Recovery-phase patterns of ST segment depression in the heart rate domain. Identification of coronary artery disease by the rate-recovery loop.

Abstract

Although the time course of ST segment depression after exercise has been related to the presence and severity of coronary artery disease, recovery-phase patterns of ST segment depression with reference to changing heart rate have not been quantified. We have found distinct recovery loop patterns of ST segment depression that distinguish subjects without coronary disease from patients with coronary artery disease when ST segment depression is examined in the heart rate domain. Continuous plots of ST segment depression and heart rate were constructed throughout treadmill exercise and recovery in 100 clinically normal subjects, in 124 patients with coronary artery disease proven by catheterization, and in 17 patients with no significant coronary disease at catheterization. Among clinically normal subjects, 95% (95 of 100) had normal (clockwise) rate-recovery loops, and 5% (five of 100) had abnormal (counterclockwise) rate-recovery loops. In these normal subjects, the resulting 95% specificity of a normal rate-recovery loop was similar to the 93% (93 of 100) specificity of standard end-exercise ST segment depression criteria. Among patients with coronary disease proven by angiography, 93% (115 of 124) had abnormal (counterclockwise) rate-recovery loops, and 7% (nine of 124) had normal rate-recovery loops. In contrast was the significantly lower 74% (92 of 124) sensitivity of standard ST segment criteria (p<0.001 vs. the rate-recovery loop).Specificity of a normal rate-recovery loop (71%, 12 of 17) and standard ST segment depression criteria (71%, 12 of 17) were similar in the patients with normal coronary arteries at angiography. We conclude that the pattern of ST segment depression as a function of heart rate during exercise and recovery can markedly enhance the accuracy of the exercise electrocardiogram for the identification of coronary artery disease. (Circulation 1989;80:533-

Relation Between Platelet Response to Exercise and Coronary Angiographic Findings in Patients With Effort Angina

“…Several approaches have been proposed to this end, including extended ECG lead recording, 15 analysis of other ECG parameters, 16 more sophisticated methods of ST-segment analysis, 17,18 and multivariate scores. 19,20 Several of these methods, however, require very accurate ECG recordings for computerized analyses and/or have a less than optimal diagnostic accuracy.…”

Exercise Electrocardiogram Testing

“…23,[87][88][89][90] Data can be examined qualitatively as the simple rate-recovery loop, 91 with findings from the first minute of recovery, when patients with ischemia generally have greater ST-segment depression than was present at the corresponding heart rate during exercise before peak effort ( Figure 2). In contrast to standard ST-depression criteria and heart rate-adjusted criteria derived purely from exercise phase data, the sensitivity of the rate-recovery loop appears to be relatively independent of the extent of disease.…”

Exercise Standards for Testing and Training

“…After 1 minute of recovery, ST depression attributable to ischemia is generally greater than it was at the same HR during exercise, whereas in normal subjects it is less. 114 Extension of this principle to encompass measurement of the recovery phase area above or below the ST depression occurring with exercise forms the basis of ST/HR hysteresis, where the term hysteresis is used to indicate asymmetry of measured responses with respect to another variable occurring during exercise and recovery, such as time from peak effort, or in this case to matched HR during exercise and recovery. ST/HR hysteresis appears to provide higher diagnostic and prognostic test accuracy than that found for simultaneously measured standard ST-segment depression criteria and for the ST/HR indices.…”