Metabolic studies in mitral valve prolapse syndrome. A neuroendocrine--cardiovascular process.

Symptomatic patients with mitral valve prolapse (MVP) frequently mimic thyrotoxicosis, hyperadrenergic states or hypoglycemia. Twenty symptomatic patients with auscultatory and echocardiographic MVP were studied in the clinical research unit. T3, T4 and plasma cortisol were normal. Patients with MVP had normal responses to oral glucose administration but higher glucose levels than the controls (p less than 0.05). Twenty-four-hour urinary epinephrine (E) and norepinephrine (NE) were greater than normal (E + NE excretion, 44 +/- 2 vs 29.5 microgram/g creatinine, p less than 0.001). The short electromechanical systole corrected for heart rate (529 +/- 3.9 vs normal 548 +/- 2 msec, p less than 0.01) also reflected high adrenergic tone. Frequent premature ventricular complexes (PVCs) with couplets and triplets were found in 14 patients. Catecholamine excretion and frequency of PVCs were parallel and both decreased significantly at night (p less than 0.001). Plasma catecholamine increase with exercise was greater in patients in whom the number of PVCs increased more than 10 per minute compared with patients in whom the number of PVCs remained relatively unchanged (620 +/- 80 vs 98 +/- 20 msec, p less than 0.01). We conclude that symptomatic patients with MVP have high adrenergic tone that may be responsible for or contribute to the multiple symptoms.