infusion rate and manual reprogramming of the infusion pump).  A close correlation between the conventional and the automated measuring technique was found for resting flow (Q_rest : r = 0.89, mean bias = 2.52; SD = 15.47), hyperemic flow (Q_hyper : r = 0.88, mean bias = -2.65; SD = 27.96), resting microvascular resistance (R_μ-rest : r = 0.90, mean bias = 52.14; SD = 228.29), hyperemic microvascular resistance R_μ-hyper : r = 0.92, mean bias = 12.95; SD = 57.80), and MRR (MRR: r = 0.89, mean bias = 0.04, SD = 0.59).  Procedural time was significantly shorter with the automated method (5'25″ ± 1'23″ vs. 4'36″​​​​​​​ ± 0'33″​​​​​​​, p = 0.013).

CONCLUSION

Continuous intracoronary thermodilution-derived measurements of absolute flow, absolute resistance, and MRR can be fully automated. This further shortens and simplifies the procedure when performing paired resting-hyperemic measurements.

Modelling coronary flows: impact of differently measured inflow boundary conditions on vessel-specific computational hemodynamic profiles

BACKGROUND AND OBJECTIVES

The translation of hemodynamic quantities based on wall shear stress (WSS) or intravascular helical flow into clinical biomarkers of coronary atherosclerotic disease is still hampered by the assumptions/idealizations required by the computational fluid dynamics (CFD) simulations of the coronary hemodynamics. In the resulting budget of uncertainty, inflow boundary conditions (BCs) play a primary role. Accordingly, in this study we investigated the impact of the approach adopted for in vivo coronary artery blood flow rate assessment on personalized CFD simulations where blood flow rate is used as inflow BC.

METHODS

CFD simulations were carried out on coronary angiograms by applying personalized inflow BCs derived from four different techniques assessing in vivo surrogates of flow rate: continuous thermodilution, intravascular Doppler, frame count-based 3D contrast velocity, and diameter-based scaling law. The impact of inflow BCs on coronary hemodynamics was evaluated in terms of WSS- and helicity-based quantities.

RESULTS

As main findings, we report that: (i) coronary flow rate values may differ based on the applied flow derivation technique, as continuous thermodilution provided higher flow rate values than intravascular Doppler and diameter-based scaling law (p = 0.0014 and p = 0.0023, respectively); (ii) such intrasubject differences in flow rate values lead to different surface-averaged values of WSS magnitude and helical blood flow intensity (p<0.0020); (iii) luminal surface areas exposed to low WSS and helical flow topological features showed robustness to the flow rate values.

CONCLUSIONS

Although the absence of a clinically applicable gold standard approach prevents a general recommendation for one coronary blood flow rate derivation technique, our findings indicate that the inflow BC may impact computational hemodynamic results, suggesting that a standardization would be desirable to provide comparable results among personalized CFD simulations of the coronary hemodynamics.

Prevalence of Coronary Microvascular Disease and Coronary Vasospasm in Patients With Nonobstructive Coronary Artery Disease: Systematic Review and Meta-Analysis

Background

A relevant proportion of patients with suspected coronary artery disease undergo invasive coronary angiography showing normal or nonobstructive coronary arteries. However, the prevalence of coronary microvascular disease (CMD) and coronary spasm in patients with nonobstructive coronary artery disease remains to be determined. The objective of this study was to determine the prevalence of coronary CMD and coronary vasospastic angina in patients with no obstructive coronary artery disease.

Methods and Results

A systematic review and meta‐analysis of studies assessing the prevalence of CMD and vasospastic angina in patients with no obstructive coronary artery disease was performed. Random‐effects models were used to determine the prevalence of these 2 disease entities. Fifty‐six studies comprising 14 427 patients were included. The pooled prevalence of CMD was 0.41 (95% CI, 0.36–0.47), epicardial vasospasm 0.40 (95% CI, 0.34–0.46) and microvascular spasm 24% (95% CI, 0.21–0.28). The prevalence of combined CMD and vasospastic angina was 0.23 (95% CI, 0.17–0.31). Female patients had a higher risk of presenting with CMD compared with male patients (risk ratio, 1.45 [95% CI, 1.11–1.90]). CMD prevalence was similar when assessed using noninvasive or invasive diagnostic methods.

Conclusions

In patients with no obstructive coronary artery disease, approximately half of the cases were reported to have CMD and/or coronary spasm. CMD was more prevalent among female patients. Greater awareness among physicians of ischemia with no obstructive coronary arteries is urgently needed for accurate diagnosis and patient‐tailored management.

