Thrombolytic therapy is the coronary artery reperfusion method most commonly used in patients with acute ST-segment elevation myocardial infarction (STEMI). It is unknown whether immediate mechanical reperfusion (IMR) improves outcomes in patients with STEMI who have contraindications to thrombolytic reperfusion therapy. In this study, Grzybowski and colleagues investigated whether IMR provides a mortality benefit in patients with STEMI who are ineligible for thrombolysis.
The study included patients from the National Registry of Myocardial Infarction. Participants were eligible if they had electrocardiographic changes that made them candidates for thrombolytic therapy (defined as STEMI or presumed new left bundle branch block), if they had symptom onset within the previous 12 hours, and if they had contraindications to thrombolytic therapy. Eligible patients were divided into two groups: those who did and those who did not receive IMR (defined as percutaneous coronary intervention or coronary bypass graft surgery within 12 hours of symptom onset). Because this assignment was not random, the authors made statistical adjustments to account for potentially confounding factors and selection biases.
Of the 19,917 patients who were eligible for the study, 4,705 (23.6 percent) received IMR. Overall, 5,173 patients (25.9 percent) died in the hospital. The use of IMR was statistically significantly associated with reduced mortality in all unadjusted and adjusted analyses. All statistical models were consistent with this finding except for one, which categorized patients by quintile and showed no mortality difference in the first quintile.
In this study, patients with acute STEMI and contraindications to thrombolytic therapy had reductions in mortality associated with IMR treatment of 63.7 and 45.8 percent, depending on the statistical model. Because only 23.6 percent of eligible patients received IMR, the authors suggest that increased use of IMR treatment potentially could reduce mortality in patients with contraindications to thrombolytic therapy; however, such intervention likely would require prehospital diversion of eligible patients to IMR-capable facilities. This study did not identify subgroups of eligible patients who were most likely to benefit from IMR treatment.