Coronary adrenergic hyperreactivity in patients with syndrome X and abnormal electrocardiogram at rest.

Syndrome X is characterized by an abnormal vasomotility of coronary microvessels. It is unknown whether the presence of an ischemic-like pattern in the electrocardiogram at rest (T-wave inversion) reflects a more severe vasomotion disturbance. Changes in coronary sinus flow (thermodilution) and epicardial vessel diameter (quantitative angiography) during adrenergic activation were measured with a standard cold pressor test in patients with syndrome X whose electrocardiogram at rest was normal (group 1: 17 patients) or showed stable, symmetrically inverted T waves (group 2: 22 patients). Cold pressor test increased mean blood pressure and rate-pressure product to a similar extent in both groups, increased coronary sinus flow in group 1 (88 +/- 29 to 119 +/- 36 ml/min; p less than 0.05) and not in group 2 (109 +/- 37 vs 104 +/- 36 ml/min; p = not significant), and decreased coronary resistance in group 1 (1.38 +/- 0.42 to 1.19 +/- 0.38 mm Hg/ml/min; p less than 0.05) and augmented it in group 2 (1.06 +/- 0.32 to 1.28 +/- 0.43 mm Hg/ml/min; p less than 0.02). During cold stimulus, the proximal and middle segments of epicardial arteries showed negligible changes in their lumen, whereas the distal segment dilated in group 1 (1.81 +/- 0.27 to 2.01 +/- 0.32 mm; p less than 0.05) and constricted in group 2 (1.82 +/- 0.12 to 1.62 +/- 0.20 mm; p less than 0.05). Differences in coronary hemodynamic and angiographic responses between the groups were statistically significant (p less than 0.05).(ABSTRACT TRUNCATED AT 250 WORDS)