Predictors and outcome of grade 3 ischemia in patients with ST-segment elevation myocardial infarction undergoing primary percutaneous coronary intervention

Grade 3 ischemia (G3I: distortion of the terminal portion of the QRS complex) is a predictor of serious complications after acute myocardial infarction. However, less is known about which patients are more prone to present with G3I. Patients who were enrolled in the Ongoing Tirofiban In Myocardial infarction Evaluation trial 2 were included. These patients were divided in 2 groups based on the enrolment electrocardiogram: grade 2 ischemia (G2I) or G3I. Between June 2004 and November 2007, 1308 patients with interpretable electrocardiograms were enrolled. Grade 3 ischemia was found in 426 (32.6%) patients. Patients with G3I were older, more often male, more often had diabetes, had a Thrombolysis In Myocardial Infarction (TIMI) risk score of greater than 3, had 3 vessel disease, had an anterior infarction, more often presented in Killip class greater than 1, less often had a preprocedural TIMI 3 flow, and less often had a myocardial blush grade 3 post-PCI. One hour post-PCI, residual ST deviation was higher in patients with G3I compared with patients with G2I. Furthermore, G3I was associated with more major cardiac events (including death, myocardial infarction, urgent target vessel revascularization). After multivariate adjustment, G3I was an independent predictor of failure of ST-segment resolution 1 hour post-PCI (odds ratio, 1.4; 95% confidence interval, 1.1-1.9) and 30-day mortality (odds ratio, 3.2; 95% confidence interval, 1.2-8.7). Grade 3 ischemia was associated with high-risk patient criteria (older age, diabetes, TIMI risk score >3, Killip class >1, and anterior myocardial infarction) and represents a subgroup of high-risk patients who seems to be associated with poor myocardial reperfusion and worse outcome.