Assessment of Cardiovascular Risk by the Combination of Clinical Risk Scores Plus Platelet Expression of FcγRIIa.

Platelet expression of FcγRIIa was quantified after myocardial infarction (MI) and we found that patients with high platelet FcγRIIa expression (>11,000/platelet) had a fourfold greater risk of subsequent MI, stroke, and death. This analysis of the original cohort of 197 patients was designed to determine whether platelet expression of FcγRIIa could be used in combination with clinical risk scores (GRACE [Global Registry of Acute Coronary Events] and DAPT [Dual Antiplatelet Therapy]) to refine cardiovascular risk assessment. Platelet expression of FcγRIIa quantified with the use of flow cytometry was broadly distributed in patients stratified into high and low risk groups based on clinical risk scores. In patients identified as high risk by the GRACE score, 62% had high platelet FcγRIIa expression. Similarly, in patients identified as high risk by DAPT, 55% had high platelet FcγRIIa expression. High platelet FcγRIIa expression discriminated high and low risk cohorts in patients with high cardiovascular risk defined by either the GRACE score (high platelet FcγRIIa 18.9% vs low platelet FcγRIIa 0%; odds ratio = 15.7, p = 0.06) or the DAPT score (high platelet FcγRIIa 15.4% vs low platelet FcγRIIa 3.7%; odds ratio = 5.6, p = 0.03) assessment. Platelet expression of FcγRIIa merits additional study to determine whether low platelet FcγRIIa expression can be used to guide early transition to aspirin monotherapy and high platelet FcγRIIa expression can be used to guide continuation of DAPT.

Variation in platelet expression of FcγRIIa after myocardial infarction.

FcγRIIa amplifies platelet activation and greater platelet expression of FcγRIIa identifies patients at greater risk of subsequent cardiovascular events. Thus, platelet expression of FcγRIIa may be useful to guide therapy. Because platelet function tests are impacted by preparative procedures and substantial intra-individual variability, we examined the impact of these factors on platelet expression of FcγRIIa in blood from healthy subjects and in patients after myocardial infarction (MI). Platelet expression of FcγRIIa was quantified with the use of flow cytometry. Blood was taken from healthy subjects and 114 patients after a MI in whom platelet expression of FcγRIIa was quantified before discharge and at 6 ± 1 months. Neither anticoagulants nor the antiplatelet agent cangrelor changed platelet expression of FcγRIIa. Intra-individual variation in platelet FcγRIIa expression was 8.5% ± 5% over the course of 1 month in healthy subjects. Platelet FcγRIIa expression was within 20% of the baseline value after 6 months in 71% of patients after MI. In summary, because FcγRIIa is a protein on the surface of platelets, assay conditions and antiplatelet agents do not change expression. Intra-individual variability in platelet expression of FcγRIIa is modest. Accordingly, platelet expression of FcγRIIa is a marker of increased platelet reactivity that can be reliably and repeatedly measured.Clinical Trial Registration: NCT02505217.

Factors influencing platelet reactivity in patients undergoing coronary artery bypass surgery.

OBJECTIVE: Because coronary artery bypass graft (CABG) surgery is associated with a high turnover of platelets, assessment of platelet function should enable assessment of the effect of young (RNA-containing) platelets on platelet reactivity. This study was designed to assess platelet reactivity 1 day after CABG in patients treated previously with clopidogrel or ticagrelor. METHODS: Patients (n=18) with acute coronary syndrome who required urgent CABG and had been treated for up to 2 days before surgery with aspirin plus clopidogrel (n=13) or aspirin plus ticagrelor (n=5) were enrolled. Care was not altered by participation, which entailed review of medical records and taking one sample of blood 1 day after surgery. The percentage of RNA-containing platelets was quantified using thiazole orange, and platelet function was assessed by flow cytometry. RESULTS: Young platelets constituted, on average, 24% of platelets (range 4-54%) and were more likely to be activated in the absence or presence of an agonist (P<0.001). Differences between RNA-containing (young) and non-RNA-containing platelets were evident in patients treated previously with clopidogrel (P<0.001), whereas a nonsignificant trend was apparent in patients treated previously with ticagrelor. A high but variable prevalence of young platelets was seen 1 day after CABG. CONCLUSION: Young platelets were more reactive and, consistent with the irreversible binding of clopidogrel to P2Y12, this effect was more pronounced after treatment with clopidogrel. The reversible binding of ticagrelor to the platelet P2Y12 receptor may be advantageous in patients with a high platelet turnover.

