Increased R-wave amplitude induced by acute myocardial ischemia in the dog: A predictor of malignant ventricular arrhythmias

The ability of an increase of 25 % or greater in the sum of R-wave amplitudes in leads X, Y, Z, L₂, and V₅ to predict the occurrence of malignant ventricular arrhythmias (10 or more ventricular premature beats/min, ventricular tachycardia [5 or more consecutive premature beats], and/or fibrillation) was evaluated in 17 dogs during experimental acute myocardial ischemia. Each dog underwent a 15 minute ligation of the left anterior descending coronary artery followed by reperfusion and after recovery, 2 hours later, a 15 minute ligation of the circumflex coronary artery. During ligation of the left anterior descending coronary artery, 12 of 17 dogs (71%) showed no R-wave increase and no arrhythmias (true-negative response). In 5 (29%) of 17 dogs malignant ventricular arrhythmias developed: 2 of 5 (40%) dogs with arrhythmias had a concomitant R-wave increase (true-positive response), and 3 of 5 (60%) with arrhythmias had a less than 25% increase in R-wave amplitude (false-negative results). During circumflex coronary artery ligation, 13 of 17 (76%) dogs showed both R-wave increases and arrhythmias (true-positive response). Four (24%) of 17 dogs had no arrhythmias: 3 of 4 (75%) with no arrhythmias also had a less than 25% increase in R-wave amplitude (true-negative response), whereas 1 of 4 (25%) dogs with no arrhythmias had an increase in R-wave amplitude (false-positive response). In dogs with both arrhythmias and R-wave increases, R-wave changes preceded the onset of arrhythmias by a mean (± standard deviation) of 1 minute 27 seconds (± 43 seconds). Overall, R-wave increases were highly sensitive (83%), specific (94%), and predictive (94%) for the occurrence of malignant ventricular arrhythmias during experimental acute myocardial ischemia.