Ischemic preconditioning (IP) has been shown to reduce the infarct size and severity of arrhythmia in a post-ischemic reperfused heart. Angina before myocardial infarction reflects brief episodes of myocardial ischemia and may be a marker of ischemic preconditioning. We studied the effect of a history of previous angina on early outcomes (infarct size, left ventricular (LV) function and residual myocardial ischemia) for patients with acute myocardial infarction (AMI) after thrombolytic therapy.

We examined prospectively 58 consecutive patients who had AMI and arrived hospital within 6 hours after chest pain developed. IP was defined as prodromal angina within 24 hours before myocardial infarction. Patients were divided 2 groups:Group I (Gr I, 30 cases) without IP, Group II (Gr II, 28 cases) with IP. Thrombolytic therapy was done 23 cases (77%) and 21 cases (75%) respectively in each groups. Thereafter, electrocardiographic findings, infarct size on the basis of peak creatine kinase, LV function on the 2-D echocardiographic findings, recurrent myocardial ischemia were examined between 2 groups.

In predischarge 2-D echocardio-graphic findings, LV dilatation and normal regional wall motion did not differ between two groups. But, there were significantly smaller creatine kinase (CK)-determined infarct size in Gr II than that in Gr I (peak CK level, Gr I:1566.3±960.0 IU/L vs Gr II:1066.9±773.2; p<0.05). The time interval between the onset of infarction and peak CK level was shorter in Gr II than that in Gr I (Gr I:18.3±8.3 vs Gr II:10.7±3.4 hours; p<0.001). There were significantly more common incidences of residual myocardial ischemia in Gr II (Gr I:26.7% vs Gr II:60.7%; p<0.01).

Patients with a history of prodromal angina preceding myocardial infarction had small infarct size and earlier reperfusion of infarct related artery. However, there were significantly more common residual myocardial ischemia in these patients and a trend toward re-infarction on same previous infarction sites.