Economic implications of adding a novel algorithm to optimize cardiac resynchronization therapy: rationale and design of economic analysis for the AdaptResponse trial

AIMS

Although cardiac resynchronization therapy (CRT) has proven beneficial in several randomized trials, a subset of patients have limited clinical improvement. The AdaptivCRT algorithm provides automated selection between synchronized left ventricular or biventricular pacing with optimization of atrioventricular delays. The rationale and design of the economic analysis of the AdaptResponse clinical trial are described.

RATIONALE

The costs associated with HF hospitalization are substantial and are compounded by a high rate of readmission. HF hospitalization payments range from $1,001 for Greece to $12,235 for US private insurance. When examining the breakdown of HF-related costs, it is clear that approximately 55% of the hospitalization costs are directly attributable to length of stay. Notably, the mean costs of a CRT patient in need of a HF-related hospitalization are currently estimated to be an average of $10,679.

METHODS

The economic analysis of the AdaptResponse trial has two main objectives. The hospital provider objective seeks to test the hypothesis that AdaptivCRT reduces the incidence of all-cause re-admissions after a heart failure admission within 30 days of the index event. A negative binomial regression model will be used to estimate and compare the number of readmissions after an index HF hospitalization. The payer economic objective will assess cost-effectiveness of CRT devices with the AdaptivCRT algorithm relative to traditional CRT programming. This analysis will be conducted from a U.S. payer perspective. A decision analytic model comprised of a 6-month decision tree and a Markov model for long term extrapolation will be used to evaluate lifetime costs and benefits.

CONCLUSION

AdaptivCRT may offer improvements over traditional device programming in patient outcomes. How the data from AdaptResponse will be used to demonstrate if these clinical benefits translate into substantial economic gains is herein described.

Differences in clinical characteristics and reported quality of life of men and women undergoing cardiac resynchronization therapy

Aims

Response to cardiac resynchronization therapy (CRT) is known to be associated with a number of clinical characteristics, including QRS duration and morphology, gender, height, and the aetiology of heart failure (HF). We assessed the relation of gender and baseline characteristics with QRS duration and Kansas City Cardiomyopathy Questionnaire.

Methods and results

AdaptResponse is a global randomized trial. The trial enrolled CRT‐indicated patients with New York Heart Association classes II–IV HF, left bundle branch block (QRS ≥ 140 ms in men, ≥130 ms in women), and baseline PR interval ≤200 ms. In total, 3620 patients were randomized, including 1569 women (43.3%) approaching the actual proportion of women in the HF population. Women were older and more often New York Heart Association class III or IV than men (55.6% vs. 48.7%), had less frequent ischaemic cardiomyopathy (21.2% vs. 39.5%), and had a 5.1 ms shorter QRS duration than men. Women were more often depressed (18.5% vs. 9.7%), had a significantly lower Kansas City Cardiomyopathy Questionnaire score, and had differences in medication prescriptions.

Conclusions

AdaptResponse is the largest randomized CRT trial and enrolled more women than any other landmark CRT trial. Women differed from men with regard to baseline characteristics and quality of life. Whether these differences translate into clinical outcome differences will be examined further in the AdaptResponse trial.

Real-world behavior of CRT pacing using the AdaptivCRT algorithm on patient outcomes: Effect on mortality and atrial fibrillation incidence

Background

The AdaptivCRT (aCRT) algorithm continuously adjusts cardiac resynchronization therapy (CRT) according to intrinsic atrioventricular conduction, providing synchronized left ventricular pacing in patients with normal PR interval and adaptive BiV pacing in patients with prolonged PR interval. Previous analyses demonstrated an association between aCRT and clinical benefit. We evaluated the incidence of patient mortality and atrial fibrillation (AF) with aCRT compared with standard CRT in a real‐world population.

Methods and Results

Patients enrolled in the Medtronic Personalized CRT Registry and implanted with a CRT from 2013‐2018 were divided into aCRT ON or standard CRT groups based upon device‐stored data. A Frailty survival model was used to evaluate the potential survival benefit of aCRT, accounting for patient heterogeneity and center variability. Daily AF burden and first device‐detected AF episodes of various durations were recorded by the device during follow‐up.

A total of 1814 CRT patients with no reported long‐standing AF history at implant were included. Mean follow‐up time was 26.1 ± 16.5 months and 1162 patients (64.1%) had aCRT ON. Patient survival probability at 36 months was 88.3% for aCRT ON and 83.7% for standard CRT (covariate‐adjusted hazard ratio [HR] = 0.71, 95% CI: 0.53‐0.96, P = .028). Mean AF burden during follow‐up was consistently lower in aCRT ON patients compared with standard CRT. At 36 months, the probability of AF was lower in patients with aCRT ON, regardless of which AF definition threshold was applied (6 minutes‐30 days, all P < .001).

