A prospective, multi-center, randomised controlled trial for evaluation of the effectiveness of the Blimp scoring balloon in lesions not crossable with a conventional balloon or microcatheter: the BLIMP study

BACKGROUND

Balloon uncrossable coronary lesions are lesions that cannot be crossed with a conventional balloon. Multiple balloons have been designed to overcome this problem. The Blimp balloon has a very low scoring profile (0.6 mm) with a very high rated burst pressure (30 atmospheres). We aimed to evaluate the efficacy of this balloon compared to customary low-profile balloons.

METHODS

We conducted a multicenter, prospective, randomised, controlled trial in which 126 patients with an uncrossable lesion were randomly (1:1 randomization) assigned to treatment first with the Blimp balloon or low-profile balloon. The primary endpoint was the success of crossing the lesion after initial failure with a microcatheter (group A) or with a conventional balloon (group B).

RESULTS

Overall, the first attempt of Blimp was successful in 29 out of 61 cases (48%) while the LP balloon immediately crossed in 30 out 67 cases (45%; p = 0.761). Using a low-profile balloon in the BLIMP group after failure of the Blimp balloon increased the success to 64% (39 out of 61 cases). Using the Blimp balloon in the low-profile first group after failure of the low-profile balloon increased the success to 60% (40 out of 67 cases). After the placement of a guide catheter extension, the overall successful lesion crossing in the BLIMP group was 80% (49 out of 61 cases) compared to 76% (51 out of 67 cases) in the LP Balloon group (p = 0.327).

CONCLUSIONS

The Blimp balloon catheter showed no superiority to customary low-profile balloons in uncrossable lesions. It can however be complementary in treating uncrossable lesions.

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<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.

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<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<0.001; ICC= 0.78 (0.70–0.85) and 0.48 (0.32–0.62), respectively, p<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<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<0.001) and plasma free hemoglobin (PFHb, 4.92±3.82 mg/dL [Rest] and 108.42±46.58 mg/dL [Hyperemia], p<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<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.

Improvement in angina pectoris after percutaneous coronary interventions in focal and diffuse coronary artery disease

Objective

To investigate the effect of PCI on patient-reported outcomes in focal and diffuse coronary artery disease (CAD) as defined by the pullback pressure gradient (PPG).

Background

Improvements in fractional flow reserve (FFR) following PCI are associated with freedom from angina. CAD patterns influence the FFR change after stenting. Therefore, CAD patterns might be essential to assess the likelihood of PCI success in terms of angina relief.

Methods

This is a sub-analysis of the TARGET-FFR randomized clinical trial (NCT03259815). The 7-item Seattle Angina Questionnaire (SAQ-7) and EuroQol five-level EQ-5D questionnaire (EQ-5D-5L) were administered at baseline and three months after PCI. The PPG index was calculated from manual pre-PCI FFR pullbacks and the median PPG value was used to define focal and diffuse CAD.

Results

103 patients (51 with focal and 52 with diffuse disease) were analyzed. There were no differences in baseline characteristics between patients with focal and diffuse CAD. Patients with focal disease had larger increases in FFR with PCI than those with diffuse disease (0.30±0.14 units vs 0.19±0.12 units, p<0.001). Patients who underwent PCI to focal CAD had significantly higher SAQ-7 summary scores at follow-up compared to those with diffuse CAD (87.1±20.3 vs. 75.6±24.4, mean difference 11.5 [95% CI 2.8 to 20.3], p=0.01). Following PCI, residual angina was present in 39.8% of all patients but was significantly lower among those with treated focal CAD (27.5% vs 51.9%, p-value=0.020).

Conclusion

Persistent angina after PCI was almost twice as common in patients with diffuse CAD as defined by the pre-PCI PPG. Patients with focal disease reported greater improvement in angina and quality of life with PCI. The likelihood of successful angina relief from PCI can be predicted by the baseline pattern of CAD.

Funding Acknowledgement

Type of funding sources: None.

Microvascular dysfunction in patients with diabetes mellitus: assessment of absolute coronary flow and microvascular resistance reserve

Background

Coronary microvascular dysfunction (CMD) is an early feature of diabetic cardiomyopathy, which usually precedes the onset of systolic and diastolic dysfunction (DDF). 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 versus non-diabetic patients. Left atrial reservoir strain (LASr), an early marker of DDF 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 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=2.4±0.6 and 2.9±0.8; MRR=2.8±0.9 and 3.5±1 for diabetic and non-diabetic patients respectively, [p<0.05 for both], Figure 1 and 2). 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 DDF 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.

