Impact of alirocumab added to high-intensity statin therapy on platelet function in AMI patients: a pre-specified substudy of the randomized, placebo-controlled PACMAN-AMI trial

Background

Previous small observational studies have suggested a potential association of proprotein convertase subtilisin kexin type 9 (PCSK9) and platelet reactivity. However, the role of the PCSK9 inhibitor alirocumab on platelet aggregation among patients with acute myocardial infarction (AMI) remains unknown.

Purpose

We investigated the effect of alirocumab on P2Y12 reaction unit (PRU) on top of high-intensity statin therapy among AMI patients receiving dual antiplatelet therapy (DAPT) with a potent P2Y12 inhibitor (ticagrelor or prasugrel).

Methods

This was a pre-specified, powered, pharmacodynamic substudy nested within the PACMAN (effects of the PSCK9 antibody AliroCuMab on coronary Atherosclerosis in patieNts with Acute Myocardial Infarction) trial, a randomized, double-blind trial comparing biweekly alirocumab (150mg) versus placebo in AMI patients undergoing percutaneous coronary intervention (PCI). Patients recruited at Bern University Hospital, receiving DAPT with either ticagrelor or prasugrel at 4 weeks and adherent to the study drug (alirocumab or placebo) were analyzed for the current study. The VerifyNow P2Y12 point-of-care assays were used to measure PRU at baseline (i.e. before first study drug administration), 4 weeks, and 52 weeks after study drug administration (higher PRU levels indicating greater platelet aggregation). The primary endpoint was PRU at 4 weeks.

Results

Among 139 randomized patients (mean age 58.2 years [SD, 9.5], 21 [15.0%] women, mean LDL-C level 150.6mg/dL [SD, 30.9]), baseline characteristics were well balanced between groups including baseline PRU (50.0 [IQR, 120.0] in the alirocumab group vs. 62.0 [IQR, 122.0] in the placebo group, P=0.75). At 4 weeks, mean LDL-C was significantly lower in the alirocumab group (23.5 [SD, 23.7] mg/dL vs. 74.4 [SD, 30.5] mg/dL, P<0.001). The majority of patients received ticagrelor DAPT at 4 weeks (57 [86.4%] vs. 69 [94.5%], P=0.14). There were no significant differences in PRU at 4 weeks (12.5 [IQR, 27.0] vs. 19.0 [IQR, 30.0], P=0.26) and at 52 weeks (25.0 [IQR, 37.0] vs. 34.0 [IQR, 59.0], P=0.07) (Figure). Consistent results were observed in 126 patients treated with ticagrelor (i.e. after excluding 13 patients treated with prasugrel) at 4 weeks (13.0 [IQR, 20.0] vs. 18.0 [IQR, 27.0], P=0.28).

Conclusion

Among AMI patients receiving DAPT with potent P2Y12 inhibitors, alirocumab had no significant effect on platelet function as assessed by PRU.

Funding Acknowledgement

Type of funding sources: Public Institution(s). Main funding source(s): Bern University Hospital

Frequency and prognostic impact of periprocedural myocardial infarction determined by various MI definitions in patients with chronic coronary syndromes undergoing percutaneous coronary intervention

Background

Several definitions of peri-procedural myocardial infarction (MI) requiring different biomarker thresholds with or without ancillary criteria for myocardial ischemia are currently recommended without being fully validated in real-world patients with chronic coronary syndrome (CCS) undergoing percutaneous coronary intervention (PCI).

Objectives

We aimed to evaluate the prevalence and prognostic value of high-sensitivity cardiac troponin-based peri-procedural MI according to contemporary MI definitions using a large real-world PCI cohort.

Methods

In CCS patients undergoing elective PCI enrolled to the Bern PCI registry (NCT02241291) between 2010 and 2018, peri-procedural myocardial injury and infarction were assessed according to the 4th and 3rd universal definition of MI (UDMI), academic research consortium (ARC)-2, and Society for Cardiovascular Angiography and Interventions (SCAI) criteria. The primary endpoint was cardiac death at 1 year.

Results

Among 4404 CCS patients, peri-procedural MI defined by the 4th UDMI, 3rd UDMI, ARC-2, and SCAI were observed in 14.9%, 18.0%, 2.0%, and 2.0% of patients, respectively. Cardiac mortality at 1 year in patients with peri-procedural MI defined by 4th UDMI, 3rd UDMI, ARC-2, and SCAI were 3.0%, 2.9%, 5.8%, and 10.0%, respectively. After multivariate adjustments, peri-procedural MI defined by the ARC-2 and SCAI were independently associated with cardiac death at 1 year, while those defined by the 4th and 3rd UDMI were not.

