International Study of Comparative Health Effectiveness with Medical and Invasive Approaches (ISCHEMIA) trial: Rationale and design

Background: Prior trials comparing a strategy of optimal medical therapy with or without revascularization have not shown that revascularization reduces cardiovascular events in patients with stable ischemic heart disease (SIHD). However, those trials only included participants in whom coronary anatomy was known prior to randomization and did not include sufficient numbers of participants with significant ischemia. It remains unknown whether a routine invasive approach offers incremental value over a conservative approach with catheterization reserved for failure of medical therapy in patients with moderate or severe ischemia.

Methods: The ISCHEMIA trial is a National Heart, Lung, and Blood Institute supported trial, designed to compare an initial invasive or conservative treatment strategy for managing SIHD patients with moderate or severe ischemia on stress testing. Five thousand one-hundred seventy-nine participants have been randomized. Key exclusion criteria included estimated glomerular filtration rate (eGFR) <30 mL/min, recent myocardial infarction (MI), left ventricular ejection fraction <35%, left main stenosis >50%, or unacceptable angina at baseline. Most enrolled participants with normal renal function first underwent blinded coronary computed tomography angiography (CCTA) to exclude those with left main coronary artery disease (CAD) and without obstructive CAD. All randomized participants receive secondary prevention that includes lifestyle advice and pharmacologic interventions referred to as optimal medical therapy (OMT). Participants randomized to the invasive strategy underwent routine cardiac catheterization followed by revascularization with percutaneous coronary intervention (PCI) or coronary artery bypass graft (CABG) surgery, when feasible, as selected by the local Heart Team to achieve optimal revascularization. Participants randomized to the conservative strategy undergo cardiac catheterization only for failure of OMT. The primary endpoint is a composite of cardiovascular (CV) death, nonfatal myocardial infarction (MI), hospitalization for unstable angina, hospitalization for heart failure, or resuscitated cardiac arrest. Assuming the primary endpoint will occur in 16% of the conservative group within 4 years, estimated power exceeds 80% to detect an 18.5% reduction in the primary endpoint. Major secondary endpoints include the composite of CV death and nonfatal MI, net clinical benefit (primary and secondary endpoints combined with stroke), angina-related symptoms and disease-specific quality of life, as well as a cost-effectiveness assessment in North American participants. Ancillary studies of patients with advanced chronic kidney disease and those with documented ischemia and non-obstructive coronary artery disease are being conducted concurrently.

Conclusions: ISCHEMIA will provide new scientific evidence regarding whether an invasive management strategy improves clinical outcomes when added to optimal medical therapy in patients with SIHD and moderate or severe ischemia.