Concordant low and discordant fractional flow reserve and instantaneous wave-free ratio measurements are associated with reduced myocardial perfusion

Background

In patients undergoing invasive coronary angiography with functional lesion assessment, both fractional flow reserve (FFR) and instantaneous wave-free ratio (iFR) measurements can be used to guide coronary revascularization decision-making. The hemodynamic significance of lesions with discordant FFR and iFR measurements is debated.

Purpose

This study compared quantitative myocardial perfusion indices as assessed by [15O]H2O positron emission tomography (PET) perfusion imaging in vessels with concordant high, discordant and concordant low FFR/iFR measurements

Methods

This post-hoc analysis of the PACIFIC I and II studies included 198 patients suspected of obstructive coronary artery disease who had undergone [15O]H2O PET imaging and subsequent FFR/iFR interrogation in 468 vessels. Resting myocardial blood flow (MBF), hyperemic MBF and coronary flow reserve (CFR) were compared between 4 vessel subgroups: FFR+/iFR+ (n=79), FFR−/iFR+ (n=22), FFR+/iFR− (n=22) and FFR−/iFR− (n=345).

Results

Discordant FFR/iFR indices were found in 44 (9%) vessels. Hyperemic MBF was significantly lower for vessels with FFR+/iFR+ (2.09±0.67 mL min–1 g–1), FFR−/iFR+ (2.41±0.80 mL min–1 g–1) and FFR+/iFR− (2.40±0.69 mL min–1 g–1) compared to FFR−/iFR− vessels (2.91±0.84 mL min–1 g–1) (p<0.01, p=0.03 and p<0.01, respectively). Hyperemic MBF did not differ between vessels with FFR+/iFR+ compared to FFR−/iFR+ (p=0.38) and FFR+/iFR− (p=0.35) vessels. In addition, resting MBF was lower and CFR did not differ in the FFR+/iFR− versus the FFR−/iFR− group (resting MBF: 0.80±0.16 mL min–1 g–1 vs. 0.90±0.24 mL min–1 g–1, p=0.03 and CFR: 3.05±0.84 vs. 3.35±1.07, p=0.56). Finally, CFR was similar in FFR+/iFR+ and FFR−/iFR+ vessels (2.37±0.76 vs. 2.64±0.84, p=0.92).

Conclusions

We found lower baseline flow and similar flow reserve in FFR+/iFR− compared to FFR−/iFR− vessels. Importantly, [15O]H2O PET imaging demonstrated reduced hyperemic MBF in vessels with concordant low and discordant FFR and iFR measurements.

Funding Acknowledgement

Type of funding sources: None.

The effect of chronic total coronary occlusion percutaneous coronary intervention on absolute perfusion in remote myocardium

Background

Successful revascularization of a chronic total coronary occlusion (CTO) impacts coronary physiology of the remote myocardial territory.

Purpose

This study evaluated the effect of CTO percutaneous coronary intervention (PCI) on changes in absolute perfusion in remote myocardium as assessed by serial [15O]H2O positron emission tomography (PET) perfusion imaging.

Methods

A total of 164 patients underwent [15O]H2O PET imaging at baseline and 3 months after successful single-vessel revascularization of a CTO to evaluate changes in hyperemic myocardial blood flow (hMBF) and coronary flow reserve (CFR) in the remote myocardial territory supplied by both non-target coronary arteries.

Results

Remote hMBF and CFR improved (2.29±0.67 to 2.48±0.75 mL min–1 g–1 and 2.48±0.76 to 2.74±0.85, respectively) after CTO revascularization (p<0.01 for both). Absolute perfusion indices in the CTO vessel and the remote myocardium showed a positive linear correlation, both before (r=0.75, p<0.01 and r=0.77, p<0.01 for hMBF and CFR, respectively) and after (hMBF: r=0.87, p<0.01 and CFR: r=0.81, p<0.01) CTO PCI. Absolute increases in remote myocardial perfusion were largest in patients with a higher increase in hMBF (βeta [β] 0.56; 95% CI: 0.47–0.65; p<0.01) and CFR (β 0.51 (0.42–0.60); p<0.01) in the CTO territory, independent of clinical, angiographic and procedural characteristics. Furthermore, baseline (hMBF: β −0.24 (−0.39, −0.08); p<0.01 and CFR: β −0.26 (−0.41, −0.11); p<0.01) and post-PCI perfusion (hMBF: β 0.36; (0.27, 0.46); p<0.01 and CFR: β 0.30 (0.21, 0.40); p<0.01) in the CTO vessel were independently associated with the increase in remote myocardial perfusion after CTO PCI.

Conclusions

An overall increase in remote myocardial perfusion was observed following CTO PCI. Absolute perfusion indices in the remote myocardium showed a positive linear correlation with perfusion in the CTO vessel, before and after CTO revascularization. Importantly, baseline, post-PCI and the absolute increase in perfusion in the CTO territory were independently associated with increases in remote myocardial perfusion after revascularization.

Funding Acknowledgement

Type of funding sources: None. Figure 1Figure 2

The association between invasive microvascular function and CMR-derived microvascular injury indicators and left ventricular function and infarct size at 1-month after reperfused STEMI

Background

The restoration of the coronary microcirculation in ST-segment elevation myocardial infarction (STEMI) patients remains hampered in up to 50% of the STEMI patients after successful primary percutaneous coronary intervention (PCI). The association between the coronary microvascular function and injury indicators and functional outcome remains debated.

Purpose

This study aims to investigate the relation between post-PCI invasive microvascular function and cardiovascular magnetic resonance (CMR)-derived microvascular injury indicators and left ventricular (LV) function and infarct size (IS) at 1-month after STEMI.

Methods

The study was performed in 110 STEMI patients who underwent angiography for primary PCI and at 1-month follow-up. Invasive assessment of coronary microcirculation physiology in the culprit artery was performed during both procedures and included coronary flow reserve (CFR) and the index of microcirculatory resistance (IMR). Data were available for 101 patients. A ratio of >2 for CFR and a value of <25 U for IMR were considered normal. CMR was performed during the acute phase (2 to 7 days after PCI) and at 1-month and provided assessment of LV function, IS and non-invasive information of microvascular injury in 78 patients by microvascular obstruction (MVO) and intra-myocardial hemorrhage (IMH).

Results

Over 1-month, CFR, IMR, LV function, and IS all significantly improved (p≤0.001). In univariable linear regression analysis, the post-PCI normal index CFR and IMR (both p=0.04), MVO presence, MVO size, IMH presence, IMH size (all, p<0.001) were significantly associated with LV ejection fraction at 1-month. Additionally, the post-PCI index CFR (p=0.04), MVO presence, MVO size, IMH presence, IMH size (all, p<0.001) were all associated with 1-month IS. In a multivariable linear regression analysis model including invasive and non-invasive coronary microcirculation function and injury indicators, MVO presence was identified as the only independent marker related to both 1-month LV ejection fraction and IS (both p<0.001).