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 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.

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<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<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

Quantifying coronary microvascular disease: assessing absolute microvascular resistance reserve (MRR) by continuous coronary thermodilution

Background and aim

Hyperemic absolute coronary blood flow (in mL/min) can be safely and reproducibly measured with intracoronary continuous thermodilution of saline at room temperature at an infusion rate of 20 mL/min. This study aims at assessing whether continuous thermodilution can also measure resting flow and microvascular resistance.

Methods and results

In 87 coronary arteries (58 patients) with angiographic non-significant stenoses absolute flow was assessed by continuous thermodilution of saline at infusion rates of 10 mL/min and 20 mL/min using a pressure/temperature sensored guide wire, a dedicated infusion catheter and a dedicated software. In addition, in 26 arteries, average peak velocity (APV) was measured simultaneously using an intracoronary Doppler-wire.

There was no significant difference between Pd/Pa at baseline and during saline infusion at 10 mL/min, (0.95±0.053 vs 0.94±0.054, respectively (p=0.53) and there was no significant difference in APV at baseline and during the infusion of saline at 10 mL/min (22.2±8.40 vs 23.2±8.39 cm/s, respectively, p=0.63), thus indicating presence of resting coronary blood flow during the infusion of 10 mL/min of saline.

In contrast, at an infusion rate of 20 mL/min, a significant decrease in Pd/Pa was observed compared to baseline: (0.85±0.089 vs 0.95±0.053, respectively, p<0.001) and a significant increase in APV was observed (22.2±8.4 cm/s to 57.8±25.5 cm/s, respectively, p<0.001). The coronary flow reserve (CFR) calculated by thermodilution and by Doppler flow velocity were similar (2.73±0.85 vs 2.72±1.07, respectively) and their individual values correlated closely (r=0.87, 95% CI 0.72–0.94, p<0,001). Microvascular resistance (Rμ), defined as the distal coronary pressure divided by the absolute flow was calculated both at rest (Rμ-rest) and during hyperemia (Rμ-hyper). Microvascular Resistance Reserve (MRR), is calculated as the ratio of Rμ-rest and Rμ-hyper and showed a good correlation with the analogous Doppler-derived parameter (using the APV instead of absolute flow). Mean doppler and thermodilution derived MRR were similar (3.32±1.50 vs 3.23±1.16) and values correlated closely (r=0.91, 95% CI 0.81 - 0.96, p<0.001; Bland-Altman analysis: mean bias = 0.071, limit of agreement −1.195 to 1.338).

Conclusion

Absolute coronary blood flow (in mL/min) can be measured by continuous thermodilution both at rest and during hyperemia. This allows accurate, reproducible, and operator-independent direct volumetric calculation of CFR and MRR. The latter is a quantitative metric which is specific for microvascular function and independent from myocardial mass.

Doppler and Thermodilution derived MRR

Funding Acknowledgement

Type of funding source: None

Thermodilution-derived resting coronary flow measurement: “a reverse dose finding study”

Background

Hyperemic absolute coronary blood flow (in mL/min) can be safely and reproducibly measured with intracoronary continuous thermodilution of saline at room temperature at an infusion rate of 20 mL/min. This study aims at assessing the best infusion rate to measure resting flow by thermodilution, i.e. low enough to avoid microvascular dilation but high enough to allow reliable thermodilution tracings

Methods and results

In 26 coronary arteries (24 patients) with angiographic non-significant stenoses, absolute flow was assessed by continuous saline thermodilution at infusion rates of 10 mL/min and 20 mL/min using a pressure/temperature sensored guide wire, a dedicated infusion catheter and a dedicated software. Average peak velocity (APV) was measured simultaneously using an intracoronary Doppler-wire. In addition, in a subgroup of 10 arteries, absolute flow and APV were also measured during saline infusion at 6 ml/min and 8 ml/min.

