Endpoints of treadmill exercise testing for functional evaluation of patients with mitral stenosis

The study was performed on 122 patients proved by catheterization to have dominant mitral stenosis so as to define proper endpoints of exercise testing for functional evaluation. This represents the 14-year experience with mitral stenosis in our exercise laboratory. Of them, we investigated 126 who completed clinically event-free Naughton treadmill exercise tests. Excess peak exercise heart rates (over 150 beats per minute, 63%) and exertional hypotensive responses (59%, probably including factitious responses due to unreliable indirect pressure readings) did not correlate with the severity of mitral stenosis. Without limiting symptoms and major ventricular arrhythmias, either of the above as endpoints may cause the test to be halted prematurely in half the cases. Ventricular arrhythmias (60%; in complex forms, 20%; possibly contaminated by aberrancy in atrial fibrillation and aggravated by digitalis/diuretics) did not correlate with severity of stenosis either, but the only one major complication we met was secondary to ventricular tachyarrhythmia. Limiting symptoms (83%; of them 94% being dyspnea/fatigue correlating with severity at P less than 0.01) and complex ventricular arrhythmias as endpoints terminated 85% of the tests safely in this series. Atrial thrombuses (34%, all non-floating) did not cause any related complications. Thus, we concluded that limiting symptoms and complex ventricular arrhythmias are the proper endpoints in evaluating the exercise capacity of patients with mitral stenosis after prior echocardiographic exclusion of those with potentially risky floating thrombus.