Abstract 4852: High Resting Velocity in Intramyocardial Coronary Artery is Related to Elevated Plasma Brain Natriuretic Peptide Levels in Patients With Hypertension

Abstract

Narrowings in intramyocardial coronary arteries (IMCA) and elevated plasma brain natriuretic peptide (BNP) levels have been demonstrated in hypertensive heart disease. To clarify the relation between abnormalities in IMCA and plasma BNP levels, 228 consecutive patients with hypertension were studied using high-frequency transthoracic Doppler echocardiography. We defined IMCA flow as abnormal one if acceleration flow in IMCA, indicating the presence of vessel narrowing, was detected by color flow mapping and the pulsed Doppler study demonstrated higher peak diastolic flow velocity than 32cm/sec (i.e. normal value + 2SD) in the site. Such abnormal flow in IMCA was demonstrated in 59 (56%) of 102 hypertensive patients with left ventricular hypertrophy (LVH) and in 36 (24%) of the other 126 hypertensive patients without LVH. Independent of LVH, the 95 hypertensive patients with abnormal IMCA flow had higher peak diastolic velocities in the IMCA (47.9±16.5 cm/s vs. 24.3±5.4 cm/s, p<0.01) and more elevated plasma BNP levels (131.0±24.4 pg/ml vs. 45.8±5.7 pg/ml, p<0.01) than those without abnormal IMCA flow. Furthermore, peak diastolic velocities had a significant correlation with log BNP values (p<0.01). The index of % area stenosis (IAS) estimated by the continuity equation was 46±14% at the site of acceleration flow, indicating the presence of mild to moderate lumen narrowing in the IMCA. The patients with the IAS of 50% and over had significantly higher log BNP values as compared to those with the IAS of less than 50% (p<0.05), indicating plasma BNP levels may be elevated by factors associated with lumen narrowing in the IMCA. Conclusions: High resting velocity in IMCA is at least partly related to elevated BNP levels in patients with hypertension independent of LVH.