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...

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This feasibility study shows that DHBP can be accomplished with a new system consisting of a steerable catheter and an active fixation lead in 92% of the patients in whom it was attempted.

This study suggests that moderate-to-severe ASA might be associated with LA dysfunction in patients with PFO. The resultant similarities to the pathophysiology of AF might represent an additional contributing mechanism for arterial embolism in such patients.

Compared with BiV pacing at any LV site, MPP yielded a small but consistent increase in hemodynamic response. A correlation between the increase in hemodynamics and Q-LV on MPP was observed for all measurements, including those taken at the best and worst sites. The MPP-induced improvement in contractility was associated with significantly greater narrowing of the QRS complex than conventional BiV pacing.

HA pacing compared with RVA or RVS pacing seems to be associated with a lower risk of persistent/permanent AF occurrence. The risk of persistent/permanent AF was similar in the RVA vs. RVS groups.

Combining MPP with optimal positioning of the LV lead on the basis of electrical delay and hemodynamics enhances reverse remodeling and improves clinical outcomes beyond the effect due to conventional CRT.

The degree of LV dyssynchrony induced by RVA is variable. Patients with higher baseline LV dyssynchrony, more dilated LV, and more depressed LVEF showed a higher degree of LV dyssynchrony during pacing. These findings may assume importance in predicting the risk of heart failure in pacemaker patients.