Baroreflex sensitivity in asymptomatic coronary atherosclerosis
Sakari Simula, Department of Neurology, Mikkeli Central Hospital, Porrassalmenkatu 35-37, 50100 Mikkeli, Finland
Baroreflex sensitivity (BRS) reflects the effectiveness of cardiac parasympathetic regulation. BRS becomes impaired in stable coronary artery disease (CAD) and after myocardial infarction and carries prognostic information in these patients. Whether impaired BRS is found already in asymptomatic subjects, with subclinical coronary atherosclerosis, has remained elusive.
The relationship between BRS and coronary atherosclerosis was evaluated in 31 subjects with high familial risk for CAD but without evidence of angina pectoris or myocardial ischaemia. Single photon emission tomography was performed with 99mTc-sestamibi to rule out myocardial perfusion defects at rest and during exercise. BRS was assessed by phenylephrine technique. Coronary atherosclerosis was analysed by quantitative coronary angiography (QCA). Percentage of diameter stenosis (PDS) was calculated separately for LAD, LCX, RCA coronary arteries as well as for proximal (PROX), middle (MID) and distal (DIST) coronary artery regions; and for all coronary artery regions (global PDS).
Baroreflex sensitivity averaged 7·8 ± 5·4 ms mmHg−1. BRS showed inverse correlation to PDS of the proximal coronary artery segments (r = −0·315; P<0·05) and with the most severe single coronary artery stenosis (r = −0·374; P<0·05). Five (16%) subjects had BRS ≤ 3 ms mmHg−1. They had more severe PDS of proximal coronary artery segment than subjects with BRS > 3 ms mmHg−1 (24 ± 7% versus 13 ± 11%, P<0·05, respectively).
Impairment of BRS was found to be associated with the severity of subclinical coronary atherosclerosis in healthy asymptomatic subjects with familial risk of CAD. Asymptomatic subjects with severely blunted BRS may have advanced coronary atherosclerosis.