In 26 coronary arteries there was no significance difference in the Pd/Pa and in the APV at baseline and during the infusion of saline at 10 ml/min (Pd/Pa: 0.94±0.057 vs 0.94±0.059, p=0.82; APV: 22.2±8.40 vs 23.2±8.39 cm/s, p=0.63). In contrast, at an infusion rate of 20 mL/min, we observed a significant decrease in Pd/Pa compared to baseline (0.85±0.089 vs 0.95±0.053 vs, respectively, p<0.001) and a significant increase in APV (22.2±8.4 cm/s to 57.8±25.5 cm/s, respectively, p<0.001). The coronary flow reserve (CFR) evaluated by Doppler and intracoronary continuous thermodilution correlated well (r=0.87, 95% CI = 0.72–0.94, p<0.001) and Bland-Altman analysis documented a mean bias of −0.003 (limit of agreement −1.05 to 1.04) thus indicating the presence of resting coronary blood flow during the infusion of 10 mL/min of saline. In 10 coronary arteries saline infusions at 6 and 8 ml/min did not produce any significant changes in the Pd/Pa and in the APV compared to baseline and both Doppler and Thermodilution derived CFR correlated well at each infusion rate (6 ml/min: r=0.71, 95% CI 0.14–0.92, p=0.02; 8ml/min: r=0.78, 95% CI=0.31–0.95, p=0.007). However, with an infusion rate of 6 mL/min, an unstable thermodilution tracing was observed. Accordingly, Bland-Altman analysis showed a significantly larger dispersion of the CFR values when 6 ml/min was used to measure resting coronary flow (as compared with 8 m/min): mean bias at 6 ml/min: −0.53, limits of agreement: −2.25 to 1.20: mean bias at 8 ml/min: 0.004, limits of agreement: −0.72 to 0.73.

Conclusion

Absolute resting coronary flow can be measured by intracoronary continuous thermodilution of saline at infusion rate of 8–10 ml/min.

Funding Acknowledgement

Type of funding source: None

Hyperemic hemodynamic characteristics of serial coronary lesions assessed by pressure pullbacks gradients (PPG) index

Introduction

The evaluation of functional significance in serial coronary lesions is crucial for achieving optimal clinical outcomes. In this setting, fractional flow reserve (FFR) measurements with pullback pressure recording can be helpful in assessing lesion functional significance.

Purpose

To describe the functional characteristics of angiography-defined serial coronary lesions using FFR-derived motorised pullback tracings, and to describe the Pullback Pressure Gradients (PPG) index - in these lesions.

Methods

Prospective, multicentre study with independent core laboratory analysis. Patients undergoing coronary angiography due to stable angina were enrolled. Serial lesions were defined angiographically as the presence of 2 or more narrowings with visual diameter stenosis >50% separated at least by 3 times the reference vessel diameter in the same coronary vessel. Continuous IV adenosine-FFR measurements were obtained using a motorised device at a speed of 1 mm/s. Pullback curves were assessed to determine the presence of focal step-ups (FFR >0.05 units over 20 mm). In addition, the PPGindex was computed for all vessels. PPGindex values close to 0 define functional diffuse disease whereas values close to 1 define focal disease.

Results

From a total of 159 vessels (117 patients), 25 vessels were adjudicated as presenting serial lesions (mean PPGindex 0.48±0.17, range 0.26–0.87). Two focal pressure step-ups were observed in 40% of the cases (n=10; mean PPGindex 0.59±0.17), whereas 8% of the vessels presented a progressive pressure losses (n=2; mean PPGindex 0.27±0.01). In the remaining 52% of the cases, a single pressure step-up was recorded (n=13; mean PPGindex 0.44±0.12; ANOVA p-value = 0.01). The PPGindex independently predicted the presence of two focal pressure step ups.

Conclusion

Hyperemic FFR curves in tandem stenoses revealed high prevalence of functional diffuse CAD. Two pressure step-ups occurred in less than half of the vessels. High PPG-Index identified vessels with two focal pressure drops. FFR tracings and the PPGindex provide a more objective CAD evaluation, which can lead to changes in the therapeutic approach.

Funding Acknowledgement

Type of funding source: None

Quantification of calcium volume by coronary CT compared to OCT

Background

Coronary artery calcifications are frequently observed in patients referred for cardiac catheterization. Using OCT, the calcified volume can be determined. CT is a sensitive non-invasive tool to detect coronary artery calcifications and may be useful to guide percutaneous coronary intervention.

Purpose

The aim of the study was to investigate the accuracy of CT-derived calcium volume with OCT as a reference in patients undergoing PCI.

