Transcoronary electrophysiological parameters in patients undergoing elective and acute coronary intervention.

INTRODUCTION: Percutaneous coronary intervention is performed routinely in the management of myocardial infarction with obstructive coronary disease, but intervention to arteries supplying nonviable myocardium may be harmful. It is important therefore to establish myocardial viability, and there is an unmet need in current clinical practice for real time viability assessment to aid in decision making. Transcoronary pacing to assess myocardial electrophysiological parameters may be a novel viability assessment technique which could be used in this regard. METHODS: Coronary intervention was carried out according to standard departmental procedure with standard equipment. An exchange length coronary guidewire was passed into both target and reference coronary vessels and an over-the-wire balloon or microcatheter was used to insulate the guidewire and allow electrophysiological parameters to be assessed. Readings were obtained from all major epicardial vessels and substantial branches. At each position, an intracoronary electrocardiogram was recorded, and R wave amplitude was measured. Transcoronary pacing was then performed to establish threshold and impedance for each myocardial segment. A viability cardiac MRI scan was performed for each patient. A standard segmental model was used to determine viability in each segment using an 'infarct score' based on degree of late gadolinium enhancement. Studies were reported blinded to the electrical parameters obtained from the coronary guidewire. The primary outcome was the relationship between pacing threshold and myocardial segment infarct score. Secondary outcomes included the relationship between segmental infarct score and R wave height, and between segmental infarct score and pacing impedance. Data were collected on the feasibility of studying the coronary segments as well as safety. RESULTS: Sixty-five patients presenting with stable coronary artery disease or acute coronary syndromes to Leeds General Infirmary between September 2019 and August 2021 were included in the study. Electrophysiological parameters from segments with an infarct score of zero were obtained, with wide variances seen, with no significant difference in impedance or threshold in any territory. There was a significant difference in sensitivity for segments in the right coronary artery territory for both elective and acute patients. This likely relates to reduced myocardial mass in these territories. No significant association between infarct score and sensitivity, impedance or threshold were seen. CONCLUSION: This study has established intracoronary electrophysiological parameters in both normal myocardium and areas of myocardial scar. No reliable association was seen between impedance, threshold or R wave amplitude and degree of myocardial viability, contrasting with prior findings from our group and others. More work is therefore required to fully understand the role of transcoronary pacing in this setting.

Fractional Flow Reserve versus Angiography-Guided Management of Coronary Artery Disease: A Meta-Analysis of Contemporary Randomised Controlled Trials.

Background and Aims: Randomised controlled trials (RCTs) comparing outcomes after fractional flow reserve (FFR)-guided versus angiography-guided management for obstructive coronary artery disease (CAD) have produced conflicting results. We investigated the efficacy and safety of an FFR-guided versus angiography-guided management strategy among patients with obstructive CAD. Methods: A systematic electronic search of the major databases was performed from inception to September 2022. We included studies of patients presenting with angina or myocardial infarction (MI), managed with medications, percutaneous coronary intervention, or bypass graft surgery. A meta-analysis was performed by pooling the risk ratio (RR) using a random-effects model. The endpoints of interest were all-cause mortality, MI and unplanned revascularisation. Results: Eight RCTs, with outcome data from 5077 patients, were included. The weighted mean follow up was 22 months. When FFR-guided management was compared to angiography-guided management, there was no difference in all-cause mortality [3.5% vs. 3.7%, RR: 0.99 (95% confidence interval (CI) 0.62−1.60), p = 0.98, heterogeneity (I2) 43%], MI [5.3% vs. 5.9%, RR: 0.93 (95%CI 0.66−1.32), p = 0.69, I2 42%], or unplanned revascularisation [7.4% vs. 7.9%, RR: 0.92 (95%CI 0.76−1.11), p = 0.37, I2 0%]. However, the number patients undergoing planned revascularisation by either stent or surgery was significantly lower with an FFR-guided strategy [weighted mean difference: 14 (95% CI 3 to 25)%, p =< 0.001]. Conclusion: In patients with obstructive CAD, an FFR-guided management strategy did not impact on all-cause mortality, MI and unplanned revascularisation, when compared to an angiography-guided management strategy, but led to up to a quarter less patients needing revascularisation.

