The correlation of recovery-positive treadmill exercise testing with coronary artery disease.

In the light of the controversial clinical relevance of ST segment depression confined to the recovery period of an otherwise "normal" treadmill exercise test, the tracings of 51 male patients at St. Lukes Medical Center Heart Institute from 1987 to May 1992 who presented with this stress test ECG change were reviewed and correlated with the coronary angiography findings. Lachtermans Scoring System to quantify the severity of CAD based on angiographic profile was adopted in this study. Twenty-seven percent (14/51) of the subjects had normal angiographic findings; in this same subgroup, all showed ST-T changes confined to the inferior leads only. In the remaining 73% (37/51) who had abnormal coronary angiograms, 20% (10/51) showed ECG changes confined to the inferior leads and the remaining 53% (27/51) had ECG changes in leads other than the inferior; in this 53% subgroup, 14/27 nevertheless had significant RCA lesions, giving a sensitivity of 42% in the use of inferior leads in the detection of CAD. Limiting the population to 27 by excluding those with inferior lead involvement, there was a good correlation of significantly-diseased coronaries when the ST segment depression in the recovery period occurred earlier (mean = 5.08 + 2.2. min., r = -.8863), was of longer duration (mean = 5.5 + 2.7 min., r = .8800), and was associated with lower METS (mean = 8.0 + 2.5 METS, r = -.8027) and lower Double Product (mean = 14820 +/- 4204.8, r = -.8048) achieved. There was poor correlation of the severity of diseased coronaries with the depth of ST segment depression, be it 1 mm or more. Correlation was improved further when two or more of these characteristics were present, with the best correlation coefficient of .9784 achieved when all four variables were present. This paper further supports a previous contention on the low sensitivity of the inferior ECG leads in the detection of CAD.