Methods

66 calcified plaques (32 vessels) from 31 patients undergoing OCT-guided PCI with coronary CT angiography acquired as a standard of care were included. Coronary CT angiography and OCT images were matched using fiduciary points. Calcified plaques were reconstructed in three dimensions to calculate calcium volume. A Passing-Bablok regression analysis and the Bland-Altman method were used to assess agreement between imaging modalities.

Results

27 left anterior descending arteries and 5 right coronary arteries were analyzed. Median calcium volume by CT angiography and OCT were 18.23 mm 3 [IQR 8.09, 36.48] and 10.03 mm 3 [IQR 3.6, 22.88]. The Passing-Bablok analysis showed a proportional difference without a systematic difference (Coefficient A 0.08, 95% CI: −1.37 to 1.21, Coefficient B 1.61, 95% CI: 1.45 to 1.84); with a mean difference of 9.69 mm3 (LOA −10.2 mm 3 to 29.6 mm 3). No significant differences were observed for MLA: median value for CT 2.84 mm2 [IQR 2.03, 3.74] and for OCT 2.55 mm2 [IQR 1.91, 4.43].

Conclusions

Coronary CT angiography volumetric calcium evaluation overestimates calcium volume by 60% compared to OCT. Accounting for CT overestimation may allow for appropriate interpretation of calcific burden in the non-invasive setting. Coronary CT angiography may emerge as a tool to quantify calcium burden for invasive procedural planning.

Calcium burden comparison CT vs OCT

Funding Acknowledgement

Type of funding source: None

1156Coronary artery bypass grafting vs. FFR-guided PCI in diabetic patients with multivessel disease

Background

In diabetic patients with multivessel coronary disease (MVD), coronary artery bypass grafting (CABG) has shown long-term benefits in mortality over percutaneous coronary revascularization (PCI). Nevertheless, the impact of fractional flow reserve (FFR)-guided PCI on clinical outcomes has never been investigated in these patients.

Purpose

To evaluate the long-term (5-year) clinical outcome of diabetic patients with MVD treated with FFR-guided PCI compared to CABG.

Methods

From February 2010 to February 2018, all diabetic patients undergoing coronary angiography in one centre (n=4622) were screened for inclusion. The inclusion criterion was presence of at least two-vessels CAD defined as with diameters stenosis ≥50%. In case of intermediate coronary stenosis (%DS 30–70%), FFR was performed at the discretion of the operator. Revascularization was performed when FFR ≤0.80. Exclusion criteria were ST-elevation myocardial infarction, prior CABG, and moderate or severe valvular heart dysfunction.

To account for confounders, we compared outcomes by calculating an adjusted Kaplan-Meier estimator using inverse probability of treatment weighting (IPTW). Propensity score variables included age, sex, smoking habit, hypertension, hyperlipidemia, insulin therapy, family history of CAD, chronic obstructive pulmonary disease (COPD), glomerular filtration rate (GFR), prior myocardial infarction, peripheral vascular disease (PVD), admission for NSTEMI, ejection fraction, number of angiographic stenotic vessels. Odds ratios were calculated using generalized linear models (GLM). The primary endpoint was major adverse cardiovascular and cerebrovascular events (MACCE), defined as all-cause death, myocardial infarction and stroke. Secondary endpoints were the individual component of MACCE and any repeated revascularization.

Results

A total of 538 diabetic patients with MVD were included in the analysis. Among them, 317 (59%) patients underwent CABG and 221 (41%) FFR-guided PCI.

Patients treated with FFR-guided PCI had more often COPD as compared to patients in the CABG-group, but patients treated with CABG had lower GFR, more PVD, higher number of angiographic stenotic vessels (2.8±0.4 vs. 2.5±0.5; p<0.01) and higher Syntax score (20±7 vs. 14±6; p<0.01) as compared to the FFR-guided PCI group.

Clinical follow-up was obtained in 95% of the patients at a median follow-up of 5 years.

The incidence of MACCE was similar in the CABG and in the FFR-guided PCI group [27% vs. 29%; OR (95% CI) 1.05 (0.68–1.63); p=0.74]. No differences were found in the individual components of MACCE. Repeat revascularization was more frequent in the FFR-guided PCI group than in the CABG group [27% vs. 7%; OR (95% CI) 4.3 (2.35–7.9); p<0.01].

