Right ventricular function during pharmacological and exercise stress testing in horses

Heart rate, systemic blood pressure and cardiac output during echocardiography were similar post-exercise compared to maximal pharmacological stress. Systolic pulmonary artery pressure was significantly higher during the exercise test (121 ± 15 mmHg) and during immediate post-exercise echocardiography (93 ± 10 mmHg) compared to maximal pharmacological stress (69 ± 12 mmHg). Right ventricular diameters as well as the ratio of systolic right to left ventricular area were higher post-exercise. Right ventricular fractional area change was significantly decreased post-exercise (40.5 ± 6.2%) compared to a significant increase during pharmacological stress echocardiography (72.6 ± 7.3%). Serum cardiac troponin I concentration was significantly higher 2 h after the pharmacological test compared to baseline values and post-exercise, although the highest value was found post-exercise in the horse with the highest systolic pulmonary artery pressure and lowest right ventricular fractional area change. Pharmacological stress testing is not recommended in further studies on right ventricular adaptations in athletic horses, as this does not reproduce the effects of exercise.