Diagnostic contribution of left ventricular endomyocardial biopsy in patients with clinical phenotype of hypertrophic cardiomyopathy

Hypertrophic cardiomyopathy phenotype is shared by heterogeneous entities. The purpose of the study was to evaluate the diagnostic role of left ventricular endomyocardial biopsy. One hundred fifty-one consecutive patients with unexplained left ventricular hypertrophy and normal/elevated QRS voltages or left bundle-branch block underwent left ventricular endomyocardial biopsy because of associated left ventricular dysfunction (37%), presence of sporadic form of left ventricular hypertrophy (32%), or patient desire for a definite diagnosis (31%). Biopsy samples were processed for histology and electron microscopy. Blood samples were collected for histologically oriented gene analysis of major sarcomeric (MYH7, MYBPC3, TNNT2, TPM1) and lysosomal (LAMP2, PRKAG2, α-galactosidase A) proteins. Histology showed changes consistent/compatible with hypertrophic cardiomyopathy in 124 patients: myocardial storage disease in 18 due to Fabry disease in 12 and glycogen-storage disease in 6 and myocardial infiltrative disease in 9 because of amyloidosis in 7 and sarcoidosis in 2. Gene analysis was positive in 67% of patients with hypertrophic cardiomyopathy (MYH7 mutation in 36, MYBP in 29, TNNT2 in 14, and TPM1 in 5) and in 83% of patients with lysosomal storage disease (α-galactosidase A mutation in 12, PRKAG2 in 2, and LAMP2 in 1). In patients with hypertrophic cardiomyopathy phenotype, left ventricular endomyocardial biopsy is safe and may recognize infiltrative/storage diseases in up to 18% of evolving and sporadic cases.