Cardiac resynchronization therapy pacemaker: critical appraisal of the adaptive CRT-P device

Abstract

Cardiac resynchronization therapy (CRT) is an effective and well-established therapy for patients suffering with heart failure, left ventricular (LV) systolic dysfunction (ejection fraction ≤35%), and electrical dyssynchrony, demonstrated by a surface QRS duration of ≥120 ms. Patients undergoing treatment with CRT have shown significant improvement in functional class, quality of life, LV ejection fraction, exercise capacity, hemodynamics, and reverse remodeling of LV, and ultimately, morbidity and mortality. However, 30%–40% of patients who receive a CRT device may not show improvement, and they are termed as non responders. The nonresponders have a poor prognosis; several methods have been developed to try to enhance response to CRT. Echocardiography-guided optimization of CRT has not resulted in significant clinical benefit, since it is done at rest with the patient in supine position. An ideal optimization strategy would provide continuous monitoring and adjustment of device pacing to provide maximal cardiac resynchronization, under a multitude of physiologic states. Intrinsic activation of the right ventricle (RV) with paced activation of the RV, even in the setting of biventricular (BiV) pacing, may result in an adverse effect on cardiac performance. With this physiology, the use of LV-only pacing may be preferred and may enhance CRT. Adaptive CRT is a novel device-based algorithm that was designed to achieve patient-specific adjustment in CRT so as to provide appropriate BiV pacing or LV-only pacing. This article will review the goals of CRT optimization, and implementation and outcomes associated with adaptive CRT.

Rationale and design of the AdaptResponse trial: a prospective randomized study of cardiac resynchronization therapy with preferential adaptive left ventricular‐only pacing

“…The application of the AdaptivCRT mode provides a novel pacing algorithm specifically designed for preferential LV‐only RV‐synchronized pacing with conduction time‐adaptive AV delay, to maximize fusion of RV and LV activation and achieve optimized LV and BiV pacing 17. The AdaptivCRT pre‐market approval study has demonstrated that AdaptivCRT‐optimized CRT is at least as effective as echo‐optimized BiV pacing determined by the CCS24 (73.6% improved in the AdaptivCRT arm vs. 72.5% in the echo‐optimized arm, P < 0.001 for non‐inferiority with a non‐inferiority margin of 12%18).…”

“…The AdaptivCRT ® (Medtronic plc) algorithm16, 17 has been developed to provide RV‐synchronized LV‐only fusion pacing (i.e. to produce fusion of left‐ and right‐sided ventricular activation) when intrinsic AV conduction is normal or, alternatively, BiV pacing, when required.…”

Left Univentricular Pacing by Rate-Adaptive Atrioventricular Delay in Treatment of Chronic Heart Failure

“…In recent years, 3-chamber pacemakers based on the algorithm of left univentricular pacing adaptive CRT have been used clinically. Studies showed that the application of this algorithm could improve the response rate by 12% compared to the traditional CRT [ 27 , 28 ]. Thus, the comparison of the accuracy and clinical efficacy of these 2 left univentricular pacing algorithms in tracking the physiological AVD is essential in subsequent studies.…”

Outcomes Before and After the Recall of a Heart Failure Pacemaker

“…In November 2015, Medtronic notified physicians that its InSync III model 8042 cardiac resynchronization therapy pacemaker (CRT-P) could fail unexpectedly because of high internal battery impedance (HIBI) caused by the buildup of a resistive film on the cathode current collector . High internal battery impedance decreases current flow from the battery and may result in abrupt cessation of pacing.…”

“…High internal battery impedance decreases current flow from the battery and may result in abrupt cessation of pacing. The manufacturer’s modeling estimated that the risk of failure for the approximately 9300 devices that remained implanted in the United States at that time was 0.16% to 0.6% …”