Multipoint left ventricular pacing effects on hemodynamic parameters and functional status: HUMVEE single-arm clinical trial (NCT03189368)

Multipoint Left Ventricular Pacing as Alternative Approach in Cases of Biventricular Pacing Failure

Cardiac resynchronization therapy (CRT) is a cornerstone in the treatment of dyssynchronous heart failure with reduced ejection fraction. However, the phenomenon of non-response has plagued CRT since its initial application. Notwithstanding issues such as failure to capture the left ventricle, lower-than-required pacing delivery percent, and failure to optimize atrioventricular and interventricular delays, there are patients who fail to exhibit an adequate response to CRT in its classical biventricular pacing (BiVP) form. Several modalities have been proposed as a means to remedy this issue, including pacing the conduction system itself-His or left bundle branch pacing, allowing for intrinsic conduction in some myocardial segments, pacing the left ventricle from multiple points in the coronary sinus (multipoint pacing), or even combining the above (e.g., His/left bundle pacing and BiVP leading to His/left bundle-optimized CRT). In the present review, we present recent evidence for the advantages and disadvantages of each modality and attempt to formulate a pathophysiology and simulation-based strategy to determine the best way forward for delivering CRT in non-responders to BiVP.

Multisite Left Ventricular Pacing in Cardiac Resynchronization Therapy

Cardiac resynchronization therapy (CRT) is an established treatment of patients with heart failure with reduced ejection fraction and prolonged ventricular depolarization on surface electrocardiogram. Although patients' characteristics, such as their type of cardiomyopathy and the morphology and width of their baseline QRS complex, have been associated with CRT response, these features are not modifiable. Left ventricular multisite pacing has been proposed and tested as a tool to improve response to CRT and positively impact patient outcomes. This article reviews the published literature on left ventricular multisite pacing, with focus on the results of recently presented or published clinical trials.

Comparative Trial of the Effects of Left Ventricular and Biventricular Pacing on Indices of Cardiac Function and Clinical Course of Patients With Heart Failure: Rationale and Design of the READAPT Randomized Trial

Nonresponse to cardiac resynchronization therapy (CRT) has been related with right ventricular dysfunction. Ventriculoarterial coupling (VAC) assesses energy efficiency of the failing heart and stroke work maximization for a given contractility, for both systemic and pulmonary circulations. Preferential left ventricular pacing (pLVP) can overcome iatrogenic right ventricular dysfunction by achieving left ventricle resynchronization and by allowing for intrinsic activation of the right side, with ramifications extending beyond cardiac output and atrial fibrillation occurrence. In the present article, we detail the design of a single-center randomized clinical trial to evaluate the effects of a pLVP algorithm. More specifically, following randomization of 220 CRT-eligible patients to standard biventricular pacing and pLVP, their clinical course will be followed for 12 months, through echocardiography to study indices of systolic and diastolic function of ventricles, left and right side VAC to evaluate efficiency, and cardiopulmonary exercise test to objectively document improvements in functional status, as well as a self-reported quality of life questionnaire. Device programming will be based on echocardiography-evaluated maximization of stroke volume and subsequent interventricular and atrioventricular delay adjustments delegated to the device. Findings of this trial may provide evidence for alternative programming of the devices, linking pLVP to improved clinical outcomes.