Stephen P. Hoole

Spontaneous coronary artery dissection (SCAD) has long been recognized as a cause of acute coronary syndromes (ACS). Initially considered very rare and associated primarily with pregnancy and the peripartum period, the use of higher sensitivity Troponin assays and early angiography in ACS, coupled with greater awareness of the condition, has led to increased diagnosis, and it is now understood that SCAD represents a significant cause of ACS in predominantly young to middleaged women, with most cases occurring outside the context of recent pregnancy.1,2 Although there are no randomized controlled trials in SCAD, knowledge has further advanced in the last 5-years as a result of an international research effort primarily focused on building and studying national SCAD registries.3–19 These studies have demonstrated, not only that SCAD is a distinct pathophysiological entity, but that there are key differences in management and outcomes compared to ACS of atherosclerotic aetiology. This position paper aims to set-out current knowledge on SCAD for the benefit of practicing clinicians caring for patients with this condition. It presents the consensus on contemporary management and areas of controversy and uncertainty, which remain a focus of ongoing research. The information is provided to support clinical care providers but is not intended to replace individualized decision-making by clinicians and other health care professionals. [...]

BACKGROUND: Myocyte necrosis as a result of elective percutaneous coronary intervention (PCI) occurs in approximately one third of cases and is associated with subsequent cardiovascular events. This study assessed the ability of remote ischemic preconditioning (IPC) to attenuate cardiac troponin I (cTnI) release after elective PCI. METHODS AND RESULTS: Two hundred forty-two consecutive patients undergoing elective PCI with undetectable preprocedural cTnI were recruited. Subjects were randomized to receive remote IPC (induced by three 5-minute inflations of a blood pressure cuff to 200 mm Hg around the upper arm, followed by 5-minute intervals of reperfusion) or control (an uninflated cuff around the arm) before arrival in the catheter laboratory. The primary outcome was cTnI at 24 hours after PCI. Secondary outcomes included renal dysfunction and major adverse cardiac and cerebral event rate at 6 months. The median cTnI at 24 hours after PCI was lower in the remote IPC compared with the control group (0.06 versus 0.16 ng/mL; P=0.040). After remote IPC, cTnI was <0.04 ng/mL in 44 patients (42%) compared with 24 in the control group (24%; P=0.01). Subjects who received remote IPC experienced less chest discomfort (P=0.0006) and ECG ST-segment deviation (P=0.005) than control subjects. At 6 months, the major adverse cardiac and cerebral event rate was lower in the remote IPC group (4 versus 13 events; P=0.018). CONCLUSIONS: Remote IPC reduces ischemic chest discomfort during PCI, attenuates procedure-related cTnI release, and appears to reduce subsequent cardiovascular events.

AIMS: This meta-analysis aims to quantify the association of reduced coronary flow with all-cause mortality and major adverse cardiovascular events (MACE) across a broad range of patient groups and pathologies. METHODS AND RESULTS: We systematically identified all studies between 1 January 2000 and 1 August 2020, where coronary flow was measured and clinical outcomes were reported. The endpoints were all-cause mortality and MACE. Estimates of effect were calculated from published hazard ratios (HRs) using a random-effects model. Seventy-nine studies with a total of 59 740 subjects were included. Abnormal coronary flow reserve (CFR) was associated with a higher incidence of all-cause mortality [HR: 3.78, 95% confidence interval (CI): 2.39-5.97] and a higher incidence of MACE (HR 3.42, 95% CI: 2.92-3.99). Each 0.1 unit reduction in CFR was associated with a proportional increase in mortality (per 0.1 CFR unit HR: 1.16, 95% CI: 1.04-1.29) and MACE (per 0.1 CFR unit HR: 1.08, 95% CI: 1.04-1.11). In patients with isolated coronary microvascular dysfunction, an abnormal CFR was associated with a higher incidence of mortality (HR: 5.44, 95% CI: 3.78-7.83) and MACE (HR: 3.56, 95% CI: 2.14-5.90). Abnormal CFR was also associated with a higher incidence of MACE in patients with acute coronary syndromes (HR: 3.76, 95% CI: 2.35-6.00), heart failure (HR: 6.38, 95% CI: 1.95-20.90), heart transplant (HR: 3.32, 95% CI: 2.34-4.71), and diabetes mellitus (HR: 7.47, 95% CI: 3.37-16.55). CONCLUSION: Reduced coronary flow is strongly associated with increased risk of all-cause mortality and MACE across a wide range of pathological processes. This finding supports recent recommendations that coronary flow should be measured more routinely in clinical practice, to target aggressive vascular risk modification for individuals at higher risk.

BACKGROUND: In patients with acute myocardial infarction (MI), therapies that could further reduce the risk of adverse cardiovascular and metabolic outcomes are needed. METHODS: In this international registry-based, randomized, double-blind trial, patients without prior diabetes or chronic heart failure, presenting with acute MI and impaired left ventricular systolic function, were randomly assigned 10 mg of dapagliflozin or placebo, given once daily. The primary outcome was the hierarchical composite of death, hospitalization for heart failure, nonfatal MI, atrial fibrillation/flutter, type 2 diabetes mellitus, New York Heart Association Functional Classification at the last visit, and body weight decrease of 5% or greater at the last visit using the win ratio analysis method. The key secondary outcome was the same hierarchical composite excluding the body weight component. RESULTS: We enrolled 4017 patients of whom 2019 were assigned to dapagliflozin and 1998 to placebo. The analysis of the primary hierarchical composite outcome resulted in significantly more wins for dapagliflozin than for placebo (win ratio, 1.34; 95% confidence interval [CI], 1.20 to 1.50; P<0.001). The win ratio outcome, which was adopted in a change of analysis during trial performance because of low event accrual, was mainly driven by the added cardiometabolic outcomes. The composite of time to cardiovascular death/hospitalization for heart failure occurred in 50/2019 (2.5%) patients assigned to dapagliflozin and 52/1998 (2.6%) patients assigned to placebo (hazard ratio, 0.95; 95% CI, 0.64 to 1.40). The rates of other cardiovascular events were low, with differences between the groups not reaching nominal statistical significance. No safety concerns were identified. CONCLUSIONS: In patients with acute MI as noted above, after approximately 1 year of treatment with dapagliflozin there were significant benefits with regard to improvement in cardiometabolic outcomes but no impact on the composite of cardiovascular death or hospitalization for heart failure compared with placebo. (Funded by AstraZeneca; ClinicalTrial.gov number, NCT04564742.)