PPCI Shows a Significant Mortality Benefit in High-Risk Patients Only

As a reperfusion strategy, thrombolysis has been shown to have similar benefit with regard to mortality as primary percutaneous coronary intervention (PPCI) in patients with ST-segment elevation myocardial infarction (STEMI) who are not considered high risk, according to results of a recent study [Arch Intern Med. 2011;171(6):544-549]. PPCI remains the recommended reperfusion treatment for patients with STEMI if it can be performed promptly. Thrombolysis in Myocardial Infarction (TIMI), a scoring system that measures a patient’s risk of short-term mortality, is based on clinical data that can be obtained upon admission, such as age, Killip class, and blood pressure. Whether TIMI can be used to help determine which high-risk patients may benefit most from PPCI is not clear. Marc J. Claeys, MD, PhD, of University Hospital Antwerp, Edegem, Belgium, and his colleagues sought to evaluate the mortality differences between PPCI and thrombolysis among an unselected community-based population. The researchers obtained data from a prospective observational database that contained demographics, practice patterns, and health outcomes of unselected patients with STEMI from July 2007 through December 2009. All patients had ST elevation or presumed new left bundle branch block and received reperfusion therapy within 12 hours of symptom onset. Patients were considered low risk if their TIMI score was 0 to 2, intermediate risk at 3 to 6, and high risk at 7 to 14. The primary end point was in-hospital death from all causes by day 0 after admission. There were 721 patients who underwent thrombolysis and 4574 patients who underwent PPCI. Of the entire study population of 5295, 1934 (36.5%) had a low TIMI score, 2382 (45%) had an intermediate TIMI score, and 979 (18.5%) were considered high TIMI risk. Overall TIMI risk scores were found to be slightly lower for thrombolysis patients compared with PPCI patients (3.8 vs 4.1). The researchers used multiple logistic regression in their analysis. Results showed a total in-hospital mortality of 6.0%; the median length of time to death was 2 days after admission. Total mortality was 6.6% for thrombolysis patients and 5.9% for PPCI patients (unadjusted P=.40). There was nearly a 30-fold increase in risk between patients who had a TIMI risk score of 0 and patients who had a score of ≥8. The researchers found the absolute mortality benefit for high-risk patients to be 7.1% (30.6% for thrombolysis patients compared with 23.7% for PPCI patients; adjusted P=.03). For the intermediate- and low-risk patients, the absolute mortality difference was slight (0.2% for intermediate risk; 3.1% for thrombolysis and 2.9% for PPCI, adjusted P=.30; and 0.1% for low risk; 0.4% for thrombolysis and 0.3% for PPCI, adjusted P=.60). Results also showed the most important independent risk factors associated with in-hospital death were age, Killip class >1, low blood pressure, cardiopulmonary resuscitation, history of peripheral arterial disease, longer treatment delay, anterior infarction location, and being a woman. Treatment strategy was an important independent predictor that favored PPCI for high-risk patients, with an odds ratio of 0.54. No significant difference between PPCI and thrombolysis was found among low- and intermediate-risk patients. The researchers also found that to maintain the lowest mortality rates, the ideal time to perform PPCI was <60 minutes from diagnosis of STEMI. The researchers acknowledged the focus on short-term mortality was a study limitation, as was the possibility of underreporting, which may have created a selection bias.