A Device Histogram‐Based Simple Predictor of Mortality Risk in ICD and CRT‐D Patients: The Heart Rate Score

FIGURE 1. Effects of the device settings on the HrSc. Representative examples of the HrSc changes according to the device settings. The histograms show the baseline atrial sensed and paced histograms in the DDD mode with a lower rate limit (LRL) of 60 beats/min (bpm). (A) In this patient, with an increase in the LRL from 60 to 70 bpm, the HrSc increased from 42% to 80%. (B) In another patient, with the introduction of the rate‐response function, the HrSc decreased from 73% to 61%. These modifications are not rare in real‐world clinical practice. HrSc, heart rate score.

FIGURE 2. Study flow diagram. Of the 239 patients in the HINODE device cohort, HrSc data were missing at the initial device check in 56 patients (23.4%), resulting in a data acquisition success rate of 76.6%. After excluding patients with persistent AF and VVI mode, 172 patients comprised the baseline HrSc cohort. During the 2‐year follow‐up, 19 patients died, 1 switched to VVI mode, and 6 underwent device replacement. Final HrSc data were missing in only 4 (2.7%) of the remaining 146 patients, resulting in a remote data transmission success rate of 97.3%. Missing data were likely attributable to transmission failure or lack of remote monitoring connection. AF, atrial fibrillation; HrSc, heart rate score.

FIGURE 3. Kaplan–Meier curves. Kaplan–Meier survival curve analysis of the primary composite endpoint (A), all‐cause death (B), and HF events (C). HF, heart failure; HrSc, heart rate score.

FIGURE 4. Impact of baseline HrSc ≥ 70% on the primary endpoint in specific subgroups. CRT, cardiac resynchronization therapy; HrSc, heart rate score; ICD, implantable cardioverter defibrillator; ICM, ischemic cardiomyopathy; LRL, lower rate limit; LVEF, left ventricular ejection fraction; othoracic ratio; NICM, non‐ischemic cardiomyopathy; PM, pacemaker.

FIGURE 5. Temporal changes in the HrSc. (A) Individual patient data comparing the baseline and last HrSc, with the p‐value calculated using the paired t‐test. (B) Categorized classification. HrSc, heart rate score.