Development, validation, and reproducibility of the pullback pressure gradient (PPG) derived from manual fractional flow reserve pullbacks

Fractional flow reserve (FFR) pullbacks assess the location and magnitude of pressure drops along the coronary artery. The pullback pressure gradient (PPG) quantifies the FFR pullback curve and provides a numeric expression of focal versus diffuse coronary artery disease. This study aims (1) to validate the PPG using manual FFR pullbacks compared with motorized FFR pullbacks as a reference; and (2) to determine the intra- and interoperator reproducibility of the PPG derived from manual FFR pullbacks. Patients with stable coronary artery disease and an FFR ≤ 0.80 were included. All patients underwent FFR pullback evaluation either with a motorized device or manually, depending on the study cohort. The agreement of the PPG between repeated pullbacks was assessed using the Bland-Altman method. Overall, 116 FFR pullback maneuvers (96 manual and 20 motorized) were analyzed. There was excellent agreement between the PPG derived from manual and motorized pullbacks (mean difference -0.01 ± 0.07, 95% limits of agreement [LOA] -0.14 to 0.12). The intra- and interoperator reproducibility of PPG derived from manual pullbacks were excellent (mean difference <0.01, 95% LOA -0.11 to 0.12, and mean difference <0.01, 95% LOA -0.12 to 0.11, respectively). The duration of the pullback maneuver did not impact the reproducibility of the PPG (r = 0.12, 95% CI: -0.29 to 0.49, p = 0.567). Manual pullbacks allow for an accurate PPG calculation. The inter- and intraoperator reproducibility of PPG derived from manual pullbacks were excellent.

Physiological and angiographic outcomes of PCI in calcified lesions after rotational atherectomy or intravascular lithotripsy

BACKGROUND

Percutaneous coronary interventions (PCI) in calcified coronary artery lesions are associated with impaired stent expansion, higher rate of periprocedural complications and cardiac mortality. Lesion preparation using calcium modifying techniques such as Rotational Atherectomy (RA) or Intravascular Lithotripsy (IVL) has been advocated. Studies comparing these technologies are lacking. We aimed to compare the in-stent pressure gradient, evaluated by virtual fractional flow-reserve, in calcific lesions treated using either RA or IVL.

METHODS

Patients undergoing either RA- or IVL-assisted PCI from two European centers were included. Propensity score matching (1:2) was performed to control for potential bias. Primary outcome was post- PCI in-stent pressure gradient calculated by virtual fractional flow reserve (vFFRgrad). Secondary outcomes included the proportion of patients with complete functional revascularization defined as of distal vFFR post PCI (vFFRpost) ≥ 0.90.

RESULTS

From a cohort of 210 patients, 105 matched patients (70 RA and 35 IVL) were included. Pre-PCI vFFR did not differ between groups (0,65 ± 0,13 RA and 0,67 ± 0,11 IVL). After PCI, in-stent pressure gradients were significantly lower in the IVL group (0.032 ± 0.026 vs 0.043 ± 0.026 in the RA group, p = 0.024). The proportions of vessels with functional complete revascularization was similar between the two groups (32.9% vs. 37.1% in the RA and IVL group, respectively; p = 0.669).

CONCLUSIONS

Calcific lesions preparation with IVL is effective and resulted in improved in-stent pressure gradient compared to RA. Approximately one third of the patients undergoing PCI for a severely calcified lesion achieved functional revascularization with no difference between rotational RA and IVL.

389 Microvascular dysfunction in patients with Type II diabetes mellitus: invasive assessment of absolute coronary blood flow and microvascular resistance reserve

Aims

Coronary microvascular dysfunction (CMD) is an early feature of diabetic cardiomyopathy, which usually precedes the onset of diastolic and systolic dysfunction. Continuous intracoronary thermodilution allows an accurate and reproducible assessment of absolute coronary blood flow and microvascular resistance thus allowing the evaluation of coronary flow reserve (CFR) and Microvascular Resistance Reserve (MRR), a novel index specific for microvascular function, which is independent from the myocardial mass. In the present study we compared absolute coronary flow and resistance, CFR and MRR assessed by continuous intracoronary thermodilution in diabetic vs. non-diabetic patients. Left atrial reservoir strain (LASr), an early marker of diastolic dysfunction was compared between the two groups.

