359 - Case Study: Changes in Respiratory Rate, Third Heart Sound, and HeartLogic Identify Worsening Heart Failure in a Patient with no Decrease in Impedance

Introduction: Clinical signs of an impending heart failure event (HFE) can be detected by implantable devices via transthoracic impedance (TI), respiratory rate (RR), and third heart sound (S3). An increase in RR and S3, as well as a decrease in TI can individually or collectively indicate HFE. However, impedance data in the first 3 to 6 months post implant is susceptible to upward drift due to maturation of the system which can mask the decrease. In contrast, RR and S3 data are not affected by system maturation. The HeartLogic multi-sensor algorithm combines signals from multiple sensors including TI, RR, S3, heart rate, and patient activity, and thus can be more robust than single-sensor algorithms. We report a case where an HFE within 6 months post implant is preceded by a HeartLogic alert with a clear increase in RR and S3 but no decrease on the TI trend. Methods: The MultiSENSE trial enrolled 900 patients implanted with COGNIS CRT-D devices and followed them up to 1 year. Device software was modified to permit collection of chronic diagnostic sensor data including RR, S3, and TI. Adverse events were independently adjudicated to identify HFEs defined as HF admissions or unscheduled visits with intravenous HF treatment. Case report: A 50-year-old Hispanic male (163 cm, 94.8 kg, ischemic dilated cardiomyopathy, previous smoker, hypertension, and hyperlipidaemia) was implanted with a CRT-D in September of 2011 and was enrolled in October of the same year. On day 138 post implant he was admitted for shortness of breath, orthopnoea, and weight gain. He reported not taking his medications for a week prior to hospitalization and ingesting excessive quantities of alcohol and salty foods. He was treated with IV bumetanide and spironolactone and discharged 2 days later. The figure shows daily TI, RR, and S3 trends along with 3-day moving averages; the bottom graph shows daily HeartLogic values and its alert threshold. The TI trend does not show any decline and instead continues to increase throughout all 3 months of trending. The RR and S3 trends show a significant increase in the month preceding the event. HeartLogic crossed the alert threshold on day 66 post implant, 73 days before the HFE. Conclusion: In this case HeartLogic, RR, and S3 provided a strong signal for HFE, but TI trend was falsely negative for HFE, masked in the upward drift following implant. This example illustrates the benefits of following more than one sensor to detect HFEs.