We investigated the acute effect of orally administered high-dose folic acid on coronary dilator function in humans.
Background
Folic acid and its active metabolite, 5-methyltetrahydrofolate, increase endothelium-dependent vasodilation in human peripheral circulation. However, the acute effect on coronary circulation is not known.
Methods
Fourteen patients with ischemic heart disease, age 62 ± 12 years (mean ± SD), were enrolled in a double-blind, placebo-controlled crossover trial. Basal and adenosine-stimulated myocardial blood flow (MBF) were determined by positron emission tomography, and myocardial flow reserve was calculated. Each patient was studied after ingestion of placebo and after ingestion of 30 mg folic acid. Myocardial zones were prospectively defined physiologically as “normal” versus “abnormal” on the basis of MBF response to adenosine 140 μg/kg/min (normal = MBF >1.65 ml/min/g). Abnormal and normal zones were analyzed separately in a patient-based analysis.
Results
Folate was associated with a reduction in mean arterial pressure (100 ± 12 mm Hg vs. 96 ± 11 mm Hg, placebo vs. folate, p < 0.03). Despite the fall in mean arterial pressure, folic acid significantly increased the MBF dose response to adenosine (p < 0.001 using analysis of variance) in abnormal zones, whereas MBF in normal zones did not change. In abnormal segments, folic acid increased peak MBF by 49% (1.45 ± 0.59 ml/min/g vs. 2.16 ± 1.01 ml/min/g, p < 0.02). Furthermore, folate increased dilator reserve by 83% in abnormal segments (0.77 ± 0.59 vs. ml/min/g 1.41 ± 1.08 ml/min/g, placebo vs. folate, p < 0.05), whereas dilator reserve in normal segments remained unchanged (2.00 ± 0.61 ml/min/g vs. 2.12 ± 0.69 ml/min/g, placebo vs. folate, p = NS).
Conclusions
The data demonstrate that high-dose oral folate acutely lowers blood pressure and enhances coronary dilation in patients with coronary artery disease.
Abbreviations and acronyms
Ado 140
adenosine 140 μg/kg/min
MBF
myocardial blood flow
PET
positron emission tomography
Cited by (0)
This study was supported, in part, by grants from the National Institutes of Health (RR16046) (to Dr. Tawakol) and the American Society of Nuclear Cardiology (to Dr. Tawakol).