Conclusion(s)

In STEMI patients, CMR-derived coronary microcirculation injury indicators reveal a closer association with 1-month LV function and IS outcome than invasive microcirculatory measurements. MVO presence is independently associated with 1-month LV ejection fraction and IS.

Funding Acknowledgement

Type of funding sources: Private company. Main funding source(s): The REDUCE-MVI study was funded by Astra Zeneca to MvL and NvR.

Residual quantitative flow ratio to estimate post-intervention fractional flow reserve

Objective

To assess the performance of residual quantitative flow ratio (QFR) to estimate post percutaneous coronary intervention (PCI) fractional flow reserve (FFR).

Background

QFR computes FFR based on invasive coronary angiography (ICA) images. Residual QFR is a novel tool that assesses the functional outcome of an intervention by estimating post-PCI FFR.

Methods

Residual QFR analyses, using pre-PCI ICA images, were attempted in 159 vessels with post-PCI FFR measurements. QFR lesion location was matched with the treated segment to allow virtual removal of the lesion similar to the performed PCI and computation of residual QFR (Picture 1: case example of residual QFR analysis). A post-PCI FFR <0.90 was used to define a suboptimal PCI result.

Results

Residual QFR computation was successful in 128 (81%) vessels. Median residual QFR was higher than post-PCI FFR (0.96 interquartile range (IQR): 0.91–0.99 vs. 0.91 IQR: 0.86–0.96, p<0.001). A moderate correlation and agreement was observed between residual QFR and post-PCI FFR (Spearman correlation coefficient=0.56 and Intraclass correlation coefficient=0.47, p<0.001 for both). Following PCI, an FFR <0.90 was observed in 54 (42%) vessels. Specificity, positive predictive value, sensitivity, and negative predictive value of residual QFR for determining a suboptimal PCI result were 96% (95% confidence interval (CI): 87–99%), 89% (95% CI: 72–96%), 44% (95% CI: 31–59%), and 70% (95% CI: 65–75%), respectively. Overall, residual QFR had an accuracy of 74% (95% CI: 66–82%) and an area under the receiver operating characteristic curve of 0.79 for assessing a post PCI FFR <0.90.

Conclusion

A moderate correlation and agreement between residual QFR and post-PCI FFR was observed. Residual QFR ≥0.90 does not necessarily commensurate with an optimal PCI result. However, residual QFR <0.90 is a good indicator of a post-PCI FFR <0.90 and might therefore be utilized to determine PCI location in order to obtain a satisfactory PCI result (Picture 2: central illustration).

Funding Acknowledgement

Type of funding sources: None. Case example of residual QFR analysisCentral illustration

Impact of coronary revascularization on regional artery-specific coronary flow capacity: a serial [15O]H2O positron emission tomography perfusion imaging study

Funding Acknowledgements

Type of funding sources: None.

Background. Coronary flow capacity (CFC) combines absolute hyperemic myocardial blood flow (hMBF) and coronary flow reserve (CFR) in a graphical representation of the severity of myocardial perfusion impairment. Studies evaluating the impact of coronary revascularization on CFC as assessed by [15O]H2O positron emission tomography (PET) are lacking.

Purpose. The present study explored the impact of coronary revascularization on regional, artery-specific CFC as assessed by [15O]H2O PET.

Methods. A total of 315 patients (mean age 62 ± 10 years) underwent absolute myocardial perfusion imaging at baseline and directly after either percutaneous or surgical coronary revascularization (at 110 ± 50 days). Revascularized perfusion regions were stratified in 3 CFC groups at baseline: severely reduced CFC (defined as myocardial ischemia), moderately reduced CFC and normal CFC.

Results. Baseline CFC was severely reduced in 262 vessels (70%), moderately reduced in 95 vessels (25%) and normal in 17 vessels (5%). Regional, artery-specific CFC, hMBF and CFR improved after successful revascularization (P < 0.01). In 127/262 regions, CFC increased from severely reduced to moderately reduced and in 29/262 to normal flow after revascularization (p < 0.01 for both). Additionally, 28/95 revascularized regions increased from moderately reduced to normal flow (P = 0.18). Changes in hMBF (severe vs. moderate vs. normal: 0.84 ± 0.73; 0.41 ± 0.60 and 0.35 ± 0.84 mL·min-1·g-1 ) and CFR (0.92 ± 0.83; 0.49 ± 1.00 and -0.39 ± 1.15) were significantly different comparing baseline CFC groups (both p < 0.01). Furthermore, mixed-model analysis including traditional CAD risk factors revealed that baseline CFC and gender were independent predictors of changes in CFC, hMBF and CFR between baseline and follow-up.

Conclusions. Successful revascularization demonstrated a significant and positive impact on regional, artery-specific CFC, hMBF and CFR. Improvements were largest among lower baseline CFC groups. Furthermore, baseline CFC was an independent predictor of change in CFC, hMBF and CFR. These results suggest that the assessment of flow capacity by [15O]H2O PET prior to revascularization may aid in the selection of regions in which absolute myocardial perfusion is most likely to improve.

Abstract Figure 1.

Pericoronary adipose tissue attenuation leads to improved prognostication beyond atherosclerotic burden and high-risk plaques in patients with suspected coronary artery disease

Funding Acknowledgements

Type of funding sources: None.

Background

Inflammation is a key component in the atherosclerotic process, initiating and sustaining plaques and serving as a trigger for plaque rupture leading to myocardial infarction. Coronary computed tomography angiography (CCTA) derived pericoronary adipose tissue attenuation (PCATa) has been proposed as surrogate marker for coronary inflammation and might improve risk assessment on top of CCTA derived cardiovascular risk-factors: atherosclerotic burden and plaque vulnerability.

Purpose

To assess the prognostic value of PCATa beyond atherosclerotic burden and high-risk plaques (HRPs).

Methods

A total of 543 patients who underwent CCTA because of suspected CAD were included. CCTA assessment comprised coronary artery calcium score (CACS), presence of obstructive CAD (≥50% stenosis) and HRPs, total plaque volume (TPV), non-calcified plaque volume (NCPV), and PCATa. The endpoint was a composite of death and non-fatal myocardial infarction (MI). Prognostic thresholds were determined for quantitative CCTA variables.

Results

During a median follow-up of 6.6 [interquartile range: 4.7-7.8] years, the endpoint was observed in 42 (20 MI/22 death) patients. CACS >83, obstructive CAD, HRPs, TPV >269mm3, and NCPV >83mm3 were associated with shorter time to the endpoint with unadujsted hazard ratio’s (HR) of 5.37 (95% confidence interval (CI): 2.56-11.29), 5.70 (95% CI: 2.40-13.55), 3.31 (95% CI: 1.80-6.07), 7.76 (95% CI: 3.59-16.81), and 6.77 (95% CI: 3.24-14.16), respectively (p < 0.001 for all). PCATa of the RCA >-74.4 Hounsfield units was associated with worse prognosis (unadjusted HR: 1.99, 95% CI: 1.04-3.79, p = 0.037), whereas PCATa of the LAD and Cx were not associated with prognosis. PCATa of the RCA remained a significant predictor of death and non-fatal MI corrected for CCTA variables and clincal chacteristics associated with the endpoint (adjusted HR: 2.11, 95% CI: 1.11-4.04, p = 0.024).