Safety and efficacy of interrupting dual antiplatelet therapy one month following percutaneous coronary intervention: a meta-analysis of randomized controlled trials.

Very short duration of dual antiplatelet therapy (DAPT) following percutaneous coronary intervention (PCI) has recently attracted a lot of attention with the introduction of newer generations stents. This is appealing, especially in patients at high bleeding risk. However, none of the trials were powered for the individual ischemic and bleeding endpoints. All randomised controlled trials (RCTs) investigating one-month versus routine duration of DAPT in patients undergoing PCI and reporting outcomes from the time of cessation of DAPT (1 month) to 1 year were eligible for inclusion in the meta-analysis. The pooled risk ratios (RR) with their 95% confidence interval (CI) were calculated with the random-effects model using the Mantel-Haenszel method. Four RCTs involving 26,576 patients were included in this meta-analysis. Cessation of DAPT after 1 month was associated with significantly less major bleeding [RR 0.70, 95%CI (0.51-0.95), P = 0.02, heterogeneity (I2) = 42%]. There was no statistically significant difference in all-cause mortality [RR 0.84 (95%CI 0.69-1.03), P = 0.10, I2 = 0%] and stroke [RR 0.71 (95%CI 0.45-1.13), P = 0.15, I2 = 42%] when compared to routine duration of DAPT. There was also no difference in myocardial infarction (MI) [RR 1.12 (95%CI 0.91-1.39), P = 0.28, I2 = 0%], and definite or probable stent thrombosis [RR 1.49 (95%CI 0.92-2.41), P = 0.11, I2 = 0%] with cessation of DAPT after 1 month. Cessation of DAPT 1 month after PCI was associated with significantly less major bleeding, but there was no difference in the rate of all-cause mortality, stroke, MI and stent thrombosis.

Systematic review and meta-analysis of optimal P2Y12 blockade in dual antiplatelet therapy for patients with diabetes with acute coronary syndrome.

BACKGROUND: Patients with diabetes are at increased risk of acute coronary syndromes (ACS) and their mortality and morbidity outcomes are significantly worse following ACS events, independent of other comorbidities. This systematic review sought to establish the optimum management strategy with focus on P2Y12 blockade in patients with diabetes with ACS. METHODS: MEDLINE (1946 to present) and EMBASE (1974 to present) databases, abstracts from major cardiology conferences and previously published systematic reviews were searched to June 2014. Relevant randomised control trials with clinical outcomes for P2Y12 inhibitors in adult patients with diabetes with ACS were scrutinised independently by 2 authors with applicable data was extracted for primary composite end point of cardiovascular death, myocardial infarction (MI) and stroke; enabling calculation of relative risks with 95% CI with subsequent direct and indirect comparison. RESULTS: Four studies studied clopidogrel in patients with diabetes, with two (3122 patients) having primary outcome data showing superiority of clopidogrel against placebo with RR0.84 (95% CI 0.72-0.99). Irrespective of management strategy, the newer agents prasugrel (2 studies) and ticagrelor (1 study) had a lower primary event rate compared with clopidogrel; RR 0.80 (95% CI 0.66 to 0.97) and RR 0.89 (95% CI 0.77 to 1.02), respectively. When ticagrelor was indirectly compared with prasugrel, there was a trend to an improved primary outcome with prasugrel (RR 1.11 (95% CI 0.94 to 1.31)) particularly in those managed with percutaneous coronary intervention (PCI) (RR 1.23 (95% CI 0.95 to 1.59)). Prasugrel demonstrated a statistical superiority with prevention of further MI with RR 1.48 (95% CI 1.11 to 1.97). This was not at the expense of increased major thrombolysis in MI (TIMI) bleeding rates RR 0.94 (95% CI 0.59 to 1.51). CONCLUSIONS: This meta-analysis shows the addition of a P2Y12 inhibitor is superior to placebo, with a trend favouring the use of prasugrel in patients with diabetes with ACS, particularly those undergoing PCI.