Mechanisms of Heart Block after Transcatheter Aortic Valve Replacement - Cardiac Anatomy, Clinical Predictors and Mechanical Factors that Contribute to Permanent Pacemaker Implantation.

Transcatheter aortic valve replacement (TAVR) has emerged as a valuable, minimally invasive treatment option in patients with symptomatic severe aortic stenosis at prohibitive or increased risk for conventional surgical replacement. Consequently, patients undergoing TAVR are prone to peri-procedural complications including cardiac conduction disturbances, which is the focus of this review. Atrioventricular conduction disturbances and arrhythmias before, during or after TAVR remain a matter of concern for this high-risk group of patients, as they have important consequences on hospital duration, short- and long-term medical management and finally on decisions of device-based treatment strategies (pacemaker or defibrillator implantation). We discuss the mechanisms of atrioventricular disturbances and characterise predisposing factors. Using validated clinical predictors, we discuss strategies to minimise the likelihood of creating permanent high-grade heart block, and identify factors to expedite the decision to implant a permanent pacemaker when the latter is unavoidable. We also discuss optimal pacing strategies to mitigate the possibility of pacing-induced cardiomyopathy.

A regional pharmacoinvasive PCI strategy incorporating selected bleeding avoidance strategies.

BACKGROUND: Pharmacoinvasive therapy (PIT) is a potential treatment for ST-segment elevation myocardial infarction patients who are not able to achieve primary percutaneous intervention (PCI) within guideline-recommended time limits. The risk for bleeding complications with PIT has not been studied in the setting of routine use of two selected bleeding avoidance strategies (BAS): bivalirudin and vascular closure devices. METHODS: We analyzed a contemporary multicenter registry (2009-2013) of consecutive patients undergoing PCI as part of a 10-hospital regional algorithm involving one PCI center and nine transfer centers: PIT for hospitals greater than 60 min (N=140), and primary PCI if less than 60-min travel time to the PCI center (N=346). We compared the risk for Harmonizing Outcomes With Revascularization and Stents in Acute Myocardial Infarction (HORIZONS) major bleeding among patients undergoing PIT versus primary PCI in the setting of routine use of selected BAS and determined the independent predictors of major bleeding in the entire cohort. RESULTS: The PIT patients had a median travel time of 103±49 min, were more frequently female, had a higher incidence of renal failure, and had a lower frequency of cardiogenic shock compared with the primary PCI group. BAS were routine and similar in both groups. Rates of death, stroke, and ischemic and major bleeding outcomes were similar between the two groups, and the length of stay was shorter in the PIT group. Multivariate logistic models indicated that two independent predictors of major bleeding were cardiac arrest [odds ratio (OR)=3.89, 95% confidence interval (CI): 1.2-12.1, P=0.02] and bailout glycoprotein IIb/IIIa inhibitor utilization (OR=3.29, 95% CI: 1.1-9.6, P=0.03). The PIT strategy in conjunction with selected BAS did not predict major bleeding (OR=2.1, 95% CI: 0.85-5.44, P=0.11). CONCLUSION: Bleeding and ischemia rates were similar between the PIT and primary PCI strategies in the setting of routine use of selected BAS; further study on a broader range of BAS including the radial approach may be warranted. Cardiac arrest and bailout glycoprotein IIb/IIIa inhibitor, but not PIT in conjunction with selected BAS, are independent predictors of bleeding risk in a regional ST-segment elevation myocardial infarction population.