Methods

In this observational retrospective study, 108 patients with suspected angina and non-obstructive coronary artery disease (NOCAD) consecutively undergoing elective coronary angiography (CAG) from September 2018 to June 2021 were enrolled. The invasive functional assessment of microvascular function was performed in the left anterior descending artery (LAD) with intracoronary continuous thermodilution. Patients were classified according to the presence of DM. Absolute resting and hyperaemic coronary blood flow (in mL/min) and resistance (in WU) were compared between the two cohorts. FFR was measured to assess coronary epicardial lesions, while CFR and MRR were calculated to assess microvascular function. LAS, assessed by speckle tracking echocardiography, was used to detect early myocardial structural changes potentially associated with microvascular dysfunction.

Results

The median FFR value was 0.83 (0.79–0.87) without any significant difference between the two groups. Absolute resting and hyperaemic flow in the left anterior descending coronary were similar between diabetic and non-diabetic patients. Similarly, resting and hyperaemic resistances did not change significantly between the two groups. In the DM cohort the CFR and MRR were significantly lower compared to the control group [CFR = 2.38 ± 0.61 and 2.88 ± 0.82; MRR = 2.79 ± 0.87 and 3.48 ± 1.02 for diabetic and non-diabetic patients respectively, (P &lt; 0.05 for both)]. Likewise, diabetic patients had a significantly lower reservoir, contractile and conductive LAS (all P &lt; 0.05).

Conclusions

Compared with non-diabetic patients, CFR and MRR were lower in patients with DM and non-obstructive epicardial coronary arteries, while both resting and hyperaemic coronary flow and resistance were similar. LASr was lower in diabetic patients, confirming the presence of a subclinical diastolic dysfunction associated to the microcirculatory impairment. Continuous intracoronary thermodilution-derived indexes provide a reliable and operator-independent assessment of coronary macro- and microvasculature and might potentially facilitate widespread clinical adoption of invasive physiologic assessment of suspected microvascular disease.

451 Deferral of coronary revascularization in patients with reduced ejection fraction based on physiological assessment: impact on long-term survival

Aims

Deferring percutaneous coronary intervention (PCI) in patients with non-significant stenoses based on fractional flow reserve (FFR) is associated with favourable clinical outcomes up to 15 years. Whether this holds true in patients with reduced left ventricular ejection fraction (LVEF) is unclear. To investigate whether FFR provides adjunctive clinical benefit compared to coronary angiography in deferring revascularization of patients with intermediate coronary stenoses and reduced LVEF.

Methods and results

Consecutive patients (n = 4577) with reduced LVEF (≤50%) undergoing coronary angiography between 2002 and 2010 were screened. We eventually included patients with at least one intermediate coronary stenosis (diameter stenosis ≥40%) in whom revascularization was deferred based either on angiography plus FFR (FFR-guided) or angiography alone (angiography-guided). The primary endpoint of the study was the cumulative incidence of all-cause death at 10 years. The secondary endpoint [the incidence of major adverse cardiovascular and cerebrovascular events (MACCE)], was a composite of all-cause death, myocardial infarction, any revascularization and stroke. A total of 840 patients were included (206 in the FFR-guided and 634 in the angiography-guided group). Median clinical follow-up was 7 years [IQR: (3.22–11.08)]. After 1:1 propensity score matching, baseline characteristics between the two groups were similar. All-cause death was significantly lower in the FFR-guided group compared with the angiography-guided group [94 (45.6%) vs. 119 (57.8%), HR: 0.65 (95% CI: 0.49–0.85), P &lt; 0.01]. The rate of major adverse cardiovascular and cerebrovascular events [(MACCE), a composite of all-cause death, myocardial infarction, any revascularization, and stroke) was lower in the FFR-guided group [123 (59.7%) vs. 139 (67.5%), HR: 0.75 (95% CI: 0.59–0.95), P = 0.02].

Conclusions

In patients with reduced LVEF, deferring revascularization of intermediate coronary stenoses based on FFR is associated with a lower incidence of death and MACCE at 10 years.

662 Physiological and angiographic outcomes of PCI in calcified lesions after rotational atherectomy or intravascular lithotripsy

Aims

Percutaneous coronary interventions (PCI) in calcified coronary artery lesions are associated with impaired stent expansion, higher rate of periprocedural complications and cardiac mortality. Lesion preparation using calcium modifying techniques such as Rotational Atherectomy (RA) or Intravascular Lithotripsy (IVL) has been advocated. Studies comparing these technologies are lacking. We aimed to compare the in-stent pressure gradient, evaluated by virtual fractional flow-reserve, in calcific lesions treated using either RA or IVL.

