Determinants of myocardial ischemia during percutaneous transluminal coronary angioplasty in patients with significant narrowing of a single coronary artery and stable or unstable angina pectoris.

Previous studies have assessed the determinants of collateral vessel recruitment during coronary occlusion in patients undergoing percutaneous transluminal coronary angioplasty (PTCA). However, the determinants of severity of myocardial ischemia after sudden coronary occlusion do not necessarily coincide with those responsible for collateral vessel recruitment. The aim of this study was to assess the determinants of severity of myocardial ischemia during balloon inflation by recording surface and intra-coronary electrocardiograms (ECGs). In 62 consecutive patients with 1-vessel disease and without previous myocardial infarction undergoing successful PTCA for stable (n = 33) or unstable (n = 29) angina pectoris, the summation of the absolute values of ST-segment shifts from baseline on the intracoronary and surface ECG at the end of the first 2-minute inflation was obtained as an index of the severity of myocardial ischemia. Stenosis severity before PTCA was measured using computerized coronary angiography, while the grade of collateral filling was scored according to Rentrop's classification. The mean (+/- 1 SD) ST-segment shift at the end of balloon inflation was less in patients with than without collateral vessels (12 +/- 10 vs 23 +/- 15 mm, p < 0.05). Despite a similar prevalence of collateral vessels (34% vs 24%, p = NS), the mean ST-segment shift was also less in patients with unstable than stable angina (15 +/- 9 vs 24 +/- 17 mm, p < 0.05). However, the mean ST-segment shift was not associated with the severity of coronary stenosis before PTCA (r = 0.0004, p = NS).(ABSTRACT TRUNCATED AT 250 WORDS)