Conclusion

Coronary inflammation determined by PCATa of the RCA provides incremental prognostic value beyond clinical characteristics and comprehensive CCTA assessment.

Abstract Figure. Take-home figure

Evolution of coronary artery calcium and absolute myocardial perfusion after percutaneous revascularization: a 3-year serial hybrid [15O]H2O PET/CT imaging study

Funding Acknowledgements

Type of funding sources: None.

Background. The value of serial coronary artery calcium (CAC) scores to predict changes in absolute myocardial perfusion and epicardial vasomotor function is poorly documented.

Purpose. This study explored the association between progression of CAC score and changes in absolute myocardial perfusion.

Methods. Fifty-three patients with single-vessel coronary artery disease (CAD) underwent [15O]H2O Positron Emission Tomography/Computed Tomography at 1 month (baseline), 1 year, and 3 years after percutaneous coronary intervention (PCI) to assess CAC scores, hyperemic myocardial blood flow (hMBF), coronary flow reserve (CFR) and cold pressor test MBF (CPT-MBF), within the context of the VANISH (Impact of Vascular Reparative Therapy on Vasomotor Function and Myocardial Perfusion) trial. Relationships between baseline CAC score and evolution of perfusion indices were explored with a mixed model-analysis.

Results. Baseline CAC score was 0 in 9%, 0.1-99.9 in 40%, 100-399.9 in 36% and ≥400 in 15% of patients, respectively. In higher baseline CAC groups, scores increased more over time (overall p < 0.01). Mixed model-analysis allowed for averaging perfusion indices over all time points: hMBF (3.74 ± 0.83; 3.33 ± 0.79; 3.08 ± 0.78 and 2.44 ± 0.74 mL·min-1·g-1) and CFR (3.82 ± 1.12; 3.17 ± 0.80; 3.19 ± 0.81; 2.63 ± 0.92) were lower among higher baseline CAC  groups (p < 0.01; p = 0.03). However, no significant interaction was found between baseline CAC groups and time after PCI for all perfusion indices, denoting that evolution of perfusion indices over time were not significantly different between CAC groups. Furthermore, CAC progression was not correlated with evolution of hMBF (r = 0.08, p = 0.57), CFR (r = 0.09, p = 0.53) or CPT-MBF (r = 0.03, p = 0.82) during 3 years follow-up.

Conclusions. Higher baseline CAC was associated with lower hMBF and CFR. However, both baseline CAC and its progression were not associated with evolution of absolute hMBF, CFR and CPT-MBF over time, suggesting that CAC score and progression of CAC are poor indicators of change in absolute myocardial perfusion.

Ischemic burden reduction after chronic total occlusion percutaneous coronary intervention related to patient prognosis

Background

Chronic total occlusion (CTO) percutaneous coronary intervention (PCI) leads to major reductions in ischemic burden. However, to date, studies investigating if more ischemia reduction after CTO PCI translates into an improved patient prognosis, are lacking.

Purpose

To evaluate if change in absolute myocardial perfusion after CTO PCI is related to patient prognosis.

Methods

Between 2013–2019, 219 prospectively recruited patients with a CTO underwent quantitative [15O]H2O positron emission tomography perfusion imaging before and 3 months after successful CTO PCI in a single high-volume CTO PCI center (175 procedures/year). Changes in perfusion defect size (in myocardial segments) and hyperemic myocardial blood flow (MBF, in mL min–1 g–1) within the CTO territory after PCI were related to the combined endpoint of death or myocardial infarction (MI). Kaplan-Meier curves (log-rank test) and multivariable Cox regression (including covariates age, gender, prior MI, and left ventricular function) were used to analyze unadjusted and risk-adjusted event-free survivals with HR [95% CI].

Results

Out of 213 (97%) patients with a median follow-up of 3.2 [2.1–4.7] years, 22 (10%) patients experienced the composite of death (19, 9%) or MI (5, 2%). Event-free survival was significantly improved in patients with a perfusion defect size reduction of ≥3 segments (N=132, 62%) after CTO PCI compared to <3 segments (p=0.01, risk-adjusted: p=0.02 with HR 0.36 [0.15–0.87]), as well in patients with increase in hyperemic MBF above the median of the population (delta >1.13 mL min–1 g–1) as compared to below the median (p<0.01, risk-adjusted: p=0.01 with HR 0.27 [0.10–0.75]). After PCI, patients with ≥1 segment residual perfusion defect size in the CTO territory at follow-up (N=114, 54%) had a significantly worse event-free survival compared to patients with no residual defect size (p<0.01, risk-adjusted: p=0.01 with HR 4.12 [1.35–12.59]), whereas patients with a residual hyperemic MBF >2.30 mL min–1 g–1 (N=105, 49%) showed a better event-free survival compared to patients with lower residual hyperemic MBF levels (p=0.02, risk-adjusted: p=0.04 with HR 0.33 [0.12–0.95]).

Conclusions

Patients with more ischemic burden reduction and less residual ischemia following CTO PCI showed a major improved survival free of death or MI. A limitation was the low absolute number of events that prohibited more extensive risk-adjustment of the analyses.

Funding Acknowledgement

Type of funding source: None

Infarct characteristics and outcome of patients with transient ST-segment elevation myocardial infarction compared to ST-segment and non-ST-segment elevation myocardial infarction

Background

Up to one out of four patients with signs of ST-segment elevation myocardial infarction (STEMI) express complete normalization of ST elevation before primary revascularization procedure. This condition is commonly referred to as “transient ST-segment elevation myocardial infarction” (TSTEMI) and recent data suggests that this group of patients may have favorable outcome compared to STEMI patients. However, it is currently unknown how these patients compare to both STEMI and non-ST-segment elevation myocardial infarction (NSTEMI) patients with respect to infarct size characteristics and outcome.

Objective

This study aims to explore cardiac magnetic resonance (CMR) derived scar tissue and 1-year outcome in patients with TSTEMI by comparison to STEMI and NSTEMI.

Methods

Patients with STEMI were enrolled from two prospective studies (n=170); the patients with TSTEMI were recruited from the TRANSIENT trial (n=141); the patients with NSTEMI were prospectively and consecutively collected from local registries of Amsterdam UMC (n=57) and Maastricht UMC (n=51). All patients underwent CMR examination 2–8 days after the index event. Cine imaging was done for volume and function assessment. Late gadolinium enhancement imaging was performed to identify infarct size (in grams) and the presence of microvascular obstruction (MVO). All CMR images were processed in a single core laboratory (Amsterdam UMC). Clinical outcome after 1 year was measured by the incidence of major adverse cardiac events (MACE), defined as recurrent myocardial infarction (MI), revascularization and all cause death.

