Are reciprocal changes a consequence of "ischemia at a distance" or merely a benign electric phenomenon? A PTCA study.

The significance of reciprocal ST-segment depression during acute occlusion of an epicardial coronary artery is still actively debated. "Ischemia at a distance" has been implicated in numerous reports. To determine the prevalence and mechanism of reciprocal changes, we recorded 12-lead electrocardiograms (ECG) during balloon inflation in 66 patients undergoing 79 coronary angioplasty (PTCA) procedures. The 38 men and 28 women had a mean age of 59 +/- 12 years. Twenty nine PTCAs were of the dominant right coronary artery (RCA), 24 were of the proximal left anterior descending artery (LAD), 24 of the left circumflex artery (LCF), and 2 of the diagonal branch of the LAD. Primary ST elevation (> or = 1 mm) occurred in 56 (71%) PTCAs, 49 (88%) of which showed reciprocal (> or = 1 mm) ST depression. Reciprocal changes occurred in 15 of 21, 19 of 20, and 14 of 14 PTCAs of the LAD, RCA, and LCF, respectively (p value not significant [NS]) and were common in patients with collateral vessels supplying the arterial bed distal to the site of balloon occlusion (60%). They were equally prevalent in PTCAs of patients with single-vessel disease and patients with multivessel disease (90% vs 82%, p = NS). We conclude that reciprocal changes occur in the majority regardless of the vessel involved or the extent of coronary artery disease, that they usually represent electric phenomena and not remote ischemia, and that "ischemia at a distance" is not a diagnosis that can be made by ECG.