Abstract 13656: Effects of Left Ventricular Ejection Fraction and NYHA CHF Class on Baroreceptor Function in Congestive Heart Failure

Abstract

Background: Autonomic dysfunction is an important component in congestive heart failure (CHF) pathophysiology. The combined effects of reduced ejection fraction and advanced CHF Class on baroreceptor function in CHF have not been well investigated. Methods: A single center prospective study included 118 consenting patients, 68.3 ± 14.2 years old, 50 females (42.3%), BMI of 30.1 ± 8.5 kg/m 2 , with histories of HTN in 97 (82.2%), CAD in 64 (54.2%), diabetes in 49 (41.5%), and COPD or asthma in 39 (33.1%). Class I or II CHF were documented in 32 (27.1%), class III in 53 (44.9%), and class IV in 33 (28%) patients. Mean LV EF was 44.5+/-13.9%, HFrEF was present in 41 (34.7%) patients. Baroreceptor function was assessed by measuring resting and lowest heart rates (HR) during voluntary breath holding. Results: Despite treatment with beta-adrenergic blockers in 92 (78%) and non-dihydropyridine calcium channel blockers in 7 (5.9%) patients, increased CHF class was associated with significantly increased resting (71.7 ± 14.4 bpm in Class I-II, 73.1 ± 13.6 bpm in Class III, and 80.8 ± 16.9 bpm in Class IV, p=0.027) and breath holding HR (68.9 ± 15.3 bpm in Class I-II, 69.9 ± 12.2 bpm in Class III, and 80 ± 16.1 bpm in Class IV, p=0.002). In addition, when compared to the rest of the cohort, HFrEF patients manifested with increased resting (80.9 ± 14.5 vs. 71.6 ± 14.6 bpm, p=0.001) and breath holding HR (77.6 ± 13.9 vs. 69.7 ± 14.7 bpm, p=0.006). In multivariate analysis, both increased CHF NYHA class and reduced LVEF retained statistically significant independent effects on resting (p=0.037 and p=0.001, respectively) and breath holding HR (p=0.005, each). Conclusion: Decreased LV ejection fraction and increased CHF class independently and significantly contribute to autonomic dysfunction in CHF patients. Heart rate changes indicating abnormal baroreceptor function in CHF patients are apparent despite treatment with medications affecting chronotropic response.