Clinical Heart and Vascular Center
ISCHEMIA Trial Provides Evidence for Less Use of Invasive Therapies in SIHD Patients
I had the privilege of serving as a moderator, and having a front-row seat, for the presentation of the International Study of Comparative Health Effectiveness with Medical and Invasive Approaches (ISCHEMIA) trial. This landmark trial, sponsored by the NHLBI/NIH, asked a clinical question relevant to all of us practicing cardiology: “In stable patients with at least moderate ischemia on a stress test, is there a benefit to adding cardiac catheterization and, if feasible, revascularization to optimal medical therapy?”
The trial was extremely well done, enrolling patients with substantial ischemia on noninvasive testing and maintaining strict adherence to the protocol, such that the difference in revascularization between the invasive and conservative arms was very large (79% vs 12% at one month). The primary outcome of CV death, MI, hospitalization for unstable angina, heart failure, or resuscitated cardiac arrest was not different between the groups after an average 3.3 years of follow-up (HR 0.93, 95% CI [0.80, 1.08]). While there did appear to be a small benefit in reduction of myocardial infarction in the invasive arm, there were no benefits on mortality or stroke. No subgroups were found where invasive therapy was superior for the primary endpoint. In contrast, quality of life, as assessed with the Seattle Angina Questionnaire, was modestly better in the invasive arm, with the proportion of individuals reporting complete freedom from angina also being higher.
"This landmark trial, sponsored by the NHLBI/NIH, asked a clinical question relevant to all of us practicing cardiology: ‘In stable patients with at least moderate ischemia on a stress test, is there a benefit to adding cardiac catheterization and, if feasible, revascularization to optimal medical therapy?'"
The authors concluded, rightly in my view, that in patients without severe left main coronary disease (who were excluded based on pre-enrollment coronary CTA) or severe left ventricular dysfunction (also excluded), invasive therapy does not improve hard clinical outcomes in patients with stable ischemic heart disease but does result in improvements in angina frequency. These findings, while not altogether surprising, have broad implications because they support less use of invasive therapies in patients with stable ischemic heart disease, and probably less noninvasive testing for ischemia.
Because revascularization for ischemia in stable patients does not improve clinical outcomes, there is probably less need for ischemia testing. For patients with substantial angina burden, an individualized discussion about goals of care should be used to determine who should be referred for invasive management. Longer-term follow-up of the ISCHEMIA patients will be critical to make sure that differences between groups do not emerge over time.