Exercise Training Restores Sympathetic Response during Exercise in Patients with Acute Coronary Syndrome and Gln27Glu β 2 ‐adrenoceptor Polymorphism

Abstract

We tested the hypothesis that patients with acute coronary syndrome (ACS) homozygous for the C allele of the β2-adrenoceptor polymorphism (Gln27Gln-CC) would have increased muscle sympathetic nerve activity (MSNA) response during exercise compared to patients carrying the G allele (Gln27Glu-CG and Glu27Glu-GG). In addition, exercise training would restore this response in CC patients.Thirty-days after ischemic event, 61 patients without ventricular dysfunction were divided into two groups: 1) CC and 2) CG+GG. From these patients, twenty-five underwent to exercise training for 8 weeks (CC, n=17; CG+GG, n=8). MSNA (microneurography) and blood pressure (BP, oscillometric device) were measured at rest and during 3-min of handgrip exercise (30% maximal voluntary contraction). At baseline, MSNA (P=0.03) and BP (P=0.04) responses during exercise were higher in CC group when compared to CG+GG. Exercise training significantly decreased MSNA response during exercise in CC group (Δ=12±2 vs. 5±2bursts/100HB, P=0.02), but not in CG+GG group (Δ=7±3 vs. 7±3bursts/100HB, P=0.96). The BP did not change after training in both groups. We conclude that patients with ACS homozygous for the C allele of the β2-adrenoceptor polymorphism have increased MSNA response during exercise. Importantly, exercise training reverts the exaggerated MSNA response in CC patients. These findings strength the idea that exercise training should be recommended to patients with ACS, especially those homozygous for the C allele of the β2-adrenoceptor polymorphism (Gln27Gln-CC). Funding: FAPESP and CNPq