Should endomyocardial biopsy be performed for detection of myocarditis? A decision analytic approach.
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.


CONCLUSIONS
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.
Hrobon
P
P
Harvard School of Public Health, Boston, Mass, USA.
Kuntz
K M
KM
Hare
J M
JM
D001706:Biopsy; D002311:Cardiomyopathy, Dilated / Q000401:mortality / Q000473:pathology*; D002423:Cause of Death; D003661:Decision Support Techniques; D004699:Endocardium / Q000473:pathology*; D016027:Heart Transplantation / Q000401:mortality; D006801:Humans; D007166:Immunosuppressive Agents / Q000009:adverse effects / Q000627:therapeutic use; D015233:Models, Statistical; D009205:Myocarditis / Q000401:mortality / Q000473:pathology*; D009206:Myocardium / Q000473:pathology*; D011379:Prognosis; D012307:Risk Factors; D012680:Sensitivity and Specificity; D015996:Survival Rate; D016896:Treatment Outcome
D007166:Immunosuppressive Agents