Abstract
Background
Exercise-induced ST changes, suggestive of cardiac ischaemia, are found in asymptomatic patients. Methods Gas exchange kinetics were studied during exercise to help to separate patients affected by epicardial coronary disease from those without. Forty-eight patients, without angina symptoms and showing significant changes of ST during exercise, underwent a coronarography and maximal cardiopulmonary exercise test. Thirty-five healthy individuals of matched age and sex underwent a cardiopulmonary exercise test as controls.
Results
Patients were grouped according to the presence (group 1, n = 35) or the absence (group 2, n = 13) of significant coronary lesions at angiography. When corrected for predicted oxygen consumption (VO 2) at peak exercise and at anaerobic threshold, results showed a low VO 2 at peak exercise and anaerobic threshold in group 1 (68 ± 19 and 84 ± 17% of predicted, respectively) compared with normal subjects (91 ± 19 and 96 ± 24% of predicted VO 2) and group 2 patients (86 ± 17 and 96 ± 18%). Also the ischaemic threshold, when normalized for predicted workload at peak exercise, occurred earlier in group 1 (67 ± 22%) than in group 2 (87 ± 19%). The time-related (δ)VO 2/δwork relationship showed a significant flattening above the anaerobic threshold in group 1 (7.4 ± 2.2 versus 9.4 ± 1.4 ml/watt per minute, P<0.01), but not in controls or in group 2. Also the δVO 2/δwork relationship, above the ischaemic threshold, flattened in group 1, but not in group 2.
Conclusion
The suggestion of major coronary disease in patients with exercise-induced ST changes is given by: (i) a flattening of the δVO 2/δwork relationship, above both the ischaemic and anaerobic thresholds; and (ii) low VO 2 values at anaerobic and ischaemic thresholds.
Get full access to this article
View all access options for this article.