Preliminary experience with the multisensor HeartLogic algorithm for heart failure monitoring: a retrospective case series report

Abstract

Aims: In the Multisensor Chronic Evaluation in Ambulatory Heart Failure Patients study, a novel algorithm for heart failure (HF) monitoring was implemented. The HeartLogic (Boston Scientific) index combines data from multiple implantable cardioverter defibrillator (ICD)-based sensors and has proved to be a sensitive and timely predictor of impending HF decompensation. The remote monitoring of HF patients by means of HeartLogic has never been described in clinical practice. We report post-implantation data collected from sensors, the combined index, and their association with clinical events during follow-up in a group of patients who received a HeartLogic-enabled device in clinical practice.

Methods and results: Patients with ICD and cardiac resynchronization therapy ICD were remotely monitored. In December 2017, the HeartLogic feature was activated on the remote monitoring platform, and multiple ICD-based sensor data collected since device implantation were made available: HeartLogic index, heart rate, heart sounds, thoracic impedance, respiration, and activity. Their association with clinical events was retrospectively analysed. Data from 58 patients were analysed. During a mean follow-up of 5 ± 3 months, the HeartLogic index crossed the threshold value (set by default to 16) 24 times (over 24 person-years, 0.99 alerts/patient-year) in 16 patients. HeartLogic alerts preceded five HF hospitalizations and five unplanned in-office visits for HF. Symptoms or signs of HF were also reported at the time of five scheduled visits. The median early warning time and the time spent in alert were longer in the case of hospitalizations than in the case of minor events of clinical deterioration of HF. HeartLogic contributing sensors detected changes in heart sound amplitude (increased third sound and decreased first sound) in all cases of alerts. Patients with HeartLogic alerts during the observation period had higher New York Heart Association class (P = 0.025) and lower ejection fraction (P = 0.016) at the time of activation.

Conclusions: Our retrospective analysis indicates that the HeartLogic algorithm might be useful to detect gradual worsening of HF and to stratify risk of HF decompensation.

Keywords: CRT; Decompensation; Heart failure; ICD; Telemedicine.

Figure 1

A 65‐year‐old male with non‐ischaemic dilated cardiomyopathy, left bundle brunch block, and paroxysmal atrial fibrillation was implanted with a cardiac resynchronization therapy defibrillator in September 2017. After dismission, the patient was hospitalized again on 11 January 2018 (red line) for severe heart failure. At endovascular catheterization, an elevated left ventricular filling pressure was found. The retrospective HeartLogic index evaluation did show a previous number 16 crossing already on 2 November 2017 (blue line). Thus, an early warning for heart failure development did appear already 70 days before symptoms appearance that was mainly due to heart sounds (third, first) intensity modification. Patient died on 17 January 2018 despite resuscitation attempts.

Figure 2

A 74‐year‐old man with non‐ischaemic dilated cardiomyopathy, 22% ejection fraction, left bundle brunch block, and persistent atrial fibrillation was implanted with a cardiac resynchronization therapy defibrillator for primary prevention on May 2017 (Table 2, event 15). During follow‐up on 1 November 2017 (red line), he discontinued diuretic therapy. At a subsequent in‐office medical control on 4 December 2018, he reported weight gain of 4 kg within 7 days; therefore, diuretic therapy was restored (green line). HeartLogic index analysis showed crossing of the alarm threshold value already on 25 November 2017 (blue line) with thus an early warning 10 days in advance compared with clinical evaluation. That index normalized after therapy restoration. Main sensor contributing were heart sounds and thoracic impedance.

Figure 3

A 70‐year‐old man with ischaemic dilated cardiomyopathy, 30% ejection fraction, and permanent atrial fibrillation was implanted with a cardiac resynchronization therapy defibrillator for primary prevention in November 2017 (Table 2, event 8). In 20 December, the night heart rate was very high (122 b.p.m.); the rate persisted high (90/min) even in the following weeks. In 10 January 2018 at an outpatient routine control, the therapy was revisited in order to improve the rate control, thus allowing a better percentage of biventricular pacing. Night heart rate consequently lowered in the following days. On 15 January, patient reported rest dyspnoea (red line); therefore, on 25 January, diuretic dosages were increased (green line). Looking retrospectively to the HeartLogic index, we saw a value above 16 already on 31 December (blue line), thus giving a 15 day warning prior to symptoms. Contemporary to the night heart rate increment, there were also drops in S1 and S3 sound elevation. Index improved after potentiation of diuretics.

Figure 4

A 78‐year‐old man with ischaemic cardiomyopathy and 26% ejection fraction underwent a cardiac resynchronization therapy defibrillator implantation for primary prevention in December 2017 (Table 2, event 23). He complained of phrenic nerve stimulation‐related symptoms on 2 February 2018; therefore, the multi‐site ventricular stimulation was turned off. On 11 February, HeartLogic index crossed the 16 value (blue line). On 23 February at a subsequent in‐office control, a suitable new pacing stimulation mode was settled and the multi‐site pacing was restored (green line). As a consequence of a better ventricular stimulation setting, the index decreased to below 6. Heart sounds were the main contributing sensors.

Figure 5

A 70‐year‐old male with ischaemic heart disease, 26% ejection fraction, and persistent atrial fibrillation was implanted with a cardiac resynchronization therapy defibrillator for primary prevention in April 2017 (Table 2, event 12). At a scheduled medical control on 18 December, he reported worsening of heart failure symptoms (red line). The NT‐proBNP was very high (8619 pg/mL), and the diuretic dosages were increased. The patient was poorly compliant, and he modified the dosages only by the end of February 2018. HeartLogic index crossed the 16 value already on 1 November (blue line) that means 45 days before symptoms appearance. The long persistence of high values was possibly related to the delay in therapy adjustment. All heart sounds, thoracic impedance, respiratory rate, and night heart rate contributed to the HeartLogic index behaviour.