Cardiac syndrome X, intraventricular gradients and, beta-blockers

Development of intraventricular gradients (IVG) on exertion seldom occurs in an unselected population. We performed exercise stress echocardiography (SE) in a 23-year-old athlete with a positive treadmill ECG and normal resting echocardiogram, but without angiographically demonstrable coronary disease (cardiac syndrome X), during which he developed an IVG of 102 mmHg and systolic anterior motion (SAM) of the mitral valve. Subsequently, we performed SE in 91 patients, 44 of whom were women, mean age 51.4 +/- 12.1 years (20-72), under similar circumstances--positive treadmill testing and no angiographically demonstrable coronary disease. In 33 (36%) of these, SE disclosed IVG with a mean end-systolic peak of 86 +/- 34 mmHg (30-165), together with mitral valve SAM in 23. The 20 patients who repeated SE under beta-blocker therapy constitute the study population. Seven (35%) of them were women, mean age 50.7 +/- 13.4 years (23 to 72).

To assess the effect of beta-blockers on the occurrence of IVG and mitral valve SAM in patients with cardiac syndrome X.

We repeated SE in 20 of the 33 patient that developed IVG on exertion, under beta-blocker therapy. They all underwent 2D and Doppler echocardiographic assessment before, during and after treadmill exercise.

Mean IVG in the 20 patients in the study population was 971 +/- 31 mmHg on the first SE assessment. In the assessment performed under beta-blocker therapy, 11 did not develop IVG, and in 9 the gradient was significantly reduced, to a mean of 46 +/- 13 mmHg. Mean heart rate at peak exercise was 161 +/- 17 bpm in the first SE assessment and 143 +/- 12 bpm under treatment with beta-blockers (p < 0.0001). Fifteen of these patients showed clinical improvement during follow-up, while no change in clinical status was seen in the other five.

In patients with cardiac syndrome X and IVG on exertion, treatment with oral beta-blockers prevented the occurrence of IVG or significantly reduced their magnitude. These changes were associated with significant reduction in heart rate at peak exercise and with clinical improvement in 75% of the study population.