Abstract 4928: Coronary Flow Reserve is Reduced in Pulmonary Arterial Hypertension Patients
Background: Pump function of the right ventricle, which is a major determinant of prognosis in pulmonary arterial hypertension (PAH), is much influenced by coronary perfusion. Acute studies in animals exhibited paradoxical coronary flow decrease under excessive pressure overload. However, little is known about human or chronic coronary flow reserve (CFR) in PAH.
Methods: Coronary flow measurement with pulse Doppler was performed for 19 PAH consecutive patients (right ventricular systolic pressure RVSP 89.7±22.7 mmHg; age 22.0±5.5 year; 10 females, data are mean±SD). The control state blood velocity was recorded in distal right coronary artery (RCA). The maximal blood velocity was recorded at the same site, on continuous infusion of adenosine triphosphate (150ng/kg/min). CFR was defined as the ratio of peak adenosine/baseline flow velocity. RVSP was adopted from the most adjacent catheterization. Coronary arterial lesions were excluded with coronary angiogram.
Results: RCA flow signals were achieved in 17/19. Systolic flow signals were observed in 2/17. RCA diastolic peak velocity in basal condition was somewhat higher than reported in normal subjects (29.9±11.4 cm/sec) and positively correlated with right ventricular systolic pressure (RVSP) with significance (R^2 = .236; p<0.05). CFR of RCA ranged 1.55– 4.16 (2.46±0.82) and was below 2.0 in 7/17. It negatively correlated with RVSP (R^2 = .383; P < 0.01).
Conclusion: Peak flow velocity of RCA in PAH correlated with RVSP, in reply to greater energy demand of RV. CFR of RCA was low and negatively correlated with RVSP, which may suggest poor energy supply reserve in PAH patients.