Comparison of left ventricular and biventricular pacing: Rationale and clinical implications

Abstract

Cardiac resynchronization therapy constitutes a cornerstone in advanced heart failure treatment, when there is evidence of dyssynchrony, especially by electrocardiography. However, it is plagued both by persistently high (~30%) rates of nonresponse and by deterioration of right ventricular function, owing to iatrogenic dyssynchrony in the context of persistent apical pacing to ensure delivery of biventricular pacing. Left ventricular pacing has long been considered an alternative to standard biventricular pacing and can be achieved as easily as inserting a single pacing electrode in the coronary sinus. Although monoventricular left ventricular pacing has been proven to yield comparable results with the standard biventricular modality, it is the advent of preferential left ventricular pacing, combining both the powerful resynchronization potential of multipolar coronary sinus and right-sided electrodes acting in concert and the ability to preserve intrinsic, physiological right ventricular activation. In this review, we aim to present the underlying principles and modes for delivering left ventricular pacing, as well as to highlight advantages of preferential over monoventricular configuration. Finally, current clinical evidence, following implementation of automated algorithms, regarding performance of left ventricular as compared with biventricular pacing will be discussed. It is expected that the field of preferential left ventricular pacing will grow significantly over the following years, and its combination with other advanced pacing modalities may promote clinical status and prognosis of patients with advanced dyssynchronous heart failure.

Figure 1

Modes of left ventricular (LV) pacing. (a) Epicardial LV pacing with an electrode (with two or four poles) lodged in the coronary sinus, one to right ventricular apex and one in the right atrium. This configuration may be used to deliver both standard BVP and pLV pacing–see text for differences. (b) Monoventricular epicardial LV pacing (mLV pacing). Note absence of RV electrode. The totality of the heart is activated with a rightward direction (not leading to QRS duration shortening). (c) Endocardial LV pacing–interventricular septum approach–an alternative approach using standard devices, allowing for more versatility in LV site selection. (d) Endocardial LV pacing–the WiSE study approach–although allowing for the greatest versatility regarding site, it does not use CRT devices, rather a dual-chamber pacemaker communicates with an ultrasound generator that in turn activates the electrode in the left ventricle