Results

The TSTEMI group demonstrated the lowest end-systolic left ventricular volume and highest left ventricular ejection fraction across the groups (overall p<0.001). Although there was a remarkably lower infarct size in TSTEMI patients compared to STEMI (1.41g [0.00–3.91] vs 13.48g [5.31–26.81], p<0.001), there was only a trend towards lower infarct size compared to NSTEMI patients (1.41g [0.00–3.91] vs 2.13g [0.00–8.64], p=0.06). Whilst MVO was observed less frequently in TSTEMI compared to STEMI patients (5 (4%) vs 53 (31%), p<0.001), no significant difference was seen between TSTEMI and NSTEMI patients (5 (4%) vs 5 (5%), p=0.72). Multivariable linear regression analysis identified infarct type, smoking, peak troponin-T and pre-PCI TIMI flow as predictors for infarct size (p=0.03, p=0.03, p<0.001 and p<0.001, respectively). One-year mortality rate was low in all 3 MI types (TSTEMI 3 (2.2%), NSTEMI 3 (3.1%), 4 (2.4%), log-rank test p=0.91). However, there was a significant difference in MACE at 1 year across the 3 MI types (TSTEMI 18 (13.2%), NSTEMI 19 (19.4%), STEMI 11 (6.7%), overall p<0.01).

Conclusion

In comparison to NSTEMI and STEMI, TSTEMI yielded favorable cardiac left ventricular function and scar mass. However, this did not lead to benefit in short term (1-year) outcome; further studies are needed with longer follow-up.

Funding Acknowledgement

Type of funding source: Other. Main funding source(s): European Association of Cardiovascular Imaging (EACVI) Research Grant

Viability and functional recovery after chronic total occlusion percutaneous coronary intervention

Background

Current guidelines advocate viability assessment to guide percutaneous coronary intervention (PCI) of chronic coronary total occlusions (CTO).

Purpose

Aim of the present study was to evaluate viability as well as global and regional functional recovery after successful CTO PCI using quantitative cardiac magnetic resonance (CMR) imaging.

Methods

132 patients with sequential CMR at baseline and 3-months after successful CTO PCI were prospectively recruited between 2013 and 2018. Segmental wall thickening (SWT) and percentage late gadolinium enhancement (LGE) were quantitatively measured per segment. Viability was defined as dysfunctional myocardium (<2.84mm SWT) with no or limited scar (≤50% LGE).

Results

Significant improvements in left ventricular (LV) ejection fraction (from 48.1±11.8 to 49.5±12.1%, p<0.01), LV end-diastolic volume (from 99.1±31.8 to 95.7±30.2ml, p<0.01), and LV end-systolic volume (from 54.4±30.5 to 51.2±29.3ml, p<0.01) were observed after CTO PCI. CTO segments with viability (N=216, (31%)) demonstrated a significantly higher increase in SWT (0.80±1.39mm) compared to CTO segments with pre-procedural preserved function (N=456 (65%), 0.07±1.43mm, p<0.01) or extensive scar (LGE >50%, N=26 (4%), −0.08±1.09mm, p<0.01). Improvement in SWT was comparable between segments with viability if further stratified to 0, >0–25, and >25–50% hyperenhancement (p=0.94). Patients with ≥2 CTO segments viability showed more SWT increase in the CTO territory compared to patients with 0–1 segment viability (0.49±0.93 vs. 0.12±0.98mm, p=0.03).

Conclusions

Improvements in LV function and volumes were significant but modest following CTO PCI. Detection of dysfunctional myocardial segments without extensive scar (≤50% LGE) as a marker for viability may aid in identifying subjects with significant regional functional recovery after CTO PCI.

Funding Acknowledgement

Type of funding source: None

No superiority of ticagrelor over prasugrel in remote myocardial inflammation in patients with acute myocardial infarction with ST elevation: a CMR T1 and T2 mapping study

Background

A number of studies suggest that acute myocardial ischaemia triggers a non-specific systemic inflammatory response of remote myocardium through the increase of plasma concentrations of acute-phase proteins, which causes myocardial oedema. As ticagrelor has been shown to significantly decrease the circulating levels of several pro-inflammatory cytokines in patients after acute myocardial infarction with ST elevation (STEMI), we sought to investigate a potential suppressive effect of ticagrelor over prasugrel on cardiac magnetic resonance (CMR) T1 and T2 values in remote myocardium.

Methods

Ninety patients presenting with acute STEMI were prospectively included and randomised to receive either ticagrelor or prasugrel maintenance treatment after successful primary percutaneous coronary intervention (PPCI). The patients underwent CMR 2–7 days after the PPCI. Studies were done on a 1.5 T clinical scanner, the protocol included long and short axis cine imaging, T1 mapping through the infarct core using a single breath-hold Shortened Modified Look-Locker Inversion Recovery (ShMOLLI), T2 mapping and late gadolinium enhancement imaging.

Results

After excluding 30 patients due to either missing images or insufficient quality of T1 or T2 maps, 60 patients were included in our analysis. Of those, 29 patients have been randomised to the ticagrelor arm and 31 patients to the prasugrel arm of the study. The mean age at inclusion was 61±10 years, 81.7% of included patients were men, the distribution was even between the two groups. There were no statistically significant differences between groups regarding past medical history and medication prior to the inclusion in the study.

CMR scans were performed 5.03±1.96 days after successful PPCI in the ticagrelor group, and 5.10±0.87 days in the prasugrel group.

Remote myocardium T1: The mean T1 value of the remote myocardium was 937±27 ms in the ticagrelor group and 936±23 ms in the prasugrel group, showing no statistical difference (p=0.85) between the groups receiving different P2Y12 inhibitor after PPCI.

Remote myocardium T2: The mean T2 value of the remote myocardium was 53.8±4.6 ms in the ticagrelor group and 53.6±4.7 ms in the prasugrel group, showing no statistical difference (p=0.86) between compared groups.

Both T1 and T2 values of the remote myocardium were above normal values published in literature.

Conclusion

In patients with STEMI after PPCI, ticagrelor maintenance therapy did not show superiority to prasugrel in preventing early remote myocardial inflammation as assessed by T1 and T2 mapping.

Additionally, findings support the premise of remote myocardial oedema following STEMI.

Funding Acknowledgement

Type of funding source: Other. Main funding source(s): Presented abstract is from a sub-study of the REDUCE-MVI study, which was conducted with financial support from Astra Zeneca through an unrestricted research grant. In addition, the study was financed by the Ministry of Economic Affairs of the Netherlands by means of a PPP Allowance made available by the Top Sector Life Sciences & Health to stimulate public-private partnerships. The first author was awarded the ESC training grant in 2019; this research was conducted during the training for which the grant was awarded.

