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Long-term j-Blockade in Dilated Cardiomyopathy

men and eight women; mean age, 47.6± 14.0 years) with dilated cardiomyopathy were studied by right and left heart catheterization, right ventricular biopsy, two-dimensional and Doppler echocardiography, and external pulse recordings. Twenty-six of 33 patients survived more than 6 months, and 24 of the 26 patients improved their functional class (from mean 3.3 to 1.8, p<0.0001). These 24 patients were subjected to withdrawal of metoprolol until the number of symptoms increased and deterioration occurred as observed noninvasively (group 1, n=16), whereas the eight patients did not deteriorate during a 12-month period (group 2). During long-term treatment with metoprolol, there was an increase in ejection fraction from 0.24 to 0.42 (p<0.000l), whereas there was a decrease in the left ventricular (LV) end-diastolic dimension (from 7.3 to 6.4 cm, p <0.0001), in the grade of mitral regurgitation (from 1.7 to 0.4, p <0.0001), and in the grade of tricuspid regurgitation (from 0.6 to 0.05, p <0.007). There was a decrease in pulmonary wedge pressure (from 23.8 to 10.7 mm Hg, p<0.0001), LV end-diastolic pressure (from 24.1 to 13.4 mm Hg, p<0.002), and systolic vascular resistance (from 1,782 to 1,499 dynes/sec/cm,p<0.04). There was an increase in systolic blood pressure (from 116 to 132 mm Hg, p<0.003), cardiac index (from 2.17 to 2.58 1/min/m2, p <0.005), and LV stroke work index (from 31 to 65 g m/m2, p<0.0001). During withdrawal of metoprolol, the heart rate and left atrial dimension increased (p <0.0001), whereas ejection fraction decreased (p <0.0001). The 12 (of 16) patients in group 1 who survived the withdrawal period had metoprolol readministered, and subsequently, ejection fraction increased (from 0.23 to 0.33,p <0.002). Patients had a low number of ventricular f3-adrenergic receptors compared with healthy control subjects (30.3+±2.9 vs. 97.4+8.7 fmol/mg protein, p<0.001), but long-term treatment with metoprolol caused a moderate up-regulation (from 30.3+±2.9 to 49.0±7.1 fmol/mg protein, p<0.05), which may facilitate a more normal response to sympathetic stimulation. We conclude that metoprolol had a beneficial clinical and hemodynamic long-term efect in patients with dilated cardiomyopathy. Withdrawal was deleterious in two thirds of the patients, and survivors benefited from readministration of the drug. (Circulation 1989;80:551-563)