Cardiac Resynchronization Therapy Follow-up: Role of Remote Monitoring

Hemodynamic monitoring by intracardiac impedance measured by cardiac resynchronization defibrillators: Evaluation in a controlled clinical setting (BIO.Detect HF II study)

Background

In patients with cardiac resynchronization therapy defibrillators (CRT-Ds), intracardiac impedance measured by dedicated CRT-D software may be used to monitor hemodynamic changes. We investigated the relationship of hemodynamic parameters assessed by intracardiac impedance and by echocardiography in a controlled clinical setting.

Methods

The study enrolled 68 patients (mean age, 66 ± 9 years; 74% males) at 12 investigational sites. The patients had an indication for CRT-D implantation, New York Heart Association class II/III symptoms, left ventricular ejection fraction 15%–35%, and a QRS duration ≥150 ms. Two months after a CRT-D implantation, hemodynamic changes were provoked by overdrive pacing. Intracardiac impedance was recorded at rest and at four pacing rates ranging from 10 to 40 beats/min above the resting rate. In parallel, echocardiography measurements were performed. We hypothesized that a mean intra-individual correlation coefficient (r_mean) between stroke impedance (difference between end-systolic and end-diastolic intracardiac impedance) measured by CRT-D and the aortic velocity time integral (i.e., stroke volume) determined by echocardiography would be significantly larger than 0.65.

Results

The hypothesis was evaluated in 40 patients with complete data sets. The r_mean was 0.797, with a lower confidence interval bound of 0.709. The study hypothesis was met (p = 0.007). A stepwise reduction of stroke impedance and stroke volume was observed with increasing heart rate.

Conclusions

Intracardiac impedance measured by implanted CRT-Ds correlated well with the aortic velocity time integral (stroke volume) determined by echocardiography. The impedance measurements bear potential and are readily available technically, not requiring implantation of additional material beyond standard CRT-D system.

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Intracardiac impedance measurement feature (ICI-MF) is integrated in some CRT-Ds.

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We studied relationship between echo hemodynamic parameters and ICI-MF of CRT-Ds.

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Stroke volume by echo correlated well with stroke impedance by ICI-MF of CRT-Ds.

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Stepwise reduction in stroke impedance and stroke volume with increasing heart rate.

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The ICI-MF bears potential and requires only a ‘standard’ CRT-D system implantation.

Remote monitoring of implantable cardioverter-defibrillators and resynchronization devices to improve patient outcomes: dead end or way ahead?

Remote monitoring (RM) has become a new standard of care in the follow-up of patients with implantable pacemakers and defibrillators. While it has been consistently shown that RM enables earlier detection of clinically actionable events compared with traditional in-patient evaluation, this advantage did not translate into improved patient outcomes in clinical trials of RM except one study using daily multiparameter telemonitoring in heart failure (HF) patients. Therefore, this review, focusing on RM studies of implantable cardioverter-defibrillators and cardiac resynchronization therapy defibrillators in patients with HF, discusses possible explanations for the differences in trial outcomes. Patient selection may play an important role as more severe HF and concomitant atrial fibrillation have been associated with improved outcomes by RM. Furthermore, the technical set-up of RM may have an important impact as a higher level of connectivity with more frequent data transmission can be linked to better outcomes. Finally, there is growing evidence as to the need of effective algorithms ensuring a fast and well-structured clinical response to the events detected by RM. These factors re-emphasize the potential of remote management of device patients with HF and call for continued clinical research and technical development in the field.

Protocol-driven remote monitoring of cardiac resynchronization therapy as part of a heart failure disease management strategy

BACKGROUND

Cardiac resynchronisation therapy (CRT) is an established treatment for heart failure (HF) with reduced ejection fraction. CRT devices are equipped with remote monitoring functions, which are pivotal in the detection of device problems, but may also facilitate disease management. The aim of this study was to provide a comprehensive overview of the clinical interventions taken based on remote monitoring.

METHODS

This is a single centre observational study of consecutive CRT patients (n = 192) participating in protocol-driven remote follow-up. Incoming technical- and disease-related alerts were analysed together with subsequently triggered interventions.

RESULTS

During 34 ± 13 months of follow-up, 1372 alert-containing notifications were received (2.53 per patient-year of follow-up), comprising 1696 unique alerts (3.12 per patient-year of follow-up). In 60%, notifications resulted in a phone contact. Technical alerts constituted 8% of incoming alerts (0.23 per patient-year of follow-up). Rhythm (1.43 per patient-year of follow-up) and bioimpedance alerts (0.98 per patient-year of follow-up) were the most frequent disease-related alerts. Notifications included a rhythm alert in 39%, which triggered referral to the emergency room (4%), outpatient cardiology clinic (36%) or general practitioner (7%), or resulted in medication changes (13%). Sole bioimpedance notifications resulted in a telephone contact in 91%, which triggered outpatient evaluation in 8% versus medication changes in 10%. Clinical outcome was excellent with 97% 1-year survival.

CONCLUSIONS

Remote CRT follow-up resulted in 0.23 technical- versus 2.64 disease-related alerts annually. Rhythm and bioimpedance notifications constituted the majority of incoming notifications which triggered an actual intervention in 22% and 15% of cases, respectively.

Remote heart function monitoring: role of the CardioMEMS HF System

Heart failure is a pandemic condition that is challenging cardiology today. The primary economical and social burden of this syndrome is hospitalization rate whose costs represent the highest ones within the entire healthcare management. Remote monitoring of physiological data, obtained through self-reporting via telephone calls or, automatically, using external devices is a potential novel approach to implement management of patients with heart failure and reduce hospitalization rates. Relatively large but, sometimes, contradicting information exists about the efficacy of remote monitoring via different noninvasive approaches to reduce the economical and social burden of heart failure management. This leaves still partly unaddressed this critical issue and generates the need for new approaches. In this context, the CardioMEMS device that can chronically monitor pulmonary pressures from a small microchip inserted transvenously in the pulmonary artery seems to represent an innovative tool to challenge hospitalization rates. Consecutive analyses from the CHAMPION study had indeed documented the efficacy of the CardioMEMS in the remote monitoring of the pulmonary circulation status of patients with heart failure and in providing adequate information to optimally manage such patients with the final result of a significant hospitalization rate reduction. The striking information here is that this appears to be true in patients with preserved left ventricular ejection fraction also. Overall, the reports from the CHAMPION study encourage the use of CardioMEMS but larger populations are needed to definitively prove its value.