OBJECTIVES: The intention of this study was to test the hypothesis that, in heart failure patients, dietary supplementation of polyunsaturated fatty acids (PUFA) enhances arterial baroreceptor control of the cardiovascular system.

BACKGROUND: Administration of PUFA reduces the risk of life-threatening arrhythmias in patients surviving myocardial infarction.
This might result from potentiation of arterial baroreflexes, but whether or not PUFA enhance baroreflex function has never been studied in humans.

METHODS: Patients with post-myocardial infarction left ventricular dysfunction underwent beat-to-beat blood pressure (BP) (Finapres, Ohmeda Inc., Englewood, Colorado) and R-R interval (electrocardiogram) recording;
baroreceptor reflexes were assessed from the bradycardic and depressor responses to graded neck suction (NS) as well as by computation of the alpha "spontaneous" baroreflex sensitivity index. Assessments were repeated after prolonged treatment with PUFA (2 g/die, n = 15) or placebo (n = 10).

RESULTS: Baseline BP and R-R interval were unaffected by PUFA. Both reflex depressor and bradycardic responses to NS increased after PUFA (respectively from -0.09 +/- 0.01 to -0.16 +/- 0.01 mm Hg x mm Hg(-1), p < 0.01, and from 1.25 +/- 0.9 to 1.76 +/- 1.1 ms x mm Hg(-1), p < 0.04) but not after placebo. The spontaneous baroreflex sensitivity increased in the PUFA (from 8.99 +/- 1.4 to 12.2 +/- 1.2 ms x mm Hg(-1), p < 0.02) but not in the placebo group. Polyunsaturated fatty acids (but not placebo) treatment also significantly increased R-R interval total variance and low-frequency and high-frequency spectral powers.
CONCLUSIONS: Dietary PUFA supplementation markedly potentiates baroreflex function and enhances heart rate variability in patients with stable congestive heart failure.