Predictive factors and impact of no reflow after primary percutaneous coronary intervention in patients with acute myocardial infarction.

BACKGROUND The investigation of no-reflow phenomenon after percutaneous coronary intervention (PCI) in patients with acute ST-segment-elevation myocardial infarction has therapeutic implications. We investigated the predictive factors, persistence in time, and impact of no reflow on myocardial salvage, ventricular function, and mortality. METHODS AND RESULTS The study included 1140 patients with ST-segment-elevation myocardial infarction undergoing primary PCI and paired scintigraphic examinations (before intervention and 7 to 14 days thereafter). After primary PCI, 108 patients had no reflow and 1032 patients had normal coronary flow. The median salvage index was 0.34 (interquartile range, 0.15, 0.49) in patients with no reflow versus 0.55 (interquartile range, 0.29, 0.81) in patients with normal flow (P<0.001). Left ventricular ejection fraction at 6 months after PCI was 47.7+/-13.1% in the no-reflow group versus 54.2+/-13.9% in the group with normal flow after PCI (P<0.001). In 80.3% of patients with no reflow, normalization of blood flow >6 months after PCI occurred and correlated with improvement in the left ventricular ejection fraction. Independent predictors of no reflow were residual flow in the infarct-related artery (P<0.001), initial perfusion defect (P=0.03), C-reactive protein (P<0.001), and previous myocardial infarction (P=0.013). Kaplan-Meier estimates of 1-year mortality were 16.7% (n=18) in patients with no reflow versus 5.5% (n=56) in patients with normal flow (hazard ratio, 3.35; 95% CI, 1.97 to 5.69; P<0.001). CONCLUSIONS No reflow after primary PCI was associated with reduced myocardial salvage, larger infarct size, worse left ventricular ejection fraction at 6 months, and increased risk of 1-year mortality. In 4 of 5 patients with no reflow after PCI, restoration of normal flow occurred 6 months after reperfusion.