The effect of preinfarction angina on clinical reperfusion time in patients with acute myocardial infarction receiving successful thrombolytic therapy

BACKGROUND: Preinfarction angina (PA) and early reperfusion of infarct-related arteries have been shown to reduce infarct size in patients with acute myocardial infarction (AMI). The beneficial effects of PA on infarct size have been attributed to the development of ischemic preconditioning and faster coronary recanalization in patients treated with thrombolytic therapy (TT). OBJECTIVE: To evaluate the effect of PA on clinical coronary reperfusion time in patients with AMI receiving successful TT. METHODS: Seventy-five patients presenting with AMI (within 6 h after the initial onset of symptoms) were studied. All patients received TT and were evaluated with coronary angiography (CA) at predischarge. The patients were divided into two groups: group 1 (PA-positive) comprised those who experienced a new onset of prodromal angina within 72 h before the onset of AMI. Group 2 (PA-negative) comprised those who had a sudden onset of AMI without the preceding angina. The successful myocardial reperfusion criteria after TT were ST segment resolution of 50% or greater, the appearance of reperfusion arrhythmias and the resolution of chest pain. The time of reperfusion criteria was recorded after TT. CA was performed in all patients at predischarge. Patients with no patent infarct-related arteries on CA and clinical failure of reperfusion were excluded from the study. RESULTS: Clinical characteristics, risk factors and angiographic findings did not differ significantly between the groups. The time interval from the start of continuous chest pain to TT was also similar between the groups. The left ventricular ejection fraction was higher and there were less frequent ventricular arrhythmias in patients with PA than in those without PA (47.9+/-7.4 versus 44.4+/-8.1, P=0.041, and 17.1% versus 37.5%, P=0.043, respectively). The clinical reperfusion time was significantly shorter in the patients with PA than in those without PA (68.2+/-24.5 min versus 81.4+/-19.3, P=0.012). The clinical reperfusion time was positively correlated with age and the time interval from the start of continuous chest pain to TT but inversely related to the presence of PA. CONCLUSIONS: In patients with AMI preceded by PA, TT resulted in more rapid clinical reperfusion than in patients without PA. Thus, earlier myocardial reperfusion may account for smaller infarct size and better prognosis in patients with PA.