Abstract 11820: Importance of Resting Heart Rate Assessment in Autonomic Dysfunction Evaluation in Congestive Heart Failure Patients

Abstract

Background: Novel treatments in congestive heart failure (CHF) aim at ameliorating autonomic dysfunction. Autonomic dysfunction typically manifests with resting tachycardia and blunted baroreceptor reflex response and been classically described in CHF with reduced LV ejection fraction (EF) but baroreflex function in CHF with preserved EF has not been well investigated. Methods: A single center prospective study was conducted by measuring resting and lowest heart rates (HR) during voluntary breath holding in 118 CHF patients, 68 ± 14 years old, 50 females (42.3%), BMI 30.1 ± 8.5 kg/m 2 , HTN in 97 (82.2%), CAD in 64 (54.2%), diabetes in 49 (41.5%), and chronic lung disease in 39 patients (33.1%). HFrEF less than 40% was found in 41 (34.7%) patients; for the purposes of analysis HRmrEF and HFpEF groups were combined. Beta-blockers were used in 92 (78%) and non-dihydropyridine calcium channel blockers were used in 7 (5.9%) patients. Results: The majority of HFpEF or HFmrEF patients had resting HR less than 80 bpm (55/77 patients, 71.4%), while the majority of HFrEF patients had resting HR more than 70 bpm (32/41 patients, 78%, p=0.015). Furthermore, HFpEF and HFmrEF patients had lower breath holding HR (69.7 ± 14.7 bpm in HFpEF and HFmrEF patients vs. 77.6 ± 13.9 bpm in HFrEF patients, p=0.005). There was a trend of increased resting HR in patients with Class IV CHF (p=0.179). Furthermore, class IV CHF patients manifested with increased breath holding HR (68.9 ± 15.3 bpm in combined NYHA class I-II, 69.9 ± 12.2 bpm in NYHA class III, 79.9 ± 16.1 bpm in NYHA class IV, p=0.02). Regardless of the CHF class (p=0.060) and/or LV EF (p=0.913), increased resting HR was associated with higher breath holding HR. Patients with baseline HR <60 bpm had breath holding HR of 54.6 ± 6.2 bpm, as compared to 94.9 ± 9.0 bpm in patients with baseline HR >90 bpm, p<0.001. Conclusion: In CHF patients, increased resting HR is a strong indicator of abnormal baroreceptor function. HRmrEF and HFpEF patients have lower resting and breath holding HR, suggesting less pronounced autonomic dysfunction, as compared to more pronounced autonomic dysfunction in HFrEF patients. Additional studies are needed to investigate whether autonomic modulation treatment is equally beneficial in patients across the LVEF spectrum.