Methods and results

Patients undergoing either RA- or IVL-assisted PCI from two European centres were included. Propensity score matching (1:2) was performed to control for potential bias. Primary outcome was post-PCI in-stent pressure gradient calculated by virtual fractional flow reserve (vFFRgrad). Secondary outcomes included the proportion of patients with complete functional revascularization defined as of distal vFFR post PCI (vFFRpost) ≥0.90. From a cohort of 210 patients, 105 matched patients (70 RA and 35 IVL) were included. Pre-PCI vFFR did not differ between groups (0.65 ± 0.13 RA and 0.67 ± 0.11 IVL). After PCI, in-stent pressure gradients was significantly lower in the IVL group (0.032 ± 0.026 vs. 0.043 ± 0.026 in the RA group, P = 0.024). The proportion of vessels with functional complete revascularization was similar between the two groups (32.9% vs. 37.1% in the RA and IVL group, respectively; P = 0.669).

Conclusions

Calcific lesions preparation with IVL is effective and resulted in improved in-stent pressure gradient compared to RA. Approximately one third of the patients undergoing PCI for a severely calcified lesion achieved functional revascularization with no difference between rotational RA and IVL. 662 FigureIn stent gradients after RA and IVL. (A) Box plot depicting the distribution of the in-stent pressure gradient vFFRgrad between the two groups. (B) Cumulative frequency distribution curves demonstrating lower vFFRgrad after intravascular lithotripsy compared to rotational atherectomy. RA, rotational atherectomy; IVL, intravascular lithotripsy; vFFRgrad, in-stent pressure gradient.

452 Saline-induced coronary hyperaemia is mediated by intravascular haemolysis

Aims

Absolute coronary blood flow can be measured by intracoronary continuous thermodilution of saline through the lateral side holes of a dedicated infusion catheter placed in the proximal segment of the coronary artery. A room-temperature saline infusion rate at 15–20 ml/min induces an immediate, steady-state, maximal microvascular vasodilation. The mechanism of this hyperemic response remains unclear. The aim of the present study is to test whether local haemolysis is a potential mechanism of coronary hyperaemia.

Methods and results

Twelve patients undergoing left and right catheterization were included. The left coronary artery and the coronary sinus were selectively cannulated. Absolute resting and hyperemic coronary flow were measured using the continuous intracoronary thermodilution of saline through a dedicated infusion catheter (RayFlow®). Arterial and venous samples were collected from the coronary artery and the coronary sinus in five phases: baseline (BL); resting flow measurement (Rest, saline infusion at 10 ml/min); hyperaemia (Hyperaemia, saline infusion at 20 ml/min); post-hyperaemia [Post-Hyperaemia, 2 min after the cessation of saline infusion; and control phase (Control, during infusion of saline through the guide catheter at 30 mL/min). Haemolysis was visually detected only in the centrifugated venous blood samples collected during the Hyperaemia phase. As compared to Rest, during Hyperaemia both LDH [131.50 ± 21.89 U/dL (Rest) and 258.33 ± 57.40 U/dl (Hyperaemia), P &lt; 0.001] and plasma-free haemoglobin [PFHb, 4.92 ± 3.82 mg/dl (Rest) and 108.42 ± 46.58 mg/dl (Hyperaemia), P &lt; 0.001] significantly increased in the coronary sinus. The percentage of haemolysis was significantly higher during the hyperaemia phase [0.04 ± 0.02% (Rest) vs. 0.89 ± 0.34% (Hyperaemia), P &lt; 0.001].

Conclusions

Saline-induced hyperaemia through a dedicated intracoronary infusion catheter is associated with haemolysis. Vasodilatory compounds released locally, like ATP, are likely ultimately responsible for localized microvascular vasodilation. The role of other substances released by erythrocytes in inducing hyperaemia cannot be excluded and requires further investigations.

Risk of myocardial infarction based on endothelial shear stress analysis using coronary angiography

BACKGROUND AND AIMS

Wall shear stress (WSS) has been associated with atherogenesis and plaque progression. The present study assessed the value of WSS analysis derived from conventional coronary angiography to detect lesions culprit for future myocardial infarction (MI).