Conclusion

Use of the AdaptivCRT algorithm was associated with improved patient survival and lower incidence of AF in a real‐world, prospective, nonrandomized registry.

Field dynamics in atrioventricular activation. Clinical evidence of a specific field-to-protein interaction

The atrioventricular node (AV) is considered the electrical connection between the atria and ventricles. There is an electrical pause between activation of the atria and the ventricles (PR segment), but to date the mechanism responsible for this interruption remains unclear. The present communication focuses on the hypothesis that magnetic field dynamics could provide the answer. Proof of this hypothesis is that in Wolff-Parkinson-White syndrome, where there is physical connection between the atria and ventricles (bundle of Kent), there is electrical AV continuity, no PR segment is detected, and catheter ablation of the abnormal bundle restores AV discontinuity. Spontaneous initiation of the heart at the level of the sinus node, the pacemaker of the heart, could also be explained via field dynamics. The known transmembrane pacemaker protein CHN4, present in both sinoatrial and AV nodal cells, could interact with field information to provide specificity in an electronic key-to-lock mechanism interaction.

Pacsin 2 is required for the maintenance of a normal cardiac function in the developing mouse heart

The Pacsin proteins (Pacsin 1, 2 and 3) play an important role in intracellular trafficking and thereby signal transduction in many cells types. This study was designed to examine the role of Pacsin 2 in cardiac development and function. We investigated the development and electrophysiological properties of Pacsin 2 knockout (P2KO) hearts and single cardiomyocytes isolated from 11.5 and 15.5days old fetal mice. Immunofluorescence experiments confirmed the lack of Pacsin 2 protein expression in P2KO cardiac myocytes in comparison to wildtype (WT). Western blotting demonstrates low expression levels of connexin 43 and T-box 3 proteins in P2KO compared to wildtype (WT). Electrophysiology measurements including online Multi-Electrode Array (MEA) based field potential (FP) recordings on isolated whole heart of P2KO mice showed a prolonged AV-conduction time. Patch clamp measurements of P2KO cardiomyocytes revealed differences in action potential (AP) parameters and decreased pacemaker funny channel (I_f), as well as L-type Ca²⁺ channel (I_CaL), and sodium channel (I_Na). These findings demonstrate that Pacsin 2 is necessary for cardiac development and function in mouse embryos, which will enhance our knowledge to better understand the genesis of cardiovascular diseases.

Electrophysiological Testing for the Investigation of Bradycardias

In this article we review the role of electrophysiological testing in patients presenting with bradycardia due to sinus node or atrioventricular node disease. In sinus bradycardia the role of electrophysiology studies is not established. In AV conduction disturbances, an electrophysiology study may be necessary both for the establishment of atrioventricular block as the main cause of symptoms, and for identification of the anatomic site of block that may dictate the potential need of permanent pacing.

The reverse mode switch algorithm: how well does it work?

BACKGROUND

The performance of the Reverse Mode Switch (RMS) algorithm, aimed at minimizing right ventricular pacing by operating in the AAI(R) mode with switch to the DDD(R) mode if atrioventricular (AV) conduction loss is detected, is not well known.

OBJECTIVE

To determine the appropriateness of the RMS episodes available from patient follow-up data at our center.

METHODS

Patients with the TELIGEN dual-chamber implantable cardioverter-defibrillator and the RMS algorithm activated were identified. The RMS episodes with available electrograms were analyzed and classified as appropriate (AV conduction loss) or inappropriate (non-AV conduction loss) events. Cumulative percentage of ventricular pacing and amount of premature ventricular complexes (PVCs) were recorded.

RESULTS

Of 21 patients, RMS episodes had occurred in 19 of them, with a mean of 527 episodes per month. Of the 172 RMS episodes available for analysis, 27 (16%) were classified as appropriate and 145 (84%) as inappropriate. Almost all (91%) inappropriate RMS episodes were due to PVC, and there was a positive correlation between the number of total RMS episodes per month and the number of PVCs per month (P < .0005). Considering patients with only inappropriate RMS episodes (n = 11), there was a positive correlation between the percentage of ventricular pacing and the number of RMS episodes per month (P < .05).

CONCLUSIONS

A large majority of the RMS episodes available for analysis inappropriately triggered switch from the AAI(R) mode to the DDD(R) mode owing to PVCs. Patients with the RMS algorithm and elevated PVC burden are probably at risk of a high percentage of unnecessary right ventricular pacing.