Prognostic value of age-sex adjusted NT-proBNP ratio in obstructive hypertrophic cardiomyopathy.

Background: We sought to determine the incremental prognostic value of age-sex adjusted N-terminal prohormone brain natriuretic peptide (NT-pro BNP) ratio in obstructive hypertrophic cardiomyopathy (oHCM) patients.

Methods: The study included 2119 consecutive oHCM patients (age 55 ± 13 years, 53% men, maximal LVOT ≥30 mmHg) evaluated between 6/2002-12/2018 with BNP or NT-pro BNP measured at baseline. NT-pro BNP ratio was calculated as: NT-proBNP/ upper limit of normal NT-proBNP derived from age-sex matched controls. Septal reduction therapy (SRT) during follow-up was recorded. Primary endpoint was death, need for cardiac transplantation or appropriate internal cardioverter defibrillator (ICD) discharge.

Results: Median NT-proBNP ratio was 5.4 (IQR 2.1-12.3). Using spline analysis, log-transformed NT-pro BNP ratio of 2 (corresponding to NT-pro BNP ratio of 6) was the optimal value where primary endpoint hazards crossed 1; there were 966 patients with high and 1153 patients with low NT-pro BNP ratio. 1665 (79%) patients underwent SRT at 47 days (IQR 7-128 days). At 5.4 years of follow-up (IQR 2.8-9.2 years), the primary outcome occurred in 315 (15%) patients (deaths = 270). High NT-pro BNP ratio was associated with higher risk of primary outcome in unadjusted (30.1 vs. 17.2 events/1000 person-year, hazard ratio or (HR) 1.73, 1.37-2.17, P < 0.001) and adjusted analysis (aHR 1.69, 95% 1.19-2.38, P = 0.003) vs. low NT-pro BNP ratio. Even in asymptomatic patients, NT-pro BNP ratio remained associated with primary outcome (aHR 1.28, 95% CI 1.06-1.54, P = 0.01).

Conclusions: Age-sex adjusted NT-pro BNP ratio is independently associated with long-term outcomes in oHCM patients, including in a subgroup of asymptomatic patients.