METHODS AND RESULTS

Three-dimensional quantitative coronary angiography (3DQCA), was used to calculate WSS and pressure drop in 80 patients. WSS descriptors were compared between 80 lesions culprit of future MI and 108 non-culprit lesions (controls). Endothelium-blood flow interaction was assessed by computational fluid dynamics (10.8 ± 1.41 min per vessel). Median time between baseline angiography and MI was 25.9 (21.9-29.8) months. Mean patient age was 70.3 ± 12.7. Clinical presentation was STEMI in 35% and NSTEMI in 65%. Culprit lesions showed higher percent area stenosis (%AS), translesional vFFR difference (ΔvFFR), time-averaged WSS (TAWSS) and topological shear variation index (TSVI) compared to non-culprit lesions (p < 0.05 for all). TSVI was superior to TAWSS in predicting MI (AUC-TSVI = 0.77, 95%CI 0.71-0.84 vs. AUC-TAWSS = 0.61, 95%CI 0.53-0.69, p < 0.001). The addition of TSVI increased predictive and reclassification abilities compared to a model based on %AS and ΔvFFR (NRI = 1.04, p < 0.001, IDI = 0.22, p < 0.001).

CONCLUSIONS

A 3DQCA-based WSS analysis was feasible and can identify lesions culprit for future MI. The combination of area stenoses, pressure gradients and WSS predicted the occurrence of MI. TSVI, a novel WSS descriptor, showed strong predictive capacity to detect lesions prone to cause MI.

Microvascular Dysfunction in Patients With Type II Diabetes Mellitus: Invasive Assessment of Absolute Coronary Blood Flow and Microvascular Resistance Reserve

Background: Coronary microvascular dysfunction (CMD) is an early feature of diabetic cardiomyopathy, which usually precedes the onset of diastolic and systolic dysfunction. Continuous intracoronary thermodilution allows an accurate and reproducible assessment of absolute coronary blood flow and microvascular resistance thus allowing the evaluation of coronary flow reserve (CFR) and Microvascular Resistance Reserve (MRR), a novel index specific for microvascular function, which is independent from the myocardial mass. In the present study we compared absolute coronary flow and resistance, CFR and MRR assessed by continuous intracoronary thermodilution in diabetic vs. non-diabetic patients. Left atrial reservoir strain (LASr), an early marker of diastolic dysfunction was compared between the two groups. Methods: In this observational retrospective study, 108 patients with suspected angina and non-obstructive coronary artery disease (NOCAD) consecutively undergoing elective coronary angiography (CAG) from September 2018 to June 2021 were enrolled. The invasive functional assessment of microvascular function was performed in the left anterior descending artery (LAD) with intracoronary continuous thermodilution. Patients were classified according to the presence of DM. Absolute resting and hyperemic coronary blood flow (in mL/min) and resistance (in WU) were compared between the two cohorts. FFR was measured to assess coronary epicardial lesions, while CFR and MRR were calculated to assess microvascular function. LAS, assessed by speckle tracking echocardiography, was used to detect early myocardial structural changes potentially associated with microvascular dysfunction. Results: The median FFR value was 0.83 [0.79-0.87] without any significant difference between the two groups. Absolute resting and hyperemic flow in the left anterior descending coronary were similar between diabetic and non-diabetic patients. Similarly, resting and hyperemic resistances did not change significantly between the two groups. In the DM cohort the CFR and MRR were significantly lower compared to the control group (CFR = 2.38 ± 0.61 and 2.88 ± 0.82; MRR = 2.79 ± 0.87 and 3.48 ± 1.02 for diabetic and non-diabetic patients respectively, [p < 0.05 for both]). Likewise, diabetic patients had a significantly lower reservoir, contractile and conductive LAS (all p < 0.05). Conclusions: Compared with non-diabetic patients, CFR and MRR were lower in patients with DM and non-obstructive epicardial coronary arteries, while both resting and hyperemic coronary flow and resistance were similar. LASr was lower in diabetic patients, confirming the presence of a subclinical diastolic dysfunction associated to the microcirculatory impairment. Continuous intracoronary thermodilution-derived indexes provide a reliable and operator-independent assessment of coronary macro- and microvasculature and might potentially facilitate widespread clinical adoption of invasive physiologic assessment of suspected microvascular disease.

Angiography vs physiology-based deferral of revascularization in patients with reduced left ventricular ejection fraction: a 10-year clinical follow-up

Background

Deferring percutaneous coronary intervention (PCI) in patients with non-ischemic coronary stenoses based on fractional flow reserve (FFR) and preserved left ventricular ejection fraction (LVEF) is associated with favorable long-term clinical outcomes. In patients with reduced LVEF, the role of reversible/residual ischemia in deferring revascularization is still debated.

