Reperfusion therapy has been effective in reducing mortality in patients who have suffered acute myocardial infarction (MI). However, the risk of mortality is greater in the day after thrombolytic use, which may be the result of reperfusion injury. Adenosine has been shown in animals to reduce the size of myocardial ischemia and improve left ventricular function and coronary blood flow. Only small human studies have reviewed adenosine use in patients with acute MI. Mahaffey and colleagues studied the impact of adenosine therapy in patients with acute MI who receive thrombolytic medications.
The prospective, open-label, placebo-controlled, randomized study was conducted at 19 sites. Patients with acute MI who presented within six hours of the onset of chest pain and were to receive thrombolytic therapy were considered for the trial. They were randomly assigned to receive intravenous adenosine or placebo. Outcomes measured were myocardial infarct size, myocardial salvage index, reinfarction, congestive heart failure, cardiogenic shock, stroke or death.
A total of 236 patients was enrolled in the study. A 33 percent reduction in infarction size was seen in the adenosine treatment group compared with the placebo group. The reduction was 67 percent if the infarction was anterior in location. The clinical outcomes for the adenosine-treated group tended to be slightly worse than those in the placebo group, but statistical significance was not achieved.
The authors conclude that adenosine as an adjuvant to thrombolytic therapy in patients with acute MI can reduce the infarction size. However, a larger clinical outcome trial should be performed before adenosine is used with thrombolytics in patients with acute MI.