ARTERIAL BAROREFLEX MODULATION OF HEART-RATE IN CHRONIC HEART-FAILURE- CLINICAL AND HEMODYNAMIC CORRELATES AND PROGNOSTIC IMPLICATIONS

Background In chronic heart failure (CHF), arterial baroreflex regulat ion of cardiac function is impaired, leading to a reduction in the ton ic restraining influence on the sympathetic nervous system. Because ba roreflex sensitivity (BRS), as assessed by the phenylephrine technique , significantly contributes to postinfarction risk stratification, the aim of the present study was to evaluate whether in CHF patients a de pressed BRS is associated with a worse clinical hemodynamic status and unfavorable outcome. Methods and Results BRS was assessed in 282 CHF patients in sinus rhythm receiving stable medical therapy (age, 52 +/- 9 years; New York Heart Association [NYHA] class, 2.4 +/- 0.6; left v entricular ejection fraction [LVEF], 23 +/- 6%). The BRS of the entire population averaged 3.9 +/- 4.0 ms/mm Hg (mean +/- SD) and was signif icantly related to LVEF and hemodynamic parameters (LVEF, P < .005; ca rdiac index and pulmonary wedge pressure, P < .001 by regression analy sis), Patients ill NYHA classes III or IV and those with severe mitral regurgitation had markedly depressed vagal reflexes, The association of BRS with survival was described after its categorization in three g roups: below the lowest quartile (< 1.3 ms/mm Hg), between the lowest quartile and the median (1.3 to 3 ms/mm Hg), and above the median (> 3 ms/mm Hg). During a mean follow-up of 15 +/- 12 months, 78 primary ev ents (cardiac death, nonfatal cardiac arrest, and status 1 priority tr ansplantation) occurred (27.6%). BRS was significantly related to outc ome (log rank, 9.1; P < .01), with a relative risk of 2.7 (95% confide nce interval, 1.6 to 4.7) for patients with the major derangement in B RS (< 1.3 ms/mm Hg), At multivariate analysis, BRS was an independent predictor of death after adjustment for noninvasive known risk factors but not when hemodynamic indexes were also considered. In CHF patient s with severe mitral regurgitation, however, BRS remained a strong pro gnostic marker independent of hemodynamic function. Conclusions In mod erate to severe CHF, a depressed sensitivity of vagal reflexes paralle ls the deterioration of clinical and hemodynamic status and is signifi cantly associated with poor survival. Particularly in patients with se vere mitral regurgitation the baroreceptor modulation of heart rate pr ovides prognostic information of incremental value to hemodynamic para meters.