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Which subgroup of patients with dilated cardiomyopathy would benefit from long-term beta-blocker therapy? A
T Yamada1, M Fukunami, M Ohmori
1Division of Cardiology, Osaka Prefectural Hospital, Japan.
Insights
Myocardial fibrosis extent and type can predict long-term beta-blocker therapy effectiveness in dilated cardiomyopathy patients. Less fibrosis, particularly interfascicular, indicates a better response to treatment.
Area of Science:
- Cardiology
- Pharmacology
- Histopathology
Background:
- Long-term beta-blocker therapy shows promise for dilated cardiomyopathy.
- Predicting treatment response is crucial for optimizing patient outcomes.
Purpose of the Study:
- To determine if pre-treatment myocardial fibrosis characteristics can predict beta-blocker therapy effectiveness.
- To identify histological markers for identifying good responders to beta-blockers.
Main Methods:
- Retrospective comparison of histological variables from endomyocardial biopsies.
- Analysis of 18 good responders versus 12 poor responders to metoprolol therapy.
- Quantification of percent fibrosis and classification of fibrosis types (interfascicular vs. intercellular).
Main Results:
- Good responders had significantly less myocardial fibrosis (7.6%) compared to poor responders (14.2%).
- Interfascicular fibrosis was dominant in good responders, while intercellular fibrosis predominated in poor responders (p < 0.001).
- Fibrosis type demonstrated high predictive accuracy (80%) for treatment response.
Conclusions:
- Myocardial fibrosis extent and type are significant predictors of beta-blocker therapy effectiveness in dilated cardiomyopathy.
- Less interfascicular fibrosis suggests a higher likelihood of positive response to long-term beta-blocker treatment.
Objectives:
The purpose of this study was to elucidate whether the effectiveness of long-term beta-blocker therapy could be predicted before this therapy is started.
Background:
Long-term beta-blocker therapy has recently been reported to provide a favorable effect in treatment of congestive heart failure due to dilated cardiomyopathy.
Methods:
Several measurements including histologic variables before administration of metoprolol were retrospectively compared among 18 good responders (showing improvement of at least one New York Heart Association functional class or an increase in ejection fraction > or = 0.10 12 months after drug administration) and 12 poor responders without such improvement.
Results:
Although there were no significant differences between the two groups in age, gender, functional class, heart rate, blood pressure, pulmonary capillary wedge pressure, cardiac index, left ventricular end-diastolic dimension and ejection fraction, percent fibrosis estimated by the point-counting method in endomyocardial biopsy specimens was significantly lower in good than in poor responders (7.6 +/- 5.7 vs. 14.2 +/- 9.7%, p < 0.05). Moreover, when the types of fibrosis were classified as interfascicular and intercellular by the dominance of counted points, there were 13 cases of interfascicular fibrosis and 5 cases of intercellular fibrosis in good responders and 1 case of interfascicular fibrosis and 11 cases of intercellular fibrosis in poor responders (p < 0.001, sensitivity 72%, specificity 91%, predictive accuracy 80%). These results suggest that improvement with long-term beta-blocker therapy may be more likely to occur in patients with less myocardial fibrosis, with interfascicular fibrosis the dominant type.
Conclusions:
The extent and type of fibrosis may be important factors in the prediction of the effectiveness of long-term beta-blocker therapy for dilated cardiomyopathy.