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

Abstract

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 < 0.05). Twenty-four-hour urinary epinephrine (E) and norepinephrine (NE) were greater than normal (E + NE excretion, 44 ± 2 vs 29.5 μg/g creatinine, p < 0.001). The short electromechanical systole corrected for heart rate (529 ± 3.9 vs normal 548 ± 2 msec, p < 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 < 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 < 0.01). It is concluded that symptomatic patients with MVP have high adrenergic tone that may be responsible for or contribute to multiple symptoms.