Changes in myocardial cytoskeletal intermediate filaments and myocyte contractile dysfunction in dilated cardiomyopathy: an in vivo study in humans.

AIM: To investigate in vivo the intermediate cytoskeletal filaments desmin and vimentin in myocardial tissues from patients with dilated cardiomyopathy, and to determine whether alterations in these proteins are associated with impaired contractility. METHODS: Endomyocardial biopsies were performed in 12 patients with dilated cardiomyopathy and in 12 controls (six women with breast cancer before anthracycline chemotherapy and six male donors for heart transplantation). Biopsy specimens were analysed by light microscopy and immunochemistry (desmin, vimentin). Myocyte contractile protein function was evaluated by the actin-myosin in vitro motility assay. Left ventricular ejection fraction was assessed by echocardiography and radionuclide ventriculography. RESULTS: Patients with dilated cardiomyopathy had a greater cardiomyocyte diameter than controls (p < 0.01). The increase in cell size was associated with a reduction in contractile function, as assessed by actin-myosin motility (r = -0.643; p < 0.01). Quantitative immunochemistry showed increased desmin and vimentin contents (p < 0.01), and the desmin distribution was disturbed in cardiomyopathy. There was a linear relation between desmin distribution and actin-myosin sliding in vitro (r = 0.853; p < 0.01) and an inverse correlation between desmin content and ejection fraction (r = -0.773; p < 0.02). Negative correlations were also found between myocardial vimentin content and the actin-myosin sliding rate (r = -0.74; p < 0.02) and left ventricular ejection fraction (r = -0.68; p < 0.01). CONCLUSIONS: Compared with normal individuals, the myocardial tissue of patients with dilated cardiomyopathy shows alterations of cytoskeletal intermediate filament distribution and content associated with reduced myocyte contraction.

Treatment of hypertension associated with stable angina pectoris: favourable interaction between new metoprolol formulation (OROS) and nifedipine.

This was a double-blind, within-patient, crossover study to evaluate the effects of a new formulation of metoprolol on blood pressure (BP) and myocardial ischemia. Twenty outpatients with mild to moderate essential arterial hypertension, chronic stable angina pectoris and positive exercise test, after a 2-week baseline placebo period, were randomized to receive long-acting metoprolol (OROS) 14/190 mg o.d., nifedipine SR 20 mg b.i.d. or their combination in a sequence of a 3 x 3 Latin square design. Two patients withdrew from the study (1 for adverse event during metoprolol and 1 for rise of BP during nifedipine). Nifedipine, metoprolol and their combination significantly reduced the weekly number of angina attacks and nitroglycerin consumption with respect to baseline. The total number of ischemic events (at 24-hour ECG monitoring) significantly decreased after each treatment with respect to baseline. Twenty-four hours mean systolic and diastolic BP were reduced by both nifedipine alone and metoprolol alone; the combination of the two drugs led to a further decrease in both systolic and diastolic BP. The duration of silent ischemic episodes was significantly reduced by nifedipine and combination but not by metoprolol. On the other hand 24 hours symptomatic attacks/patient were significantly reduced by beta-blocker and combination, but not by nifedipine. Metoprolol alone and administered with nifedipine caused a decrease, with respect to placebo baseline, in 24-hour mean heart rate (HR) and reduced the increase of HR and systolic BP at the onset of ST depression during symptomatic ischemic episodes. The effort time and time to ST = -1 mm at treadmill were significantly increased by treatment with nifedipine alone, with metoprolol alone and with their combination, but the combination was more effective than the individual therapies. ST depression at peak exercise was significantly reduced by each treatment. The slopes of correlations between the ST-segment variation and systolic BP, HR and rate-pressure product during exercise, significantly decreased after all treatments with respect to placebo baseline, more with the combination therapy than with nifedipine alone and metoprolol alone. In conclusion, based on our results the favourable interaction of metoprolol OROS and nifedipine given concomitantly, is likely to be due to a better control, respect to each individual therapy, of the pathogenetic mechanism of myocardia ischemia: BP and HR increases during exercise and during symptomatic ischemic episodes are controlled by the beta-blocker and coronary vasoconstriction during silent ischemia is prevented by the calcium-antagonist.