Clinical evaluation of coronary lesion characteristics in acute myocardial infarction.

Coronary lesion instability at the onset of acute myocardial infarction (AMI) was evaluated. The mechanism of AMI has been considered to be coronary lesion instability with occlusive thrombus, although more than one half of AMI occurs in clinically stable patients. A total of 313 AMI patients treated by primary percutaneous transluminal coronary angioplasty with provisional stenting (rate, 41%) were studied. They were divided into 2 groups: group 1A (n = 211), without unstable angina before AMI onset, and group 1B (n = 102), with unstable angina before onset. Moreover, angina patients treated similarly were studied: group 2A (n = 180), with stable angina, and group 2B (n = 204), with unstable angina. Coronary lesion instability at AMI onset was also predicted by C-reactive protein (CRP) levels within 6 hours after onset, before they were affected by myocardial damage. The incidence of repeated AMI and/or target vessel revascularization was 1.9% in group 1A, 7.8% in 1B (p=0.035), 1.7% in 2A, and 5.9% in 2B (p=0.043). Event-free survival curves were consistent with each other in groups 1A and 2A and in groups 1B and 2B. CRP levels on admission were 2.0 +/- 1.7 mg/L in group 1A, 3.3 +/- 4.8 mg/L in group 1B (p<0.001), 2.1 +/- 1.7 mg/L in group 2A, and 3.4 +/- 4.7 mg/L in group 2B (p<0.001). Thus coronary lesion characteristics at AMI onset appeared to be similar in groups 1A and 2A and in groups 1B and 2B. A substantial number of patients have stable culprit lesions at the onset of AMI.