[The relationship between anomalies in the autonomous nervous system and left ventricular dysfunction in patients with hypertrophic cardiomyopathy].

This study was undertaken to assess autonomic nervous system (ANS) activity and its relation to left ventricular function in 40 patients (mean age: 41 +/- 17 years) with hypertrophic cardiomyopathy (HC), in sinus rhythm, off-drugs. Patients were grouped according to the results of radionuclide angiography: 26 had an ejection fraction > 50% (Group A), whereas 14 had an ejection fraction < or = 50% (Group B). Evaluation of parasympathetic activity showed abnormalities in: heart rate (HR) response during Valsalva (< or = 1.1) in 2 Group A (8%) and 12 Group B (86%) patients (p < 0.001); HR variability during deep breathing (< or = 10 b/min) in 2 Group A (8%) and 14 Group B (100%) patients (p < 0.001); immediate HR response to standing (30:15 < or = 1.0) in 2 Group A (8%) and 6 Group B (43%) patients (p < 0.025). Assessment of sympathetic activity showed abnormalities in: systolic blood pressure fall to standing (> 20 mmHg) in 2 Group B (14%) patients only (NS); diastolic blood pressure response to handgrip (< 10 mmHg) in 4 Group B (29%) patients only (p < 0.025). Thus, in HC: impaired parasympathetic control is common in those patients showing left ventricular dysfunction; concurrent sympathetic abnormality may also occur in this subgroup of patients; ANS dysfunction seems to be merely an epiphenomenon which marks the severity of left ventricular derangement.