Flail tricuspid leaflet has been reported as a relatively uncommon complication of endomyocardial biopsy in orthotopic heart transplant recipients. However, the relationship of this complication to the number of biopsies performed and to the site of access for biopsy is not known. The objectives of this study were to assess the prevalence of flail tricuspid leaflet/torn chordae tendineae in our recent transplant population, define the relationship of this complication to endomyocardial biopsy, and to correlate echocardiographic assessments of tricuspid regurgitation severity with hemodynamic data obtained at cardiac catheterization. From January 1991 to March 1993, 181 patients who had undergone orthotopic heart transplantation at our institution were evaluated with echocardiography for the presence of a flail leaflet or torn chordae tendineae of the tricuspid valve and tricuspid regurgitation. After identifying this complication in patients, we reviewed their hemodynamic tracings and biopsy protocols from the catheterization laboratory. The hemodynamic tracing chosen was that which was done at the time the flail leaflet was first diagnosed. Of the 181 patients, 21 (11.6%) had flail leaflet or torn chordae tendineae of the tricuspid valve. The group comprised 18 male and 3 female patients. The mean duration from the time of transplantation was 42 months (range, 1 to 87 months). The mean number of biopsies performed per patient was 15.5 (range, 2 to 27). The mean severity of tricuspid regurgitation by echocardiography was grade 3 (moderate); seven patients (33%) had severe regurgitation. The mean right atrial v wave by catheterization was 15 mm Hg (range, 6 to 26 mm Hg).(ABSTRACT TRUNCATED AT 250 WORDS)