Incremental prognostic value of pericoronary adipose tissue attenuation on top of comprehensive CCTA assessment

Background

Coronary computed tomography angiography (CCTA) derived parameters linked to severity and extent of atherosclerosis are associated with prognosis in patients with coronary artery disease (CAD). Furthermore, coronary inflammation, by determining pericoronary adipose tissue CT-attenuation (PCATa), can be assessed on CCTA as well and has been proposed as promising prognostic marker.

Objective

To assess the prognostic value of PCATa on top of traditional CCTA derived atherosclerotic parameters.

Methods

A total of 543 patients who underwent CCTA because of suspected CAD and in whom follow-up was obtained were included. CCTA assessment comprised; coronary artery calcium score (CACS), presence of obstructive CAD (≥50% stenosis) and high-risk plaques (HRP), total plaque volume (TPV), non-calcified plaque volume (NCPV), and PCATa. The endpoint was a composite of death and non-fatal myocardial infarction (MI). Optimal prognostic thresholds were determined for quantitative CCTA variables. Univariable Cox regression analyses were performed to determine clinical characteristics and CCTA variables associated with the endpoint, a subsequent multivariable Cox regression analysis that included variables associated with the endpoint was used to determine independent predictors of the endpoint. An additional Cox regression analysis was performed to test the incremental prognostic value of CCTA variables over clinical characteristics, significance of each sequentially added variable was tested using the likelihood ratio test.

Results

During a median follow-up time of 6.6 [interquartile range: 4.7–7.8] years, a total of 42 (20 MI/22 death) (8%) patients suffered an endpoint. CACS >83.2, obstructive CAD, HRP, TPV >269mm3, and NCPV >83mm3 were all associated with occurrence of the endpoint with unadujsted hazard ratio's (HR) of; 5.37, 5.70, 3.31, 7.76, and 6.77, respectively (p<0.001 for all). PCATa of the RCA above −74.4 Hounsfield units (HU) had a detrimental effect on prognosis (unadjusted HR: 1.99, p=0.037), while PCATa of the LAD nor Cx was associated with outcome (Log-rank p-value 0.255 and 0.218, respectively). PCATa of the RCA remained an independent predictor of death and MI when incorporated in a multivariable analysis inlcuding all CCTA variables and clincal chacteristics associated with the endpoint (adjusted HR: 2.11, p=0.024). Furthermore, adding PCATa of the RCA to a model that included clinical characteristics and all CCTA parameters led to an improvement of the prognostic value of the model (change in Chi-square = 4.45, p=0.035) (figure).

Conclusion

Coronary inflammation of the RCA determined by PCATa provides incremental prognostic value on top of traditional CCTA parameters linked to extent and severity of CAD.

Figure 1. Cox regression analysis demonstrating the incremental prognostic value of sequentially added CCTA variables over clinical characteristics tested for significance using the likelihood ratio test.

Funding Acknowledgement

Type of funding source: None

Defining the prognostic value of [15O]H2O positron emission tomography derived myocardial ischemic burden

Background

A myocardial ischemic burden (IB) of 10% is used to denote high-risk patients with coronary artery disease (CAD). This threshold has primarily been assessed by single-photon emission computed tomography. Differences in the pharmacokinetics of the utilized traces, higher resolution of positron emission tomography (PET), and lastly differences in assessment of IB might lead to a higher prognostic threshold for quantitative PET.

Purpose

To determine a [15O]H2O PET derived IB to identify low (annualized event rate (AER) <1.0%) and high (AER ≥3%) risk CAD patients.

Methods

623 patients who underwent [15O]H2O PET because of suspected CAD and in whom follow-up was obtained were included. The IB was defined as the percentage of myocardium with a hyperemic blood flow (hMBF) ≤2.3 ml/min/g and by a coronary flow reserve (CFR) of ≤2.5. The endpoint was a composite of death and non-fatal myocardial infarction (MI). Time-dependent ROC curves were constructed for the prediction of the endpoint within the first 5-years, based on these curves thresholds were selected for which specificity was maximized and sensitivity was at least 80%. Patients were classified as having a high IB if their respective IBs were above the prognostic thresholds and as having a low IB if not.

Results

During a median follow-up of 6.7 years, 34 (6%) patients died and 28 (4%) experienced a MI resulting in 62 (10%) endpoints. An IB of 24% and 28% for hMBF and CFR, respectively, was found to be the optimal threshold to define prognosis. Patients with a high hMBF or high CFR IB had worse outcome compared to patients with a low IB (log-rank p<0.001 for both), with AERs of 0.6% vs. 2.8%, and 0.6% vs. 2.4% (p<0.001 for both), respectively. Patients with a concordantly high hMBF and CFR derived IB had the worst outcome (AER: 3.1%), whereas patients with a concordantly low or discordant IB result had a similarly low event rate of 0.5% and 0.9% (p=0.953), respectively (log-rank p=0.445). A concordantly high hMBF and CFR IB was an independent predictor of adverse outcome beyond clinical characteristics (adjusted hazard ratio: 3.52, p<0.001).

Conclusion

An IB of 24% and 28% for hMBF and CFR was found to be the optimal prognostic threshold. Both measurements can be used to determine patients outcome. However combining hMBF and CFR IB results leads to a further refinement of risk-stratification allowing for the identification of low (concordant low or discordant IB result) and high (concordant high IB result) risk CAD patients.

Funding Acknowledgement

Type of funding source: None

Coronary computed tomography angiography and [15O]H2O positron emission tomography perfusion imaging for the assessment of coronary artery disease

Determining the anatomic severity and extent of coronary artery disease (CAD) by means of coronary computed tomography angiography (CCTA) and its effect on perfusion using myocardial perfusion imaging (MPI) form the pillars of the non-invasive imaging assessment of CAD. This review will 1) focus on CCTA and [¹⁵O]H₂O positron emission tomography MPI as stand-alone imaging modalities and their combined use for detecting CAD, 2) highlight some of the lessons learned from the PACIFIC trial (Comparison of Coronary CT Angiography, SPECT, PET, and Hybrid Imaging for Diagnosis of Ischemic Heart Disease Determined by Fractional Flow Reserve (FFR) (NCT01521468)), and 3) discuss the use of [¹⁵O]H₂O PET MPI in the clinical work-up of patients with a chronic coronary total occlusion (CTO).

