International Study of Comparative Health Effectiveness With Medical and Invasive Approaches (ISCHEMIA)

The reflex, when a stress test shows ischemia, is to look — send the patient to the catheterization lab and open the narrowing. ISCHEMIA, one of the largest trials ever run on this question, asked whether that reflex actually helps people with stable disease.

Across 5,179 patients with stable coronary disease and moderate-to-severe ischemia, a routine invasive strategy — angiography with stenting or bypass — was compared against optimal medical therapy alone. At 3.3 years there was no difference in the primary outcome of cardiovascular death, heart attack, cardiac arrest, or hospitalization. Invasive treatment carried a small early harm from the procedures themselves and a small late benefit; over the trial, the two roughly cancelled.

Where the invasive strategy did help was symptoms. Patients with frequent angina felt meaningfully better; the roughly one-third of patients with no angina at baseline gained essentially nothing. Extended follow-up added nuance — cardiovascular death trended lower with invasive treatment, non-cardiovascular death lower with conservative care, and all-cause mortality came out identical.

The practical message cuts against habit. For stable disease, opening a narrowing is largely a treatment for symptoms, not a reliably life-extending one — and an asymptomatic blockage found incidentally rarely needs a stent. That reframing meets resistance, because the cath lab is where much of cardiology’s reflex, and revenue, lives.

The evidence here is strong, and we rate it accordingly: a large, federally funded randomized trial with years of follow-up. The boundaries matter as much as the finding — the results do not apply to acute coronary syndromes, left main disease, very low ejection fraction, or patients whose symptoms aren’t controlled on medication. Within those limits, ISCHEMIA is among the best reasons to ask “will this actually change anything?” before agreeing to a procedure.