Heart rate and blood pressure in mitral valve prolapse patients: divergent effects of long-term propranolol therapy and correlations with catecholamines.

OBJECTIVE: There is a well known association between mitral valve prolapse (MVP) and low blood pressure (BP), although patients often have high levels of catecholamines and high heart rate (HR). The main objective of our study was to evaluate the effects of long-term adrenergic beta-blockade on these parameters. METHODS: The study population consisted of 46 patients with MVP and the control group consisted of 20 normal individuals. The study had two phases: in the first phase, patients were free of medications. In the second phase, patients were under treatment with propranolol for 10 to 12 months. The tests were performed in normal individuals and patients in the first phase. Only patients underwent the same tests in the second phase. Measurement of urinary epinephrine and norepinephrine levels, by high performance liquid chromatography, was done. Rest HR was determined by electrocardiogram (ECG), and ambulatory blood pressure and HR were evaluated by 24 hours ambulatory blood pressure monitoring (ABPM) using the auscultatory method. RESULTS: The levels of epinephrine and norepinephrine were significantly higher in patients than in normal controls and decreased under propranolol. Rest and ambulatory HR were higher in patients and decreased under propranolol. The 24 hours systolic and diastolic BPs were lower in patients, and their values increased under propranolol. Heart rate decreasing and epinephrine levels reduction were positively correlated. No correlation was found between BP increase and catecholamine levels. CONCLUSION: The study results show divergent effects of propranolol on blood pressure, which increased, and on heart rate, that decreased, in patients with MVP. Heart rate decrease was an expected result and depends, namely, on b1 receptors blockade. Increase in BP is an unusual response to adrenergic beta-blockade in normal conditions, and this finding supports the preponderance of b2 receptors on the BP control in patients with MVP.

Plasma N-terminal pro-brain natriuretic peptide: a marker of left ventricular hypertrophy in hypertrophic cardiomyopathy.

BACKGROUND: B-type natriuretic peptide is secreted mainly in the left ventricle in response to elevated wall tension. Plasma levels of the peptide correlate positively with cardiac filling pressures, making it an excellent marker for the presence of left ventricular dysfunction. In hypertrophic cardiomyopathy, enhanced production of B-type natriuretic peptide is observed. However, the relationship of the various structural and functional features present in the disease with the high plasma levels described is not yet fully clarified. In the present study, we prospectively assessed in hypertrophic cardiomyopathy the relationship of plasma NT-proBNP levels with the extent of left ventricular hypertrophy, presence of left ventricular outflow obstruction and echocardiographic parameters of left ventricular diastolic function. METHODS: The study population included 190 individuals: 53 patients with hypertrophic cardiomyopathy and well-preserved left ventricular systolic function (group A), 92 healthy relatives with no disease expression (group B), and an additional group of 46 healthy volunteers (group C) as controls for NT-proBNP levels. Groups A and B were characterized clinically and by echocardiography and compared with each other. Plasma NT-proBNP levels were measured (ECLIA-Elecsys proBNP) and compared in the 3 groups of individuals included in the study. In hypertrophic cardiomyopathy patients, correlation was sought between NT-proBNP levels, NYHA functional class and echocardiographic data. RESULTS: Groups A and B differed (p < 0.001) in septal thickness, maximal wall thickness, left ventricular hypertrophy score, left atrial size, left atrial fractional shortening, derived transmitral filling indices and plasma NT-proBNP levels (group A: 909.9 +/- 1554.2 pg/ml; group B: 40.7 +/- 45.1 pg/ml). Left ventricular diastolic size and pulmonary venous flow velocity-derived indices were similar in the 2 groups. NT-proBNP levels in group B and C (39.4 +/- 34.5 pg/ml) were similar (p = NS). In hypertrophic cardiomyopathy patients, NT-proBNP levels correlate directly with NYHA functional class (r = 0.56, p < 0.001), septal thickness (r = 0.53, p < 0.001), maximal wall thickness (r = 0.59, p < 0.001), left ventricular hypertrophy score (r = 0.63, p < 0.001), left atrial size (r = 0.32, p = 0.023) and mitral deceleration time (r = 0.46, p = 0.001) and inversely with left atrial fractional shortening (r = -0.41, p = 0.005). Functional class also correlates directly with left ventricular hypertrophy score (r = 0.39, p = 0.006), with the most symptomatic patients having the highest scores. CONCLUSIONS: In hypertrophic cardiomyopathy, plasma NT-proBNP levels depend mainly on the severity of left ventricular hypertrophy rather than on the presence of obstruction. Measurement of the peptide may help in the clinical characterization and follow-up of patients with this disease.