Preinfarction angina limits myocardial infarction size in nondiabetic patients treated with primary coronary angioplasty.

OBJECTIVE To evaluate myocardial necrosis extent after myocardial infarction (MI) and reperfusion with primary coronary angioplasty in nondiabetic patients and the relationship with unstable preinfarction angina (PA). DESIGN Prospective cohort study. SETTING Studies suggest PA limits infarct size. This effect is questioned in patients treated with primary coronary angioplasty. PATIENTS Seventy-eight, nondiabetic, consecutive MI patients. INTERVENTIONS Primary coronary angioplasty and scintigraphic study to assess the myocardial infarct size. MAIN OUTCOME MEASURES Scintigraphic myocardial infarct size. RESULTS There were 32 patients with PA (PA +) and 46 without PA (PA -) in the 24-h period prior to MI onset. There were no significant differences in the baseline characteristics between the two groups. The scintigraphy indicated myocardial infarct size significantly smaller in PA + patients: mean, 18.0% (SD, 14.7) vs 27.0% (SD, 20.1) [p = 0.033]. This occurs even though Thrombolysis in Myocardial Infarction grade 3 flow achieved in both groups was similar (84.8% vs 84.4%, p = 1.000). We found a higher percentage of ST-segment resolution (>/= 70%) in PA + patients (65.6% vs 45.7%, p = 0.082) together with a lower incidence of left ventricular systolic dysfunction (3.2% vs 18.6%, p = 0.071). CONCLUSIONS PA exerts a beneficial effect in nondiabetic patients with ST-segment elevation acute MI even when treated with primary PCI. The infarct size is limited, and left ventricular systolic function is preserved. The effects may be related to a better preservation of tissue reperfusion in patients with PA.