Pathophysiologic significance of left ventricular hypertrophy in dilated cardiomyopathy.

BACKGROUND AND HYPOTHESIS: Patients with dilated cardiomyopathy (DCM) with left ventricular hypertrophy (LVH) have been found to have a better prognosis than patients without LVH. However, the pathophysiologic mechanism for that has not been investigated. We sought to clarify the pathophysiologic significance of LVH in DCM. METHODS: We performed isoproterenol infusion echocardiography (0.02 micrograms/kg/min) in 17 patients with DCM, and measured plasma epinephrine and norepinephrine levels at rest and at the end of ergometer exercise in 14 of the 17 patients. Patients were classified into groups according to the presence (9 patients) (LVH+) or absence (8 patients) (LVH-) of LVH. Left ventricular hypertrophy was defined as an inter-ventricular thickness or posterior wall thickness > or = 13 mm. RESULTS: Although there was no significant difference between groups in fractional shortening at rest during isoproterenol infusion, fractional shortening was significantly higher in the LVH(+) group than in the LVH(-) group (29 +/- 9 vs. 17 +/- 8%; p < 0.025). Although there was no significant difference in plasma norepinephrine level, it was significantly lower in the LVH(+) group than in the LVH(-) group (233 +/- 169 vs. 519 +/- 258 pg/ml; p < 0.05) at the end point of the exercise. CONCLUSION: Systolic reserve, represented by the response to isoproterenol, is greater in patients with DCM with LVH than in those without LVH, and a lower plasma level of norepinephrine is needed to activate the myocardium during exercise in patients with DCM with LVH. This pathophysiologic characteristic could be one of the mechanisms which explain a better prognosis in patients with DCM with LVH.

[Characteristics of myocardial diseases in the elderly].

Myocardial diseases consist of cardiomyopathy of unknown origin and specific myocardial diseases of known origin. The former consists mainly of dilated cardiomyopathy (DCM) and hypertrophic cardiomyopathy (HCM). In the latter, cardiac amyloidosis may be most frequently seen in the elderly. One hundred and twenty patients with cardiomyopathy were studied concerning their clinical courses. They were divided into 2 groups; i) young-middle-aged (Y) and ii) elderly (0). Group 1 was divided into 2 subgroups: 1a) followed up to an age less than 60 years old, and 1b) followed up to beyond age 60. In DCM, left ventricular posterior wall thickness and left atrial diameter increased significantly in the elderly. In HCM, young patients had obstructive type disease more frequently than the elderly. A history of mild hypertension was found more frequently in the middle-aged or elderly than in the young. Left ventricular end-diastolic diameter increased and left ventricular wall thickness decreased significantly in the elderly. Many patients with DCM usually die of congestive heart failure with ventricular arrhythmia, and those with HCM, both young or middle-aged, often die suddenly during sports activity. If there is an adaptive system, such as increased wall thickness in DCM or decreased wall thickness and increased diameter in HCM, which may contribute to the normalization of left ventricular wall stress, the patients might be able to survive to old age.