[Thrombolysis in the elderly with acute myocardial infarction. The PRIAMHO study]

In the elderly with acute myocardial infarction the risks and benefits of thrombolytic therapy are not well defined due mainly to the lack of randomized trials. In the present study we examined the clinical profile of the aged treated with thrombolytic agents and the effects of that therapy on 28 day and 1 year mortality.

We studied 733 patients aged > 75 years (mean: 79.9) admitted to the Coronary Care Unit (CCU) of 24 Spanish hospitals with a confirmed diagnosis of Q-Wave myocardial infarction (MI). On admission, 293 patients were treated with thrombolytics and 440 patients received standard therapy. The difference between the two groups in the clinical profile of MI, treatments administered in CCU, evolutive course and 28 day and 1 year mortality were assessed.

The independent predictors related to the use of thrombolytic therapy were age (OR: 0.93; 95% CI: 0.89-0.97), history of arterial hypertension (OR: 0.85; 95% CI: 0.71-1.01), delay time to admission (OR: 0.998; 95% CI: 0.997-0.999), anterior location of infarct (OR: 1.21; 95% CI: 1.01-1.24) and Killip Class III-IV (OR: 0.79; 95% CI: 0.64-0.97). During the evolution thrombolysis therapy was associated with lower rates of Killip III-IV (p < 0.00001), complete AV block (p = 0.037), intraventricular conduction defects (p = 0.046) and a higher incidence of stroke (p < 0.01). The 28-day mortality was also significantly lower in the group receiving thrombolytics (27 vs 31. 3%; p = 0.035). However, this difference disappeared when the analysis was adjusted with other variables such as age, administration of aspirin and Killip Class III-IV (OR: 1.29; 95% IC: 0.87-1.92).

The results of this trial suggest that in the elderly with acute myocardial infarction thrombolysis is associated with a less complicated evolutive course and a lower 28-day mortality. However, these findings could be mediated by other covariables such as age, more frequent use of aspirin and a higher number of patients with Killip Class III-IV excluded from the thrombolytic therapy.