Early Detection of Subclinical Worsening Heart Failure Using a Respiratory Stability Telemonitoring System

BACKGROUND: Early detection of subclinical worsening heart failure (HF) is essential to enable timely, proactive treatment that may alter the clinical course and prevent hospitalization. This study demonstrates how early non-invasive telemonitoring of respiratory stability time (RST) can detect subclinical worsening HF. METHODS AND RESULTS: Daily RST was calculated automatically from all-night respiratory signals in 66 patients. Subclinical worsening was detected by declines in RST preceding overt worsening HF in the control group (blinded to RST; n=35) and in the RST group (RST monitored daily by clinicians; n=31). The RST recovery zone sufficient to avert hospitalization was determined by RST responses to treatment escalation for overt worsening HF. Two clinically relevant RST thresholds were identified: RST <20 s, indicating a high-risk zone for subclinical worsening preceding hospitalization; and RST ≥30 s, defining a recovery target zone associated with hospitalization avoidance. The duration of subclinical worsening HF from the onset of RST decline <20 s to overt worsening was 40.0 days in the control group. In contrast, the interval from the onset of overt worsening HF to hospitalization was markedly shorter (control group, 7.5 days; RST group, 8.0 days). CONCLUSIONS: Noninvasive RST telemonitoring enables early detection of the prolonged subclinical worsening phase of HF and provides a clinically actionable biological target for proactive intervention aimed at preventing HF-related hospitalization.