Objectives: Advancing age is an independent predictor of increased mortality after acute myocardial infarction (AMI). Several hypotheses have been developed to try to explain this phenomenon, but data available about the efficacy of thrombolytic therapy in older patients are still not conclusive. The goal of this study was to investigate the efficacy of thrombolysis in adult and older patients who suffered their first AMI.
Design: Retrospective cohort study.
Setting: A coronary care unit.
Participants: The sample included 244 younger (aged <65, n = 166) and older (age 65, n = 78) adult patients suffering their first Q-wave AMI, all receiving thrombolysis with human-recombinant tissue-type plasmin-ogen activator (100 mg total dose within 2.5 hours of the onset of AMI.
Measurements: Infarct size was estimated by isoenzyme creatine kinase-myoglobin (CK-MB) release, measuring the area under the curve as a function of time. ST elevation, the sum of ST elevation above the baseline, and the sum of R wave height in precordial leads V1-V6 were evaluated using 12-lead electrocardiograms. Myocardial reperfusion was calculated when ST-segment elevation decreased more than 60 with respect to the most abnormal peak detected.
Results: CK-MB peak level was significantly smaller in younger patients than in older ones (P< .01) and was significantly correlated with increasing age (P< .0001). Area under the 36-hour CK-MB curve was lower in younger patients than in older ones (P< .0001) and was well correlated with increasing age (P< .01). Reperfusion time was significantly shorter in younger patients (P< .05), and age was significantly correlated with reperfusion time (P< .001).
Conclusions: Infarct size was greater and reperfusion time was longer in older patients than in younger ones with first Q-wave AMI treated with thrombolysis. Infarct size and reperfusion time were linearly correlated with increasing age. These findings may help explain the increase in mortality due to AMI observed with advancing age.