In patients who have acute myocardial infarction with cardiogenic shock, early revascularization of the culprit artery by means of percutaneous coronary intervention (PCI) improves outcomes. However, the majority of patients with cardiogenic shock have multivessel disease, and whether PCI should be performed immediately for stenoses in nonculprit arteries is controversial.

Coronary revascularization guided by fractional flow reserve (FFR) is associated with better patient outcomes after the procedure than revascularization guided by angiography alone. It is unknown whether the instantaneous wave-free ratio (iFR), an alternative measure that does not require the administration of adenosine, will offer benefits similar to those of FFR. We randomly assigned 2492 patients with coronary artery disease, in a 1:1 ratio, to undergo either iFR-guided or FFR-guided coronary revascularization. The primary end point was the 1-year risk of major adverse cardiac events, which were a composite of death from any cause, nonfatal myocardial infarction, or unplanned revascularization. The trial was designed to show the noninferiority of iFR to FFR, with a margin of 3.4 percentage points for the difference in risk. At 1 year, the primary end point had occurred in 78 of 1148 patients (6.8%) in the iFR group and in 83 of 1182 patients (7.0%) in the FFR group (difference in risk, −0.2 percentage points; 95% confidence interval [CI], −2.3 to 1.8; P<0.001 for noninferiority; hazard ratio, 0.95; 95% CI, 0.68 to 1.33; P=0.78). The risk of each component of the primary end point and of death from cardiovascular or noncardiovascular causes did not differ significantly between the groups. The number of patients who had adverse procedural symptoms and clinical signs was significantly lower in the iFR group than in the FFR group (39 patients [3.1%] vs. 385 patients [30.8%], P<0.001), and the median procedural time was significantly shorter (40.5 minutes vs. 45.0 minutes, P=0.001). Coronary revascularization guided by iFR was noninferior to revascularization guided by FFR with respect to the risk of major adverse cardiac events at 1 year. The rate of adverse procedural signs and symptoms was lower and the procedural time was shorter with iFR than with FFR. (Funded by Philips Volcano; DEFINE-FLAIR ClinicalTrials.gov number, NCT02053038.)

Among patients with acute myocardial infarction, cardiogenic shock, and multivessel coronary artery disease, the risk of a composite of death from any cause or severe renal failure leading to renal-replacement therapy at 30 days was found to be lower with percutaneous coronary intervention (PCI) of the culprit lesion only than with immediate multivessel PCI. We evaluated clinical outcomes at 1 year. We randomly assigned 706 patients to either culprit-lesion-only PCI or immediate multivessel PCI. The results for the primary end point of death or renal-replacement therapy at 30 days have been reported previously. Prespecified secondary end points at 1 year included death from any cause, recurrent myocardial infarction, repeat revascularization, rehospitalization for congestive heart failure, the composite of death or recurrent infarction, and the composite of death, recurrent infarction, or rehospitalization for heart failure. As reported previously, at 30 days, the primary end point had occurred in 45.9% of the patients in the culprit-lesion-only PCI group and in 55.4% in the multivessel PCI group (P=0.01). At 1 year, death had occurred in 172 of 344 patients (50.0%) in the culprit-lesion-only PCI group and in 194 of 341 patients (56.9%) in the multivessel PCI group (relative risk, 0.88; 95% confidence interval [CI], 0.76 to 1.01). The rate of recurrent infarction was 1.7% with culprit-lesion-only PCI and 2.1% with multivessel PCI (relative risk, 0.85; 95% CI, 0.29 to 2.50), and the rate of a composite of death or recurrent infarction was 50.9% and 58.4%, respectively (relative risk, 0.87; 95% CI, 0.76 to 1.00). Repeat revascularization occurred more frequently with culprit-lesion-only PCI than with multivessel PCI (in 32.3% of the patients vs. 9.4%; relative risk, 3.44; 95% CI, 2.39 to 4.95), as did rehospitalization for heart failure (5.2% vs. 1.2%; relative risk, 4.46; 95% CI, 1.53 to 13.04). Among patients with acute myocardial infarction and cardiogenic shock, the risk of death or renal-replacement therapy at 30 days was lower with culprit-lesion-only PCI than with immediate multivessel PCI, and mortality did not differ significantly between the two groups at 1 year of follow-up. (Funded by the European Union Seventh Framework Program and others; CULPRIT-SHOCK ClinicalTrials.gov number, NCT01927549.)