Introduction: In post-discharge acute heart failure (HF) patients, physicians aim to up titrate HF medication to alleviate HF symptoms and prolong survival. Previous studies have shown the usefulness of cardiac acoustic biomarkers (CABs - acoustic cardiography synchronized with ECG) in the early detection of HF decompensation. The primary goal of this study was to assess CAB variations in patients with HF with reduced ejection fraction (HFrEF) with and without changes to their HF medication.

Methods: Patients with HFrEF were fitted with the wearable cardioverter defibrillator (WCD; ZOLL LifeVest^®, USA) in an outpatient setting after acute hospitalization for HF decompensation for primary prevention of SCD   in a prospective observational study (ClinicalTrials.gov Identifier: NCT03203629). The WCD was also able to record CAB continuously during use. Weekly phone calls were used to collect changes to HF medication. A previously developed multivariate model of CABs (CAB model) based on heart rate, electromechanical activation time (QRS onset to S1), and S3 strength (formulated from S3 timing, intensity, persistence, and frequency) was used to classify the study patients as high or low risk for HF decompensation. Chi-square test was used to compare patients with and without HF medication changes (β-blockers, ACEi/ARB/ARNi, diuretics) and CABs based risk of HF decompensation at the beginning and end of WCD use.

Results: Of the 627 patients (mean age: 61±13 years; 77% male; BMI: 28±6 kg/m²; Ischemic HF: 38%) 94% were prescribed beta blockers at begin of WCD use, whilst 88% of the patients were started on ACEi/ARB/ARNi and 84% on diuretics. A total of 207 pts (33%) had at least one change to their HF medication during their WCD use (median wear time: 83 days; IQR 46 days). For this subgroup, 24% of the patients were classified as being at high risk for HF decompensation by the CAB model at beginning of WCD use compared to 14% at the end of WCD use (p = 0.01). In contrast, for those with no HF medication changes (n = 420), 15% were classified as high risk by the CAB model at the beginning of WCD use compared to 11% at the end of WCD use (p = n. s.).  

Conclusions: In this study population of HFrEF patients, there was a high prescription rate of beta blockers, RAAS-inhibitors, diuretics at begin of WCD use for primary prevention of SCD. The CAB model for HF decompensation showed a greater decrease in the percentage of patients estimated to be at high risk for a HF event at the end of WCD use in the group that received HF medication changes compared to the group without these  medication changes. Thus, CABs may reflect effective titration of HF medication overtime.