Transradial left ventricular endomyocardial biopsy feasibility, safety and clinical usefulness: Initial experience of a tertiary university center.

INTRODUCTION AND OBJECTIVES: Over the last decade, several studies have suggested that left ventricular endomyocardial biopsy is safer and has a higher diagnostic yield than transvenous right ventricular biopsy. In addition, recent publications indicate that the transradial approach is a feasible and safe alternative to the transfemoral approach for sampling the left ventricle. We report our initial experience with transradial endomyocardial biopsy with regards to feasibility, safety and usefulness. METHODS: Single-center registry of consecutive patients undergoing intended transradial left endomyocardial biopsy. Clinical and technical data were collected prospectively, with a particular focus on success rate and complications. RESULTS: Twenty-seven patients were screened for left ventricle biopsy. Twenty (25) were selected for an intended transradial approach (mean age 51±18 years old, 22 male). Success rate was 100% with no crossover to femoral approach. There were no major complications. Two patients experienced mild radial spasm. One of them also had a run of non-sustained ventricular tachycardia. Indication for biopsy was either myocarditis or cardiomyopathy of unknown etiology. The final diagnosis was acute lymphocytic myocarditis in five patients, chronic myocarditis in one patient, amyloid light-chain amyloidosis in four patients and transthyretin amyloidosis in six patients. Myocarditis was ruled out in eight patients and amyloidosis in one patient. CONCLUSIONS: Transradial left ventricle endomyocardial biopsy is a very safe and feasible method of sampling the myocardium for histopathological analysis, with a good diagnostic yield and clinically meaningful results in properly selected patients.

Progression of myocardial sympathetic denervation assessed by 123I-MIBG imaging in familial amyloid polyneuropathy and the effect of liver transplantation. / Progressão da desnervação simpática cardíaca avaliada por cintigrafia com MIBG­I123 na polineuropatia amiloidótica familiar e o impacto da transplantação hepática.

INTRODUCTION: Familial amyloid polyneuropathy (FAP) is a rare disease caused by systemic deposition of amyloidogenic variants of the transthyretin (TTR) protein. The TTR-V30M mutation is caused by the substitution of valine by methionine at position 30 and mainly affects the peripheral and autonomic nervous systems. Cardiovascular manifestations are common and are due to autonomic denervation and to amyloid deposition in the heart. Cardiac sympathetic denervation detected by iodine-123 labeled metaiodobenzylguanidine (MIBG) is an important prognostic marker in TTR-V30M FAP. Liver transplantation, widely used to halt neurological involvement, appears to have a varying effect on the progression of amyloid cardiomyopathy. Its effect on the progression of cardiac denervation remains unknown. METHODS: In this observational study, patients with the TTR-V30M mutation underwent annual cardiac assessment and serial MIBG imaging with quantification of the late heart-to-mediastinum (H/M) ratio. RESULTS: We studied 232 patients (median age 40 years, 54.7% female, 37.9% asymptomatic at the time of inclusion) who were followed for a median of 4.5 years and underwent a total of 558 MIBG scans. During follow-up, 47 patients (20.3%) died. MIBG scintigraphy at inclusion was a strong predictor of prognosis, with the risk of death increasing by 27.8% for each one-tenth reduction in the late H/M ratio. The late H/M ratio decreased with age (0.082/year, p<0.001), but progression of cardiac denervation was so slow that annual repetition of MIBG imaging did not increase its prognostic accuracy. During follow-up, 70 symptomatic patients underwent liver transplantation. The late H/M ratio decreased by 0.19/year until transplantation but no statistically significant differences were detected after the procedure. CONCLUSIONS: Cardiac denervation is common during the progression of TTR-V30M FAP and quantification of the late H/M ratio on MIBG scintigraphy is valuable for prognostic stratification of these patients. Liver transplantation stabilizes cardiac denervation, without recovery or further deterioration in cardiac MIBG uptake after the procedure.