Does endomyocardial biopsy aid in the diagnosis of active rheumatic carditis?

Carditis is the only component of rheumatic fever that leads to permanent disability. The diagnosis of carditis is presently made by using composite clinical criteria based on the revised Jones' criteria. Since myocardial involvement is an important component of rheumatic carditis, right ventricular endomyocardial biopsies were performed in 54 patients with clinical acute rheumatic fever and quiescent rheumatic heart disease to evaluate the role of biopsy for the diagnosis of rheumatic carditis.

In 11 of the 54 patients, clinical consensus was certain about rheumatic fever and carditis based on the revised Jones' criteria (group 1). Histomorphological abnormalities in these patients were scarce. The diagnostic features of rheumatic myocarditis including Aschoff nodules or histiocytic aggregates were encountered in 3 patients (27%). Lymphocytic infiltration was sparse. A majority of patients demonstrated myocyte degeneration, interstitial degeneration, or occasional interstitial mononuclear cell infiltration, but since these histopathological lesions may occur in other conditions also, they were considered nondiagnostic. In 33 of the 54 patients with preexisting rheumatic heart disease, the diagnosis of carditis was suspected based on varied clinical presentations. Since previous cardiac findings were not available in these patients, the clinical diagnosis of carditis could not be made without equivocation (group 2). Twenty-three patients presented with unexplained acute onset of congestive heart failure and evidence of recent streptococcal infection (group 2A). While 13 of them had one or more other major manifestations, 10 patients had only minor manifestations. Mimetic carditis was suspected in the remaining 10 of 33 patients based on carditis having occurred in previous episodes of rheumatic fever (group 2B). The endomyocardial biopsy provided confirmatory evidence of rheumatic myocarditis in 9 patients of group 2A but in none of the 10 patients with suspected mimetic carditis. Nondiagnostic myocyte or interstitial alterations were frequently observed in group 2. Ten of the 54 patients had no clinical evidence of active carditis (group 3). No histological alterations diagnostic of rheumatic carditis were noted in these patients. Twenty-two follow-up biopsies were performed in the first 10 consecutive patients. Diagnostic histiocytic aggregates or Aschoff nodules were observed in initial biopsies in 4 of 10 patients, and nonspecific myocyte or interstitial alterations were observed in 9. All patients with diagnostic changes in initial biopsy demonstrated fibrohistiocytic nodules in 6- or 12-week biopsy samples. Nondiagnostic alterations, similar to those seen in acute cases, were present in 5 of 8 patients at 6 weeks, 5 of 8 patients at 12 weeks, and 3 of the 6 patients at 24 weeks despite the presumed adequate immunosuppressive therapy. No complications related to biopsy were encountered.

The present study highlights the low frequency of diagnostic features in the biopsy specimens of patients with definite clinical rheumatic carditis. Although such alterations are not observed in patients with chronic rheumatic heart disease, endomyocardial biopsy does not appear to provide additional diagnostic information where clinical consensus is certain about diagnosis of rheumatic carditis. Our study, however, substantiates the concept of carditis underlying unexplained congestive heart failure of acute onset in patients with preexisting rheumatic heart disease and elevated antistreptolysin-O titers.