Conclusions

In diabetic patients with MVD undergoing FFR-guided PCI, no differences in major adverse events were observed at a median follow-up of 5 years compared with CABG.

279Clinical outcome after coronary bifurcation stenting: a systematic review and network meta-Analysis of PCI bifurcation techniques comprising 5572 patients

Background

The optimal PCI technique for bifurcation lesions remains a matter of debate. Several RCT have compared different bifurcation PCI techniques. Provisional stenting has been recommended as the default technique for most bifurcation lesions. However, emerging data suggests that double-kissing crush technique can be considered in true left main bifurcation lesions and has been endorsed by the European Society of Cardiology Guidelines.

Purpose

To compare the clinical outcome between different bifurcation PCI techniques.

Methods

We searched MEDLINE for randomized clinical trials (RCT) comparing PCI bifurcation techniques for coronary bifurcation lesions. Outcomes of interest were major adverse cardiovascular events (MACE) defined as the composite of cardiac death, myocardial infarction (MI) and target vessel or lesion revascularization (TVR/TLR), and the individual components of MACE. Stent thrombosis was assessed as defined by the ARC. Stratification based on left-main or distal bifurcations was performed. We evaluated the studies' risk of bias in accordance to the Cochrane Handbook for Systematic Reviews of Interventions, and certainty of evidence using the Grading of Recommendations Assessment, Development and Evaluation framework. We estimated summary odds ratios (ORs) using pairwise and Bayesian network meta-analysis.

Results

We identified 263 studies and of these included 19 RCT including 5572 patients treated with 5 bifurcation PCI techniques namely provisional stenting, systematic T-stenting, crush, culotte and double-kissing crush. Median follow-up was 12 months (IQR 8 to 36). When all bifurcation lesions were combined, double-kissing crush technique reduced the occurrence of MACE (OR 0.42; CrI 0.28 to 0.61) compared to provisional stenting. This difference was driven by a reduction in TVR/TLR (OR 0.39; CrI 0.25 to 0.65). No differences were found in cardiac death, MI or stent thrombosis among analyzed PCI techniques. No differences in MACE were observed between provisional stenting, systematic T-stenting, crush. In distal bifurcations (n=17 studies, 4634 patients), double-kissing crush also showed to reduce MACE (OR 0.48; CrI 0.29 to 0.67 vs. Provisional). In left-main bifurcations (n=3 studies, 938 patients) no differences in MACE were found between PCI techniques.

Conclusions

In this network meta-analysis, PCI bifurcation techniques were similar with respect to the occurrence of cardiac death, myocardial infarction and stent thrombosis. When all coronary bifurcations were combined, an advantage of double-kissing crush was observed in terms of MACE driven by lower rate of repeated revascularization. Further studies are required to define the best PCI bifurcation technique for left main coronary artery disease.

P855Evaluation of epicardial coronary resistance using computed tomography angiography

Background

A Fractional flow reserve (FFR) pullback allows assessing the distribution of pressure loss along the vessel. FFR derived from CT (FFRCT) provides a virtual pullback curve that may also aid in the assessment of epicardial coronary resistance in the non-invasive setting.

Purpose

The present study aims to determine the accuracy of the virtual FFRCT pullback curve using a motorized invasive FFR pullback as reference in patients with stable coronary artery disease.

Methods

This is a single centre, prospective study of patients with stable coronary artery disease in whom FFRCT was performed as standard of care for non-invasive assessment. Patients referred to coronary angiography with clinically indicated invasive FFR measurement were included. FFRCT and invasive FFR values were extracted from coronary vessels every 1 mm to generate pullback curves. Invasive FFR pullbacks were acquired using a dedicated device at a speed of 1 mm/s. The area under the pullback curve (AUPC), defined as the sum of areas under the FFR pullback curve, was compared between FFRCT and invasive FFR pullbacks. Lesions were defined based on invasive angiography. FFR gradients in lesions and non-obstructive segments were defined as the difference between FFR values at the proximal and distal edge of the segments. FFR vessel gradient was defined as the difference between the most distal FFR value and the FFR at the ostium of the vessel. Mixed effect model was used to account for the correlation of FFR values within vessels. The agreement between FFRCT and FFR gradients was assessed using the Passing Bablok regression analysis and Bland-Altman methods at the vessel, lesion and non-obstructive level.

