ISCHEMIA trial: Is there enough evidence to drive a change in clinical practice? A critical appraisal

Area of Science:

• Cardiology
• Clinical Trials
• Interventional Cardiology

Background:

• The ISCHEMIA trial investigated the efficacy of an invasive strategy (cardiac catheterization and revascularization) versus a conservative strategy in patients with stable coronary artery disease (CAD) and moderate to severe ischemia.
• The study aimed to determine if an invasive approach reduces major adverse cardiovascular events compared to optimal medical therapy alone.

Discussion:

• The trial reported no significant difference in the primary composite outcome (cardiovascular death, MI, or hospitalization for unstable angina, heart failure, or resuscitated cardiac arrest) between invasive and conservative strategies over a median follow-up of 3.2 years.
• Patients undergoing the invasive strategy experienced more procedural myocardial infarctions (MIs) but fewer spontaneous MIs during follow-up.
• Study limitations included implementation challenges, low event rates, compromised statistical power, and evolving endpoint definitions, leading to a "heterobaric" combined endpoint.

Key Insights:

• An initial invasive strategy did not reduce the composite rates of death, MI, or specific hospitalizations compared to an initial conservative strategy in stable CAD patients with moderate to severe ischemia.
• The balance of procedural versus spontaneous MIs differed between groups, with procedural MIs favoring the conservative arm and spontaneous MIs favoring the invasive arm.
• Low overall mortality and similar rates between groups suggest caution in interpreting definitive benefits of early revascularization in this population.

Outlook:

• Given the study's limitations and the heterogeneity of stable CAD patients, it is premature to alter current clinical practice based solely on ISCHEMIA trial results.
• Individualized patient assessment and shared decision-making, guided by existing clinical guidelines, are recommended before implementing changes in management strategies for stable CAD.
• Further research may be needed to clarify the long-term impact of invasive versus conservative strategies, particularly considering evolving definitions and patient subgroups.