Influences of electrocardiographic ischaemia grades and symptom duration on outcomes in patients with acute myocardial infarction treated with thrombolysis versus primary percutaneous coronary intervention: Results from the DANAMI-2 trial

Objective: To determine whether ischaemia grade (GI) on the presenting ECG and duration of symptoms can identify subgroups of patients who would derive more benefit than the general population of patients with ST segment elevation acute myocardium infarction (STEMI) from primary percutaneous coronary intervention (pPCI) over thrombolytic treatment (TT) in reducing mortality or reinfarction. Methods: 1319 DANAMI-2 (Danish trial in Acute Myocardial Infarction-2) patients were classified as having grade 2 ischaemia (GI2; ST segment elevation without terminal QRS distortion) or grade 3 ischaemia (GI3; ST segment elevation with terminal QRS distortion in ≥ 2 adjacent leads), and were divided into early and late groups split by the median time (3 h) from symptom onset to treatment. Outcomes were 30-day mortality and reinfarction. Results: Mortality was significantly higher for GI3 than for GI2 (9.7% v 4.8%, p < 0.001) and doubled for patients presenting late (GI2: 6.0% v 3.3%, p = 0.01; GI3: 12.5% v 4.7%, p = 0.05). Overall mortality did not differ significantly between pPCI and TT; however, a 5.5% absolute mortality reduction was seen in GI3 treated early with pPCI (1.4% v 6.9%, p = 0.10). Reinfarction rate was particularly high among GI3 patients presenting late and treated with TT (12.2%). pPCI in such patients significantly reduced the rate of reinfarction (0%, p < 0.001 ). Logistic regression analysis showed that age (odds ratio (OR) 1.09, 95% confidence interval (CI) 1.06 to 1.12, p < 0.001), prior angina (OR 2.56, 95% CI 1.44 to 4.54, p = 0.001 ), heart rate (OR 1.03, 95% CI 1.01 to 1.04, p = 0.001 ) and GI3 (OR 1.91, 95% CI 1.06 to 3.44, p = 0.031) were independently associated with mortality, whereas the sum of ST segment elevation was not. Conclusions: GI3 is an independent predictor of mortality among patients with STEMI. Mortality increased significantly with symptom duration in both GI2 and GI3. pPCI may be especially beneficial for patients with GI3 presenting early, whereas patients with GI3 presenting late and treated with TT are at particular risk of reinfarction.