Results

A total of 3172 matched FFRCT and FFR values were obtained in 24 vessels. The correlation coefficient between FFRCT and FFR was 0.76 (95% CI 0.75 to 0.78; p<0.001). The mean difference between the FFRCT and invasive FFR pullback values was 0.07 (LOA −0.11 to 0.24). AUPC was similar between FFRCT and invasive FFR (79.0±16.1 vs. 85.3±16.4, p=0.097); the mean slope of FFRCT pullback curve was steeper compared to invasive FFR (p<0.001). The mean difference in lesion gradient was −0.07 (LOA −0.26 to 0.13) and −0.01 (LOA −0.06 to 0.05) in non-obstructive segments. There were no systematic or proportional differences between FFRCT and FFR gradients either in lesion or non-obstructive segments); however, vessel gradients were overestimated by FFRCT with a bias of −0.12 (LOA −0.35 to 0.12) driven by a higher mean difference in lesion gradients (−0.07; 95% CI −0.26 to 0.13).

Conclusions

The evaluation of epicardial coronary resistance using coronary CT angiography with FFRCT was feasible. FFRCT pullbacks were accurate in the assessment of lesion and non-obstructive gradients. FFRCT can identify the physiological pattern of coronary artery disease in the non-invasive setting.

Air pollution and ST-elevation myocardial infarction: A case-crossover study of the Belgian STEMI registry 2009-2013

BACKGROUND

Previous studies have shown that air pollution particulate matter (PM) is associated with an increased risk for myocardial infarction. The effects of air pollution on the risk of ST-elevation myocardial infarction (STEMI), in particular the role of gaseous air pollutants such as NO₂ and O₃ and the susceptibility of specific populations, are still under debate.

METHODS

All patients entered in the Belgian prospective STEMI registry between 2009 and 2013 were included. Based on a validated spatial interpolation model from the Belgian Environment Agency, a national index was used to address the background level of air pollution exposure of Belgian population. A time-stratified and temperature-matched case-crossover analysis of the risk of STEMI was performed.

RESULTS

A total of 11,428 STEMI patients were included in the study. Each 10μg/m³ increase in PM10, PM2.5 and NO₂ was associated with an increased odds ratio (ORs) of STEMI of 1.026 (CI _95%: 1.005-1.048), 1.028 (CI _95%: 1.003-1.054) and 1.051 (CI _95%: 1.018-1.084), respectively. No effect of O₃ was found. STEMI was associated with PM10 exposure in patients ≥75y.o. (OR: 1.046, CI _95%: 1.002-1.092) and with NO₂ in patients ≤54y.o. (OR: 1.071, CI _95%: 1.010-1.136). No effect of air pollution on cardiac arrest or in-hospital STEMI mortality was found.

CONCLUSION

PM2.5 and NO₂ exposures incrementally increase the risk of STEMI. The risk related to PM appears to be greater in the elderly, while younger patients appear to be more susceptible to NO₂ exposure.

The neurotoxicity and safety of treatment with cefepime in patients with renal failure

BACKGROUND

Cases of cefepime neurotoxicity have been sporadically reported in patients with renal failure. The neurotoxicity of cefepime might be underestimated and the frequency of its neurotoxic effects may be insufficiently recognized.

METHODS

We retrospectively reviewed the files of patients with renal failure who were treated with cefepime and who developed neurological complications.

RESULTS

All 8 patients developed decreased conscience, confusion, agitation, global aphasia, myoclonus, chorea-athetosis, convulsions and coma. The latency, the period between the start of treatment and neurological deterioration, was 4,75 +/- 2,55 days (range: 1-10 days). All patients died 17 +/- 14,7 days (range: 1-42 days) after becoming symptomatic. Three of them died shortly after neurological deterioration. Five patients developed a neurological "tableau" with global aphasia. Three patients showed clinical improvement after the discontinuation of cefepime. Electroencephalography revealed diffuse slow-wave activity (delta) and triphasic sharp wave activity. These findings confirm the possible neurotoxicity of treatment with cefepime in patients with renal failure. In none of the deceased patients have we been able to directly demonstrate a causal relationship between neurotoxicity and mortality. However, when a patient treated with cefepime develops neurological deterioration or aphasia, one must be aware of cefepime's potential neurotoxicity and treatment should be stopped.

CONCLUSION

We recommend that, in view of the high and unexplained mortality, the use of cefepime in patients with kidney failure should be carefully considered.