Data on the impact of scan quality on the diagnostic performance of CCTA, SPECT, and PET for diagnosing myocardial ischemia defined by fractional flow reserve on a per vessel level

Scan quality directly impacts the diagnostic performance of non-invasive imaging modalities as reported in a substudy of the PACIFC-trial: “Impact of Scan Quality on the Diagnostic Performance of CCTA, SPECT, and PET for Diagnosing Myocardial Ischemia Defined by Fractional Flow Reserve” [1]. This Data-in-Brief paper supplements the hereinabove mentioned article by presenting the diagnostic performance of CCTA, SPECT, and PET on a per vessel level for the detection of hemodynamic significant coronary artery disease (CAD) when stratified according to scan quality and vascular territory.

1268A comparison between the diagnostic performance of quantitative flow ratio and non-invasive imaging modalities for diagnosing myocardial ischemia defined by FFR, a PACIFIC-trial interim analysis

Background

Quantitative flow ratio (QFR) uses fast computational algorithms based on 3-dimensional quantitative coronary angiography and estimation of contrast flow velocity during invasive coronary angiography (ICA) to obtain QFR values equivalent to fractional flow reserve (FFR).

Objective

To compare the diagnostic performance of QFR with coronary computed tomography angiography (CCTA), single-photon emission tomography (SPECT), and positron emission tomography (PET) for diagnosing myocardial ischemia defined by FFR.

Method

QFR computation was attempted in 109 patients (286 vessels without a subtotal/total lesion) of the 208 patients included in the PACIFIC-trial. Patients underwent 256-slice CCTA, Tetrofosmin SPECT, and [15O]H2O PET prior to ICA in conjunction with 3 vessel FFR measurements. ICA images were obtained without the use of a dedicated QFR acquistion protocol. QFR was calculated using a fixed empiric hyperemic flow velocity (fQFR) as well as using a patient specific flow velocity based on contrast passage through the coronary (cQFR). All analysis were performed on a per vessel level.

Results

Fixed QFR computation succeeded in 152 (53%) vessels while cQFR analysis was successful in 140 (49%) vessels. A good correlation between FFR and fQFR/cQFR was observed (R=0.774, p<0.001/R=0.790, p<0.001). The diagnostic performance in terms of sensitivity, specificity, negative predictive value, positive predictive value, and accuracy is presented in table 1. In total, 133 vessels with matched FFR, fQFR, cQFR, CCTA, SPECT, and PET results were available for the comparative C-statistic analysis, figure 1. The diagnostic performance of fQFR and cQFR was comparable (p=0.451) and superior to CCTA (p=0.004/p=0.003), SPECT (p<0.001/p<0.001), and PET (p=0.008/p=0.006), figure 1. CCTA, and PET performed alike (p=0.568) and outperformed SPECT (p=0.023, p=0.002).

Table 1 % (95% Confidence Interval) fQFR n=152 cQFR (n=140) CCTA (n=152) SPECT (n=150) PET (n=149) Sensitivity 76 (59–89) 71 (53–86) 70 (51–84) 30 (16–49) 76 (58–89) Specificity 94 (88–98) 93 (86–97) 73 (64–81) 96 (90–99) 80 (72–87) Negative Predictive Value 93 (88–96) 92 (86–95) 90 (84–94) 83 (79–86) 92 (86–96) Positive Predictive Value 79 (64–89) 74 (59–85) 42 (33–51) 67 (42–84) 52 (42–62) Accuracy 90 (84–94) 88 (81–93) 72 (65–79) 81 (74–87) 79 (72–85)

Figure 1.

Conclusion

Fixed QFR and cQFR correlate well with FFR with a high diagnostic accuracy as result. QFR outperformed CCTA, SPECT, and PET for the diagnosis of myocardial ischemia on a per vessel basis with the important footnote that fQFR and cQFR could only be computed in 53%, and 49% of the vessels.

P6181The association of coronary lumen volume to left ventricle mass ratio with myocardial blood flow and fractional flow reserve

Background

A low coronary lumen volume to left ventricle mass ratio (V/M) derived from coronary computed tomography angiography (CCTA) has been proposed as a factor contributing to impaired myocardial blood flow (MBF) even in the absence of obstructive coronary artery disease (CAD).

Objective

To elucidate the association of V/M with non-invasively obtained MBF parameters by means of [15O]H2O positron emission tomography (PET), as well as its correlations with invasively measured fractional flow reserve (FFR), overall and specifically in vessel with non-obstructive CAD.

Methods

This is a substudy of the PACIFIC trial, in which 208 patients underwent CCTA, and [15O]H2O PET prior to invasive coronary angiography (ICA) in conjunction with 3 vessel FFR measurements. Patient specific V/M was calculated for 152 patients. Matched vessel specific hyperemic MBF (hMBF), coronary flow reserve (CFR), FFR, and patient specific V/M were available for 431 vessels. The median V/M (20.71 mm3/g) was used to divide the study population into a group with a low V/M (<20.71 mm3/g) and a high V/M (≥20.71 mm3/g). Non-obstructive CAD was defined as a ≤50% stenosis grade on ICA.

Results

Overall, a higher percentage of vessels with an abnormal hMBF (34% vs. 19%, p=0.009), lower FFR values (0.93 [interquartile range: 0.85–0.97] vs. 0.95 [0.89–0.98], p=0.016), and a higher number of positive FFR values (20% vs. 9%, p=0.004) were observed among vessels in the low V/M group. Furthermore, a weak correlation between V/M, global hMBF (R=0.179, p=0.027), and global CFR (R=0.163, p=0.045) as well as a weak significant association with vessel specific hMBF (p=0.027), and FFR (p<0.001) was observed (figure 1). V/M was not independently predictive of vessels specific MBF parameters or FFR. Among vessels with non-obstructive CAD (361 vessels), an abnormal hMBF tended to be more frequently observed in vessels with a low patient specific V/M (21% vs. 13%, p=0.056). Globally, there was no correlation between V/M and hMBF nor CFR. Patient specific V/M tended to be weakly associated with vessel specific hMBF (p=0.083) and was associated with FFR (p=0.027) (figure 1). Lastly, patient specific V/M tended to be independently predictive of FFR in this specific group.

Conclusion

Overall, vessels with an abnormal hMBF, and positive FFR measurements were more frequently observed in patients with a low V/M compared to those with a high V/M. Furthermore, V/M weakly correlated with global hMBF as well as with CFR and was associated with vessel specific hMBF and FFR. However, there was no correlation between V/M and global nor vessel specific blood flow parameters in the absence of obstructive CAD, notwithstanding a weak association of V/M with FFR within this group was noted.

P3126Immediate versus delayed revascularization in patients with transient ST-elevation myocardial infarction: 1-year follow-up of the randomized clinical TRANSIENT trial

Background

Up to 24% of acute coronary syndrome patients present with ST-elevation but show complete resolution of ST-elevation and symptoms before revascularization. The current guidelines do not clearly state whether these transient ST-elevation myocardial infarction (TSTEMI) patients should be treated with a ST-elevation myocardial infarction (STEMI)-like or a non-STEMI-like invasive approach.

