Is the median hourly ambulatory heart rate range helpful in stratifying mortality risk among newly diagnosed atrial fibrillation patients?

Background: The application of heart rate variability is problematic in patients with atrial fibrillation (AF). This study aims to explore the associations between all-cause mortality and the median hourly ambulatory heart rate range (ÃHRR_24hr) compared with other parameters obtained from the Holter monitor in patients with newly diagnosed AF. Material and Methods: A total of 30 parameters obtained from 521 persistent AF patients’ Holter monitor were analyzed retrospectively from 1 January 2010 to 31 July 2014. Every patient was followed up to the occurrence of death or the end of 30 June 2017. Results: ÃHRR_24hr was the most feasible Holter parameter. Lower ÃHRR_24hr was associated with increased risk of all-cause mortality (adjusted hazard ratio [aHR] for every 10-bpm reduction: 2.70, 95% confidence interval [CI]: 1.75–4.17, p < 0.001). The C-statistic of ÃHRR_24hr alone was 0.707 (95% CI: 0.658–0.756), and 0.697 (95% CI: 0.650–0.744) for the CHA2DS2-VASc score alone. By combining ÃHRR_24hr with the CHA2DS2-VASc score, the C-statistic could improve to 0.764 (95% CI: 0.722–0.806). While using 20 bpm as the cut-off value, the aHR was 3.66 (95% CI: 2.05–6.52) for patients with ÃHRR_24hr < 20 bpm in contrast to patients with ÃHRR_24hr ≥ 20 bpm. Conclusions: ÃHRR_24hr could be helpful for risk stratification for AF in addition to the CHA2DS2-VASc score.