Comparison of HeartLogic Heart Failure Diagnostic Sensor Measurements and Alerts between Patients with CRT-D and ICD Devices

Abstract

Background HeartLogic®, a device-based heart failure (HF) composite index and alert algorithm, aggregates physiologic trends associated with multiple aspects of HF status (e.g. heart sounds, heart rate, thoracic impedance, respiration rate, tidal volume, and activity). The MultiSENSE study showed that HeartLogic alerts predict HF events with high sensitivity. However, it is unknown if alerts differ by type of device (CRT-D vs ICD). Objective To compare HF sensor measurements and alerts between patients with CRT-D and ICD devices with HeartLogic capability. Methods The ALTITUDE database collects de-identified data recorded by the implanted devices from the LATITUDE remote monitoring system. US patients with HeartLogic compatible devices with a minimum of 90 days of daily sensor data were included. HeartLogic alerts for each patient were identified when the daily HeartLogic index value crossed the nominal alert threshold of 16. The observed alert rate was calculated as the total number of alerts divided by the total patient follow-up years. 95% confidence intervals were calculated using a generalized linear model with a log link and a negative binomial distribution. Sensor measurement comparisons were performed using Student's t-test and an alpha level of 0.0001 due to the large sample size. Results Out of 11576 US patients in ALTITUDE, 7633 (4583 CRT-D and 3050 ICD patients) contained sensor data over 90 days with an average follow-up period of 221±94.39 days (median [25th, 75th percentile] = 207 [142,286] days). Despite differences in some individual sensors (Heart Sound S1, Thoracic Impedance, Time Active) (Table 1), HeartLogic alert rates (Fig 1) were not significantly different between CRT-D and ICD (CRT-D: 1.71 (95% CI 1.67, 1.78), ICD: 1.64 (1.58, 1.73), p = 0.11). Furthermore, the real-world HeartLogic alert rates of both CRT-D and ICD patients were similar to the MultiSENSE study alert rate of 1.65 (1.50, 1.88) (CRT-D: p = 0.44 and ICD: p = 0.92). Conclusion Real-world HeartLogic alert rates did not differ between CRT-D and ICD recipients, and were similar to the MultiSENSE study, despite some differences in individual sensor measurements. Further investigation is needed to understand whether these differences relate to severity of HF or impact the predictive utility of HeartLogic for HF events.