Purpose

The aim of the present study is to determine the effect of an immediate versus a delayed invasive strategy on infarct size measured by 4-month cardiac magnetic resonance imaging (CMR) and clinical outcome up to one year.

Methods

In this multicenter trial, 142 TSTEMI patients were randomized 1:1 to either an immediate or a delayed intervention. CMR was performed at four days and at 4-month follow-up to assess infarct size and myocardial function. Clinical follow-up was performed at four months and one year.

Results

Both in the immediate (0.4 h) and the delayed invasive group (22.7 h) CMR-derived infarct size at four months was very small and left ventricular function was good. In addition, major adverse cardiac events and all-cause mortality at one year were low and not different between both groups (table 1).

CMR and clinical outcomes up to one year Outcome Immediate invasive group (n=70) Delayed invasive group (n=72) p-value Myocardial infarct size (% of LV), median (IQR) 0.4 (0.0–3.5) 0.4 (0.0–2.5) 0.79 LVEF (%), mean ± SD 59.9±5.4 59.3±6.5 0.63 LVEF recovery (%), mean ± SD 2.2±5.4 1.7±5.3 0.66 MVO present, No. (%) 0 (0.0) 1 (1.9) 0.50 MACE (death, reinfarction, target lesion revascularization), No. (%) 3 (4.4) 4 (5.7) 1.00 Death from any cause, No. (%) 0 (0.0) 3 (4.3) 0.24 Reinfarction, No. (%) 2 (3.0) 1 (1.4) 0.62 Target lesion revascularization, No. (%) 2 (3.0) 1 (1.4) 0.62 Definite stent thrombosis, No. (%) 1 (1.5) 1 (1.4) 1.00 Abbreviations: IQR, interquartile range; LV, left ventricle; LVEF, left ventricle ejection fraction; MACE, major adverse cardiac events; MVO, microvascular obstruction; NA, not applicable; SD, standard deviation.

Conclusions

We demonstrated that patients with TSTEMI have limited infarct size and preserved left ventricular function and that an immediate or delayed approach has no effect on clinical outcome up to one year. Therefore, patients with TSTEMI can be treated with both an immediate or a delayed invasive strategy with similar outcome. These findings extend our current knowledge about the optimal timing of coronary intervention in patients with TSTEMI and complement the guidelines.

Acknowledgement/Funding

AstraZeneca, Biotronik

5962Incremental prognostic value of hybrid PET-CT assessed myocardial blood flow, coronary stenosis severity and adverse plaque characteristics

Background

Management of patients with suspected coronary artery disease (CAD) can be optimized with prognostic information derived from non-invasive imaging such as positron emission tomography (PET) perfusion imaging and coronary computed tomography angiography (CCTA). The aim of the present study was to determine the incremental prognostic value of combined functional testing using PET perfusion imaging and anatomical testing using CCTA-derived stenosis severity and morphological assessment of CCTA-derived plaque morphology.

Methods

In this retrospective study, 539 patients referred for hybrid [15O]H2O PET – CCTA imaging because of suspected CAD were investigated. PET perfusion imaging was used to determine hyperemic myocardial blood flow (MBF), whereas CCTA images were evaluated for obstructive stenosis and high-risk plaque morphology. Major adverse coronary events (MACE) included all-cause death, non-fatal myocardial infarction (MI), urgent revascularization and late non-urgent revascularization (i.e. not guided by initial diagnostic work-up with non-invasive imaging). Kaplan Meier analysis and Cox proportional hazard regression were used to evaluate the independent prognostic value of PET-derived MBF, CCTA-derived stenosis and CCTA-derived high-risk plaque.

Results

During a mean follow-up of 6.8 [4.8–7.9] years, 79 (14.7%) patients experienced MACE, including 23 (4.3%) deaths, 19 (3.5%) MIs, 8 (1.5%) urgent revascularizations and 29 (5.4%) late non-urgent revascularizations. Annualized event rates for normal vs. abnormal results of PET perfusion imaging, CCTA-derived stenosis and high-risk plaque morphology were 1.2% vs 4.1%, 0.6% vs 4.4%, and 1.7% vs 5.6%, respectively (p<0.001 for all). The combined use of these three imaging parameters resulted in excellent long-term risk prediction, with a MACE-free survival of 97% in patients with no positive imaging findings. In contrast, MACE-free survival was only 69% in patients in whom all imaging findings were positive (figure 1). Multivariate Cox proportional hazard regression demonstrated incremental prognostic value of PET perfusion imaging, CCTA-derived stenosis and CCTA-derived high-risk plaques for the occurrence of MACE (p<0.05 for all)

MACE-free survival stratified by PET-CT

Conclusion

PET-derived myocardial blood flow and CCTA-derived stenosis severity and high-risk plaque morphology are independent long-term predictors of adverse cardiac events and provide incremental prognostic value. Combined functional, anatomical and morphological assessment may allow for improved risk stratification in patients with suspected CAD.

P964Relationships between extent of ischemic burden and changes in absolute myocardial perfusion after chronic total occlusion percutaneous coronary intervention

Background

The patient benefits after chronic coronary total occlusion (CTO) percutaneous coronary intervention (PCI) are being questioned.

Purpose

The present study explored the relationships between baseline ischemic burden findings and subsequent changes in absolute myocardial perfusion after CTO PCI.

Methods

Consecutive patients underwent serial [15O]H2O positron emission tomography perfusion imaging prior and 3 months after successful CTO PCI. Change in perfusion defect size (in myocardial segments), quantitative (hyperemic) myocardial blood flow (MBF) and coronary flow reserve (CFR) in the CTO area were compared between patients with a limited (0–1 segment), moderate (2–3 segments) and large perfusion defect (≥4 segments).

Results

193 patients were included, with 15, 61 and 117 patients having a limited, moderate and large perfusion defect at baseline. Hyperemic MBF and CFR were lower in a large perfusion defect compared to smaller defects (all comparisons p&lt;0.01). The median decrease in defect size was 1 [0–1] vs 2 [1–3] vs 4 [2–5] in patients with a limited, moderate and large defect (all comparisons p&lt;0.01), whereas hyperemic MBF and CFR improved significantly regardless of baseline defect size (between groups p=0.45 and p=0.55, respectively). Furthermore, when all 193 patients were divided in a low, median and high tertile based on hyperemic MBF and CFR at baseline, changes in hyperemic MBF and CFR after CTO PCI were comparable between patients in different tertiles (between groups p=0.75 and p=0.79, respectively)

Conclusions

Patients with a CTO and a larger perfusion defect have more severe hyperemic MBF and CFR levels. Major reductions in ischemic burden can be achieved by CTO PCI, with more defect size reduction in patients with a larger perfusion defect, whereas hyperemic MBF and CFR significantly improve irrespective of starting values before PCI.

