Increased plasma brain natriuretic peptide level as a guide for silent myocardial ischemia in patients with non-obstructive hypertrophic cardiomyopathy

Objectives We measured plasma atrial/brain natriuretic peptide (ANP/BNP) levels at rest and during exercise and correlated the results with various clinical findings, particularly with myocardial ischemia, in asymptomatic hypertrophic cardiomyopathy (HCM). Background In patients with HCM, ANP and BNP levels are elevated and exercise-induced myocardial ischemia is common. However, it has not yet been elucidated how these levels at rest and their change with dynamic exercise are related to ischemia. Methods Levels of ANP and BNP were measured at rest and at peak exercise during 99mTc-tetrofosmin scintigraphy in 31 asymptomatic patients with non-obstructive HCM and in 10 control subjects. Results Levels of ANP and BNP at rest and the change of ANP and BNP levels (pg/ml) from rest to exercise were significantly greater in HCM than in control subjects (ANP: rest, 53.2 ± 31.8 vs. 11.6 ± 6.1; exercise, 114.5 ± 74.8 vs. 28.3 ± 23.4. BNP: rest, 156.7 ± 104.1 vs. 9.8 ± 9.6; exercise, 201.6 ± 131.5 vs. 13.2 ± 14.5). Septal perforator compression (SPC) and exercise-induced ischemia were observed, respectively, in 20 (64.5%) and in 19 (61.3%) patients with HCM. The increment of ANP during exercise was similar between HCM subgroups with or without inducible ischemia. However, BNP levels at rest and BNP increments during exercise were significantly greater in the HCM subgroup with inducible ischemia than in the subgroup without (rest, 190.5 ± 116.2 vs. 103.1 ± 48.3; exercise, 250.5 ± 142.2 vs. 124.2 ± 58.6). Multiple logistic regression analysis revealed that SPC and BNP levels at rest were independently associated with exercise-induced ischemia. Conclusions Measurement of plasma BNP levels at rest may be useful in predicting silent myocardial ischemia in HCM.