Patient Selection for Biventricular Pacing

Abstract

Biventricular Pacing. Introduction: Biventricular pacing improves functional status in the majority of patients with drug-refractory heart failure, dilated cardiomyopathy, and interventricular conduction delay. The aim of this study was to analyze the baseline clinical and functional data of a cohort of patients implanted with a biventricular stimulation system in a single-center experience, to verify if the pathophysiologic characteristics of patients affect outcome, and to determine if preliminary identification of the right candidates for the new therapy is possible with noninvasive parameters.Methods and Results: Since March 1999, 52 patients with advanced heart failure (idiopathic cardiomyopathy 50%, ischemic cardiomyopathy 35 %, other etiology 15%) and left bundle branch block underwent cardiac resynchronization and were followed prospectively. Paired analysis over mean (± SD) follow-up of 348 ± 154 days showed an overall significant decrease of QRS width (baseline 194 ± 33.2 msec vs follow-up 159.6 ± 20.1 msec), New York Heart Association (NYHA) functional class (baseline 3.2 ± 0.5 vs follow-up 2.3 ± 0.5), quality-of-Iife score (baseline 54 ± 25 vs follow-up 25 ± 16), and increase of maximal VOz (baseline 12.6 ± 2.5 mLlkg/min vs follow-up 15.0 ± 3.3 mLlkg/min). There were 80% responders (documented, persistent decrease zel NYHA class) and 20% nonresponders (same NYHA class or decline of status; need for heart transplant; death due to progressive pump failure). No significant differences in baseline clinical and functional variables between the two subgroups were observed. In responders, there was a highly significant global improvement of all variables; in nonresponders, no parameters changed between baseline and follow-up.Conclusion: These data confirm the role of biventricular pacing in improving the functional status of the great majority of a selected patient population having advanced heart failure and left bundle branch block with wide QRS complex. Basal demographic, clinical, and functional characteristics are not helpful in preliminary selection of responders. Simple evaluation of NYHA class confirms favorable outcome (improvement of functional and hemodynamic status).

Additional benefits of nonconventional modalities of cardiac resynchronization therapy using His bundle pacing

“…These findings are concordant with the presumed mechanism of CRT benefit, since reduction in the total ventricular activation time, as measured by the QRS width, probably reflects a reduction in electrical dyssynchrony. Nevertheless, the magnitude of this shortening is generally suboptimal, ranging from 20 to 30 ms in the literature and in the present study, and, therefore, QRS almost invariably remains wide 3–7 . We found that HBP + CS and TRIPLE configurations, but not HBP alone, yielded additional shortening of 16 ms and 23 ms, respectively, which suggests a potentially better clinical outcome (Figure 2A).…”

“…In the PROSPECT-ECG study, 16 shortening is generally suboptimal, ranging from 20 to 30 ms in the literature and in the present study, and, therefore, QRS almost invariably remains wide. [3][4][5][6][7] We found that HBP + CS and TRIPLE configurations, but not HBP alone, yielded additional shortening of The frontal plane QRS axis has only seldom been assessed in CRT studies, mostly as a preimplantation predictor of response, and with modest and contrasting results 16,[18][19][20] ; the paced QRS axis has also been used to assess the relative contribution of RV and LV pacing at different VV intervals or pacing sites. 21,22 In general, the paced QRS axis has not reached the level of confidence required for its use in clinical practice.…”

“…Persistence of wide QRS and an altered QRS axis on conventional CRT suggest incomplete electrical resynchronization. Although conventional biventricular pacing (CONV) is usually able to shorten QRS width, the magnitude of this shortening generally ranges from 20 to 30 ms and QRS almost invariably remains wide 3–8 . During conventional CRT, the QRS axis is greatly altered.…”

“…conventional biventricular pacing (CONV) is usually able to shorten QRS width, the magnitude of this shortening generally ranges from 20 to 30 ms and QRS almost invariably remains wide. [3][4][5][6][7][8] During conventional CRT, the QRS axis is greatly altered. The QRS complex is often positive in lead V1 and the axis on the frontal plane usually points to the right superior quadrant, suggesting a markedly altered sequence of electrical activation.…”

Limited Response to Cardiac Resynchronization Therapy in Patients with Concomitant Right Ventricular Dysfunction

“…Of those treated by CRT, 20–30% experience no clinical benefit 6–12 . Previous studies have attempted to predict both responders and nonresponders to CRT 6,13–16 . A lack of response has been previously reported when LV dyssynchrony is absent, 7,17,18 the pulmonary artery systolic pressure is elevated, 19 LV lead location is suboptimal, 20–22 and the etiology of the cardiomyopathy is ischemic 3 .…”