Acknowledgement/Funding

None

P5748Impact of specific crossing techniques in chronic total occlusion percutaneous coronary intervention on recovery of absolute myocardial perfusion

Background

Multiple techniques in chronic coronary total occlusion (CTO) percutaneous coronary intervention (PCI) have been developed to cross CTOs.

Purpose

To compare recovery of quantitative myocardial blood flow (MBF) after different CTO PCI techniques.

Methods

Consecutive patients with [15O]H2O positron emission tomography perfusion imaging before and three months after successful CTO PCI were included. Change in quantitative hyperemic MBF, coronary flow reserve (CFR) and perfusion defect size were compared between antegrade wire escalation (AWE), retrograde wire escalation (RWE), antegrade dissection and reentry (ADR) and retrograde dissection and reentry (RDR), and further between specific subintimal crossing and reentry techniques.

Results

193 patients were treated with AWE (N=90), RWE (N=24), ADR (N=35) and RDR (N=44). Significant improvements (all p<0.01) in hyperemic MBF (1.19±0.77, 0.94±0.65, 1.09±0.63, and 1.02±0.75 mL min–1 g–1, respectively), CFR (1.34±1.08, 1.14±1.09, 1.31±0.96, and 1.24±0.99, respectively), and perfusion defect size (3.17±2.13, 3.00±2.21, 2.74±2.09, and 2.93±1.92 segments, respectively) were comparable between the four approaches (p=0.40, p=0.84, and p=0.77, respectively). Recovery of hyperemic MBF was less pronounced after subintimal crossing with a knuckle-wire-technique compared to the use of CrossBoss in controlled ADR and RDR (p=0.02), and less after reentry with subintimal tracking and reentry (STAR) in ADR compared with controlled ADR (Stingray) or limited antegrade subintimal tracking (LAST) (p=0.02 and p<0.01).

Conclusions

Recovery of hyperemic MBF, CFR, and perfusion defect size was significant after CTO PCI and comparable between different crossing techniques. Improvement of hyperemic MBF was inferior after using the knuckle-wire subintimal crossing technique and STAR compared to other subintimal crossing and reentry techniques.

Acknowledgement/Funding

None

P5286Cardiac magnetic resonance for quantification of absolute myocardial blood flow: comparison with [15O]H2O positron emission tomography

Background

Quantification of absolute myocardial perfusion using positron emission tomography (PET) augments diagnostic performance and aids risk stratification in patients with coronary artery disease (CAD). Similar to PET, cardiac magnetic resonance imaging (CMR) allows for quantification of absolute myocardial blood flow (MBF). To date, quantitative CMR perfusion has not been compared with [15O]H2O PET, which is considered to be the gold standard for quantification of MBF.

Purpose

The purpose of this study was to compare CMR measurements of absolute myocardial perfusion to those obtained using [15O]H2O PET.

Methods

Fifty-one patients with stable CAD underwent [15O]H2O PET followed by CMR within 7 days. Late gadolinium enhancement was used to rule out presence of scar tissue. CMR perfusion imaging was performed using a single bolus dual sequence technique. Myocardial perfusion was quantified for the three main vascular territories at rest and during vasodilator stress.

Results

Pooled CMR estimates of absolute MBF correlated well with PET (r=0.79; p<0.001) and showed good agreement (intraclass correlation coefficient [ICC]=0.78; p<0.001). However, rest and stress MBF correlated weakly (r=0.31; p<0.001 for rest MBF and r=0.35; p<0.001 for stress MBF, figure) and showed poor agreement between PET and CMR (ICC=0.24; p<0.001 for rest MBF and ICC=0.34; p<0.001 for stress MBF). Similarly, CMR derived coronary flow reserve (CFR) correlated weakly (r=0.28; p<0.001) and showed poor agreement with PET derived CFR (ICC=0.23; p<0.001). Nevertheless, for a cut-off value of 2.3 mL/min/g for stress MBF and 2.5 for CFR, CMR and PET were concordant in 116 (79%) vascular territories for stress MBF and 104 (75%) vascular territories for CFR.

Per vessel – CMR vs PET perfusion

Conclusions

Resting MBF, stress MBF and CFR measurements correlated poorly with [15O]H2O PET. Nevertheless, stress MBF and CFR were concordant between CMR and [15O]H2O PET in 79% and 75% of vascular territories, respectively.

Acknowledgement/Funding

None

P6002Impaired peripheral endothelial function is associated with microvascular injury assessed by cardiac magnetic resonance imaging and decreased coronary flow in patients with STEMI

Background

Microvascular injury (MVI) occurs in about 50% of successfully revascularized ST-elevation myocardial infarction (STEMI) patients and is associated with a decreased clinical outcome. MVI results from myocardial reperfusion injury, subsequent inflammation and coronary endothelial dysfunction. A correlation between peripheral and coronary endothelial function has been suggested and peripheral endothelial dysfunction is associated with the occurrence of cardiovascular events. Therefore we hypothesize a relation between peripheral and coronary endothelial function.

Purpose

The primary aim of our study was to assess the relationship between peripheral endothelial function and microvascular injury in successfully resvascularized STEMI patients.

Methods

Peripheral endothelial function and laboratory values were measured in the acute and stable setting (at 1 year follow-up). Reactive hyperemia-pulse amplitude tomography on the index finger was used to assess peripheral endothelial function by means of the reactive hyperemia index (LnRHI). After revascularization of the culprit vessel, we measured intracoronary coronary flow reserve (CFR). Cardiac magnetic resonance imaging (CMR) at day 5 evaluated the occurrence of MVI defined as microvascular obstruction (MVO) or intramyocardial hemorrhage. Myocardial salvage index (MSI) was calculated as (area at risk − final infarct size) / area at risk.

Results

We included 110 STEMI patients with the age of 60.1±9.5 years. Acute LnRHI was 0.56±0.33 and stable LnRHI was 0.64±0.27 (p=0.070). In the acute setting, LnRHI was impaired in patients with MVI compared to patients without MVI (0.44±0.37 vs. 0.61±0.34, p=0.045). The quantity of MVO (in grams) correlated with acute LnRHI (rho=-0.24, p=0.028). Acute LnRHI correlated to CFR in the revascularized culprit vessel (rho=0.25, p=0.015). In patients with decreased coronary blood flow after successful revascularization (TIMI-flow≤2), stable LnRHI was decreased (0.51±0.36 vs. 0.67±0.24, p=0.019). Stable LnRHI correlated to MSI (rho=0.28, p=0.020). Acute LnRHI correlated to leukocyte count (rho=-0.21, p=0.028) and LDH (rho=-0.25, p=0.018). LnRHI was impaired in patients who were hospitalized during 1 year follow-up (0.45±0.35 vs. 0.66±0.25, p=0.024).

Conclusion(s)

In patients with successfully revascularized STEMI, impaired peripheral endothelial function is associated with microvascular injury, decreased coronary flow and an increased inflammatory status. Furthermore, impaired peripheral endothelial function was associated with the occurrence of clinical events.