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Long-term outcome of patients with biopsy-proved myocarditis: comparison with idiopathic dilated cardiomyopathy
M Grogan1, M M Redfield, K R Bailey
1Division of Cardiovascular Diseases and Internal Medicine, Mayo Clinic, Rochester, Minnesota 55905, USA.
Insights
Patients with lymphocytic myocarditis have a poor long-term outcome, similar to those with idiopathic dilated cardiomyopathy. Endomyocardial biopsy has limited prognostic value for dilated cardiomyopathy when excluding myocarditis.
Area of Science:
- Cardiology
- Pathology
Background:
- Endomyocardial biopsy is used to diagnose lymphocytic myocarditis in patients with dilated cardiomyopathy.
- Previous studies on myocarditis natural history predate standardized diagnostic criteria (Dallas criteria).
- Evaluating the prognostic significance of Dallas criteria-positive biopsies in dilated cardiomyopathy is crucial.
Purpose of the Study:
- To assess the long-term outcome of patients diagnosed with lymphocytic myocarditis (Dallas criteria).
- To compare the outcomes of lymphocytic myocarditis patients with those of idiopathic dilated cardiomyopathy patients.
Main Methods:
- Reclassified endomyocardial biopsy results from Mayo Clinic (1979-1988) using Dallas criteria.
- Included patients with borderline or lymphocytic myocarditis, excluding those with systemic inflammatory diseases.
- Compared survival rates between the myocarditis group and a cohort with idiopathic dilated cardiomyopathy (1976-1987).
Main Results:
- 27 patients met Dallas criteria for myocarditis (28) or borderline myocarditis (13) after exclusions.
- The myocarditis group had a higher NYHA functional class (63%) than the dilated cardiomyopathy group (30%).
- No significant difference in 5-year survival rates was observed between the groups (56% vs. 54%).
Conclusions:
- Biopsy-proven lymphocytic myocarditis in a referral setting is associated with a poor long-term prognosis.
- The long-term outcome for myocarditis patients is similar to that of idiopathic dilated cardiomyopathy patients.
- Endomyocardial biopsy has limited prognostic value in routine dilated cardiomyopathy evaluation due to lack of proven treatments and demonstrated survival benefits.
Objectives:
The study objectives were 1) to assess the long-term outcome of patients with biopsy-proved lymphocytic myocarditis (Dallas criteria), and 2) to compare the outcome of these patients with that of patients with idiopathic dilated cardiomyopathy.
Background:
Endomyocardial biopsy is frequently performed in patients presenting with dilated cardiomyopathy to identify lymphocytic myocarditis. Most previous studies of the natural history of myocarditis were performed before the establishment of the Dallas criteria. Thus, it is important to evaluate the prognostic value of positive endomyocardial biopsy findings in patients presenting with dilated cardiomyopathy, using standardized criteria for lymphocytic myocarditis.
Methods:
All endomyocardial biopsy results from the Mayo Clinic (October 1979 to April 1988) with a diagnosis of myocarditis were reclassified according to the Dallas criteria. Patients whose biopsy specimens showed borderline or lymphocytic myocarditis were included in the study group; those with systemic inflammatory diseases known to be associated with myocardial involvement were excluded. Study group survival was compared with that for a cohort of patients with idiopathic dilated cardiomyopathy seen at the Mayo Clinic from 1976 to 1987 who had endomyocardial biopsy findings negative for myocarditis.
Results:
Biopsy specimens from 41 patients met the Dallas criteria for a diagnosis of myocarditis (n = 28) or borderline myocarditis (n = 13). Of these 41 patients, 9 were excluded because of the presence of systemic diseases known to be associated with myocarditis, and 5 patients were excluded because of lack of available follow-up data. The myocarditis study group therefore included 27 patients (10 with borderline myocarditis, 17 with myocarditis). Fifty-eight patients with a diagnosis of idiopathic dilated cardiomyopathy who underwent endomyocardial biopsy served as the comparison cohort. Ejection fraction was lower in patients with idiopathic dilated cardiomyopathy ([mean +/- SD] 25 +/- 11%) than in those with myocarditis (38 +/- 19%, p = 0.001), even though a higher proportion of myocarditis group patients were in New York Heart Association functional class III or IV (63%) than patients in the dilated cardiomyopathy group (30%, p = 0.005). There was no difference in 5-year survival rate between the myocarditis and idiopathic dilated cardiomyopathy groups (56% vs. 54%, respectively).
Conclusions:
This study demonstrates that the long-term outcome of patients with biopsy-proved myocarditis seen in a referral setting is poor, although no different from that of patients with idiopathic dilated cardiomyopathy. With the current lack of proved effective treatment for lymphocytic myocarditis and no demonstration of survival benefit for patients with myocarditis, these data suggest that endomyocardial biopsy performed to exclude myocarditis is of limited prognostic value in the routine evaluation of dilated cardiomyopathy.