Determination of the Longest Intrapatient Left Ventricular Electrical Delay May Predict Acute Hemodynamic Improvement in Patients After Cardiac Resynchronization Therapy

Abstract

Background-One of the reasons for patient nonresponse to cardiac resynchronization therapy is a suboptimal left ventricular (LV) pacing site. LV electric delay (Q-LV interval) has been indicated as a prognostic parameter of cardiac resynchronization therapy response. This study evaluates the LV delay for the optimization of the LV pacing site. Methods and Results-Thirty-two consecutive patients (23 men; mean age, 71±11 years; LV ejection fraction, 30±6%; 18 with ischemic cardiomyopathy; QRS, 181±25 ms; all mean±SD) underwent cardiac resynchronization therapy device implantation. All available tributary veins of the coronary sinus were tested, and the Q-LV interval was measured at each pacing site. The hemodynamic effects of pacing at different sites were evaluated by invasive measurement of LV dP/dt max at baseline and during pacing. Overall, 2.9±0.8 different veins and 6.4±2.3 pacing sites were tested. In 31 of 32 (96.8%) patients, the highest LV dP/dt max coincided with the maximum Q-LV interval. Q-LV interval correlated with the increase in LV dP/dt max in all patients at each site (AR1 ρ=0.98; P<0.001). A Q-LV value >95 ms corresponded to a >10% in LV dP/dt max . An inverse correlation between paced QRS duration and improvement in LV dP/dt max was seen in 24 patients (75%). Conclusions-Pacing the LV at the latest activated site is highly predictive of the maximum increase in contractility, expressed as LV dP/dt max . A positive correlation between Q-LV interval and hemodynamic improvement was found in all patients at every pacing site, a value of 95 ms corresponding to an increase in LV dP/dt max of ≥10%. (Circ Arrhythm Electrophysiol. 2014;7:377-383.)Key Words: cardiac resynchronization therapy ◼ cardiomyopathies ◼ heart failure ◼ hemodynamics Received July 11, 2013; accepted March 14, 2014. interval-the interval from the onset of the intrinsic QRS on the surface ECG to the first large peak of the LV electrogram) and hemodynamics was derived from single measurements in each patient and, therefore, cannot be extrapolated to the use of Q-LV interval within an individual patient. The aims of our study were to investigate acute hemodynamic improvement during LV pacing from all available sites within a patient, as well as to test the hypothesis that the region with the longest electric delay provides the best hemodynamic response. MethodsWe analyzed the relationship between LV dP/dt max increase and LV electric delay in a CRT population. The study was approved by the local ethics board, and all patients provided written informed consent.In accordance with our standard implantation procedure, the right ventricular and atrial leads were positioned in conventional sites in all patients. Specifically, the right ventricular leads were implanted in the midseptum. The coronary sinus was cannulated via a telescopic approach, as previously described 18 ; coronary sinus angiography was performed, and all suitable collateral veins were subcannulated and visualized selectively. For the purpose of the present article, we def...

Optimal site selection and image fusion guidance technology to facilitate cardiac resynchronization therapy

“…Theoretically, the site of latest activation should exhibit the most dyssynchrony and as such would represent an ideal pacing site. While some work appears to confirm the site of LEA is synonymous with the optimal pacing site [21], more recent analysis has shown optimal site exhibits late but not supremely delayed activation [100]. Sites demonstrating excessively delayed activity may in fact merely represent distal activation occurring within islands of non-viable tissue.…”

“…Both of these studies retrospectively analyzed the degree of electrical latency at the site of LV lead deployment; however, Zanon et al evaluated whether Q-LV might be used to identify the optimal site in an individual patient by systematically screening all of the suitable coronary sinus (CS) veins [21]. A strong correlation was observed between Q-LV prolongation and improvements in acute hemodynamic response.…”

“…There is also no consensus as to whether delivering BiV pacing at a site which achieves a narrowing of the paced QRS is associated with improvements in hemodynamics. While some work has shown a correlation between narrowing of the QRS and improvements in AHR [100], this finding has not been consistently replicated [21]. …”

Developments in Cardiac Resynchronisation Therapy

“…36 Thus targeting the site of latest electrical activation, as defined by a QLV interval greater than the median of 95 ms, can improve patient response to CRT. Subgroup analyses from these trials show that this is a robust predictor of response, even among subjects with non-LBBB, ischaemic aetiology or QRS duration <150 ms.…”

Personalised Biophysical Model to Optimise Left Ventricle Pacing Location for Cardiac Resynchronisation Therapy Over Time

“…To improve the response rate of patients, the optimal location from which to pace the LV free wall has therefore received some interest. In earlier studies, it was found that the optimal location from which to pace the LV is in the non-ischemic, non-apical, postero-lateral/lateral regions of the LV epicardium, or the latest point of mechanical or electrical activation [4][5][6].The heart remodels in response to sustained pacing with regards to the anatomy, mechanics and electrophysiology properties [7,8]. New pacing catheter technologies such as multipole pacing (MPP) and multi-vein pacing (MVP) allow for the LV lead position to be altered post implant without further surgery.…”