Purpose

To investigate whether FFR provides additive clinical benefit compared to coronary angiography in deferring revascularization in patients with intermediate coronary stenoses and reduced LVEF.

Methods

Among 4577 coronary angiographies performed between 2002 and 2010, consecutive patients with reduced LVEF (≤50%) and at least one intermediate coronary stenosis [diameter stenosis (DS)% 40–70%] in whom revascularization was deferred based either on FFR (FFR-guided) or angiography (Angiography-guided) were screened. The primary endpoint of the study was cumulative incidence of death at 10 years.

Results

A total of 843 patients were included (209 in the FFR-guided and 634 in the Angio-guided group). Median clinical follow-up was 7.1 years (IQR 3.2–11.2 years). After 1:1 propensity score matching, baseline characteristics between the two groups were similar. All-cause death at 10 years was significantly lower in the FFR-guided compared with the Angiography-guided group (94 [45%] vs 115 [55%], HR 0.72 [95% CI 0.55–0.95], p&lt;0.05). Similarly, the incidence of major adverse cardiovascular and cerebrovascular events (MACCE, composite of all-cause death, myocardial infarction, any revascularization and stroke) was lower in the FFR guided group (125 [60%] vs 140 [67%], HR 0.77 [95% CI 0.61–0.98], p&lt;0.05).

Conclusions

In patients with reduced LVEF and associated coronary artery disease, deferring revascularization of intermediate stenoses based on FFR is associated with lower incidence of death and MACCE at 10 years.

Funding Acknowledgement

Type of funding sources: None.

Physiological and angiographic outcomes of PCI in calcified lesions after rotational atherectomy or intravascular lithotripsy

Background

Percutaneous coronary interventions (PCI) in calcified coronary artery lesions is associated with impaired stent expansion, higher rate of periprocedural complications and cardiac mortality. Lesion preparation using dedicated calcium modifying techniques such as RA or IVL has been advocated. Studies comparing these technologies are lacking.

Objectives

To compare the in-stent pressure gradient, evaluated by virtual fractional flow-reserve, in calcific lesions treated using either rotational atherectomy (RA) or intravascular lithotripsy (IVL).

Methods

Patients undergoing either RA- or IVL-assisted PCI from two European centers were included. Propensity score matching (1:2) was performed to control for potential bias. Primary outcome was post- PCI in-stent pressure gradient calculated by virtual fractional flow reserve (vFFRgrad, calculated as the difference between the vFFR at the proximal minus distal edge of the stent). Secondary outcomes included the proportion of patients with complete functional revascularization defined as of distal vFFR post PCI (vFFRpost) ≥0.90.

Results

From a cohort of 210 patients, 105 matched patients (70 RA and 35 IVL) were included. Pre-PCI vFFR did not differ between groups (0,65±0,13 RA and 0,67±0,11 IVL). After PCI, in-stent pressure gradient was significantly lower in the IVL group (0.032±0.026 vs 0.043±0.026 in the RA group, p=0.024). The proportion of vessels with functional complete revascularization was similar between the two groups (32.9% vs. 37.1% in the RA and IVL group, respectively; p=0.669)

Conclusions

Calcific lesions preparation with IVL is effective and resulted in improved in-stent pressure gradient compared to RA. Approximately one third of the patients undergoing PCI for a severely calcified lesion achieved functional revascularization with no difference between rotational RA and IVL.

Funding Acknowledgement

Type of funding sources: None. In stent gradients after RA and IVL

Microvascular Resistance Reserve for Assessment of Coronary Microvascular Function: JACC Technology Corner

The need for a quantitative and operator-independent assessment of coronary microvascular function is increasingly recognized. We propose the theoretical framework of microvascular resistance reserve (MRR) as an index specific for the microvasculature, independent of autoregulation and myocardial mass, and based on operator-independent measurements of absolute values of coronary flow and pressure. In its general form, MRR equals coronary flow reserve (CFR) divided by fractional flow reserve (FFR) corrected for driving pressures. In 30 arteries, pressure, temperature, and flow velocity measurements were obtained simultaneously at baseline (BL), during infusion of saline at 10 mL/min (rest) and 20 mL/min (hyperemia). A strong correlation was found between continuous thermodilution-derived MRR and Doppler MRR (r = 0.88; 95% confidence interval: 0.72-0.93; P < 0.001). MRR was independent from the epicardial resistance, the lower the FFR value, the greater the difference between MRR and CFR. Therefore, MRR is proposed as a specific, quantitative, and operator-independent metric to quantify coronary microvascular dysfunction.