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Should endomyocardial biopsy be performed for detection of myocarditis? A decision analytic approach
Insights
A successful myocarditis therapy must reduce death or transplantation by at least 7.1% to justify endomyocardial biopsy (EMB). This finding aids in guiding treatment decisions for dilated cardiomyopathy patients.
Area of Science:
- Cardiology
- Immunology
- Medical Diagnostics
Background:
- Dilated cardiomyopathy (DCM) has a poor prognosis despite advances in heart failure treatment.
- Myocarditis and viral infections are potential therapeutic targets in DCM.
- The utility of endomyocardial biopsy (EMB) for diagnosing myocarditis in DCM patients is debated due to limited evidence supporting immunosuppressive therapy.
Purpose of the Study:
- To determine the required efficacy of a myocarditis treatment to justify a biopsy-guided approach over conventional therapy using decision analysis.
- To evaluate the impact of various factors, including myocarditis prevalence and EMB accuracy, on treatment decisions.
Main Methods:
- Decision analysis model incorporating literature-based estimates for myocarditis prevalence, survival rates, EMB performance, and treatment side effects.
- Sensitivity analysis was performed to assess the influence of different variables on the model's outcomes.
- Calculated the necessary risk reduction in mortality or transplantation to favor EMB-guided treatment.
Main Results:
- A treatment reducing the 5-year risk of death or transplantation by 12.7% (no borderline myocarditis) or 7.1% (borderline myocarditis) favored EMB.
- Therapeutic efficacy was most sensitive to myocarditis prevalence and biopsy-related mortality, not biopsy accuracy or treatment side effects.
- Randomized trials to detect significant risk reductions would require a large number of endpoints.
Conclusions:
- A 7.1% reduction in death or transplantation risk effectively offsets treatment side effects, EMB risks, and diagnostic inaccuracies.
- Prospective randomized trials for myocarditis treatments may be more feasible with higher disease prevalence or improved diagnostic sensitivity.
Background:
Performance of endomyocardial biopsy (EMB) to diagnose myocarditis in patients with dilated cardiomyopathy is controversial because of a lack of evidence favoring immunosuppressive therapy. In spite of advances in heart failure treatment, dilated cardiomyopathy carries a poor prognosis, and myocardial inflammation and viral infection are potential therapeutic targets.
Methods:
We used decision analysis to determine the efficacy (5-year risk reduction in mortality or transplantation) that a treatment for myocarditis would require to favor a biopsy-guided approach over conventional therapy. Literature-based estimates included prevalence of myocarditis among patients with dilated cardiomyopathy with or without borderline myocarditis (16% and 11%, respectively); probability of 5-year transplantation-free survival (55%); sensitivity (50% and 63%, respectively), specificity (95.4%), and mortality rate (0.4%) of EMB; side effects resulting in withdrawal of immunosuppressive treatment (4%); and a 6-month mortality rate for immunosuppressive treatment (0.1%). All estimates were varied to determine impact on model results (sensitivity analysis).
Results:
A therapy that decreased the rate of death or transplantation by 12.7% and 7.1% for patients without or with borderline myocarditis, respectively, favored EMB. Sensitivity analysis indicated that therapeutic efficacy was influenced by myocarditis prevalence and biopsy-related death, but not by accuracy of biopsy or probability of immunosuppressive therapy side effects. Randomized trials powered to detect 7% and 25% reductions in death and transplantation would require 5790 and 380 end points, respectively.
Conclusion:
Decreasing the rate of death or transplantation by 7.1% offsets therapy side effects, EMB-related death, and inaccuracies in histologic diagnosis. Prospective randomized trials of treatments for myocarditis may be more feasible during periods of high prevalence or with more sensitive diagnostic techniques.