Protective effect of pre-infarction angina on microvascular obstruction after primary percutaneous coronary intervention is blunted in humans by cardiovascular risk factors.

BACKGROUND: Pre-infarction angina (PIA) has been shown to reduce the microvascular obstruction (MVO) rate in patients with ST-segment elevation myocardial infarction (STEMI). We sought to evaluate the potential modulator role of cardiovascular risk factors (CRFs) on this protective effect. METHODS AND RESULTS: Two hundred patients with STEMI were enrolled. PIA was defined as typical chest pain within the 48 h preceding STEMI onset. Angiographic MVO was defined as TIMI flow grade <2 or TIMI flow 3 with myocardial blush grade <2; electrocardiographic (ECG) MVO was defined as ST-segment elevation resolution <70%. Common CRFs were collected. In the absence of hypertension, both angiographic and ECG MVO rates were lower in patients with PIA as compared with those without, whereas, in the presence of hypertension, they were similar in both study groups (P for interaction=0.01 and P=0.014, respectively). Among nonsmokers, angiographic and ECG MVO rates were lower in patients with PIA as compared with those without, whereas within smokers, they were similar in both study groups (P for interaction=0.037 and P=0.037, respectively). In the absence of dyslipidemia, the angiographic and ECG MVO rates were lower in patients with PIA as compared with those without, whereas within dyslipidemic patients, they were similar in both study groups (P for interaction=0.012 and P=0.04, respectively). CONCLUSIONS: The protective effect of PIA on MVO is blunted by CRFs.