Conclusion

Among CCS patients undergoing PCI, periprocedural MIs defined by theARC-2 and SCAI occurred 7 to 9 times less frequently as compared with the 4th and 3rd UDMI, and were the only definitions significantly associated with cardiac mortality.

Funding Acknowledgement

Type of funding sources: None. Cardiac death at 1 year

Functional assessment of myocardial ischemia by intracoronary electrocardiogram

Background

In patients with chronic coronary syndrome (CCS), percutaneous coronary intervention (PCI) targets hemodynamically significant stenoses, i.e., those thought to cause ischemia. The hemodynamic severity of a coronary stenosis increases with its tightness and with the myocardial mass of viable myocardium downstream of the stenosis. Besides the structural angiographic approach, assessment of functional relevance by pressure measurements (fractional flow reserve, FFR; instantaneous wave-free ratio, iFR) is recommended. However, visual angiographic assessment continues to dominate the treatment decisions for intermediate coronary lesions. Conversely, intracoronary ECG (icECG) potentially provides an inexpensive, sensitive and direct measure of myocardial ischemia.

Purpose

The goal of this study was to test the accuracy of intracoronary ECG during pharmacologic inotropic stress to determine coronary lesion severity in comparison to established physiologic indices (FFR/iFR) as well as with quantitatively determined percent diameter stenosis (%S) using biplane coronary angiography.

Method

This was a prospective, open-label study in patients with CCS. The primary study end point was the maximal change in icECG ST-segment shift during pharmacologic inotropic stress induced by dobutamine plus atropine obtained within 1 minute after the point of maximal heart rate (estimated by the formula 220 - age). IcECG was acquired by attaching an alligator clamp to the angioplasty guidewire positioned downstream of a stenosis. For the pressure-derived ratios, i.e. FFR and iFR, the coronary perfusion pressure downstream of a lesion as well as the aortic pressure were continuously recorded.

Results

One hundred patients were included in the study. Pearson-Correlation coefficient was significant between icECG and all three comparators (%S p<0.001, iFR p<0.001, FFR p<0.001). Using the FFR threshold of 0.80 defining coronary hemodynamic significance, ROC-analysis of the absolute icECG ST-segment shift showed an area under the curve (AUC) of 0.708±0.053 (p=0.0001, n=100, FFR<0.80 n=41). AUC for iFR was 0.919±0.030 (p<0.0001), for percent diameter stenosis it was 0.867±0.036 (p<0.0001).

Conclusions

During pharmacologic inotropic stress, intracoronary ECG ST-segment shift provides specific evidence for regional myocardial ischemia irrespective of the etiology and thus, provides an additional (patho-)physiologic information for decision making in borderline coronary lesions.

Funding Acknowledgement

Type of funding source: Foundation. Main funding source(s): Swiss Heart Foundation

Vortex formation and recirculation zones in left anterior descending artery stenoses: computational fluid dynamics analysis

Flow patterns may affect the potential of thrombus formation following plaque rupture. Computational fluid dynamics (CFD) were employed to assess hemodynamic conditions, and particularly flow recirculation and vortex formation in reconstructed arterial models associated with ST-elevation myocardial infraction (STEMI) or stable coronary stenosis (SCS) in the left anterior descending coronary artery (LAD). Results indicate that in the arterial models associated with STEMI, a 50% diameter stenosis immediately before or after a bifurcation creates a recirculation zone and vortex formation at the orifice of the bifurcation branch, for most of the cardiac cycle, thus allowing the creation of stagnating flow. These flow patterns are not seen in the SCS model with an identical stenosis. Post-stenotic recirculation in the presence of a 90% stenosis was evident at both the STEMI and SCS models. The presence of 90% diameter stenosis resulted in flow reduction in the LAD of 51.5% and 35.9% in the STEMI models and 37.6% in the SCS model, for a 10 mmHg pressure drop. CFD simulations in a reconstructed model of stenotic LAD segments indicate that specific anatomic characteristics create zones of vortices and flow recirculation that promote thrombus formation and potentially myocardial infarction.