Comparison of thrombolytic therapy for acute myocardial infarction in patients aged < 35 and > 55 years.

There are differences in the risk factor profile and coronary anatomy of young patients who develop coronary artery disease compared with those of older ones. There is an absence of data in published reports regarding the response to thrombolytic therapy and the outcome of acute myocardial infarction in young patients. Sixty-two patients aged < 35 years (group 1) were compared with 58 aged > 55 years (group 2) who presented with acute myocardial infarction and were treated with intravenous streptokinase. Group 1 had a significantly higher incidence of smoking (p = 0.0009) and a lower incidence of diabetes mellitus (p = 0.002) than did group 2. Fifty-eight patients in group 1 and 40 in group 2 were studied by angiography at a similar time (5 to 6 days) after admission. Patients in group 1 had a better left ventricular ejection fraction (55 +/- 13% vs 49 +/- 13%; p = 0.03), but similar patency rates of the infarct vessel (74 vs 73%) compared with those of group 2. Group 1 also had a higher incidence of insignificant disease (22.5 vs 2.5%; p = 0.008) and a lower incidence of 3-vessel disease (10 vs 37.5%; p = 0.004). This suggests that there are differences in the risk factor profiles and coronary anatomy of young patients compared with those of older ones. Despite similar benefits from thrombolytic therapy in the form of a patient infarct vessel, there may be differences in the long-term outcome among these patients.