Correlation of Heart Rate Response during Exercise and Recovery with Severity of Myocardial Ischemia as Judged by Electrocardiographic Findings during Treadmill Testing: Increase in Heart Rate during Recovery Suggest Severe Ischemia with Exercise Induced Left Ventricular Dysfunction

We evaluated eighty one patients complaining of angina or angina equivalent symptoms on effort. Treadmill tests were performed using Bruce protocol. All confounding factors were excluded. Severity of exercise induced myocardial ischemia was decided by clinical and electrocardiographic findings during exercise and recovery. Heart rate response during exercise and recovery was correlated with severity of myocardial ischemia. Chronotropic incompetence had low sensitivity but high specificity in diagnosing severe myocardial ischemia. Decreased magnitude of reduction in heart rate during the first minute of recovery also correlated with severe exercise induced myocardial ischemia. Combining the two parameters increased sensitivity with mild reduction in specificity. Increase, rather than decrease, in heart rate during recovery period strongly correlated with severe myocardial ischemia with possibility of exercise induced left ventricular dysfunction