Effect of elevated heart rate preceding the onset of XXXX on antitachycardia pacing effectiveness in @entity1 with @entity737 .

@entity1 @entity1479 @entity296 @entity1165 @entity63 @entity737 @entity591 @entity2224 @entity7129 @entity855
The incorporation of antitachycardia pacing ( @entity855 ) into @entity737 ( @entity737 ) has provided a better tolerated alternative to shocks. @entity855 has been shown to be effective in terminating approximately 80% to 90% of spontaneous @entity1165 ( @entity1165 ) episodes. Although @entity855 is routinely used, little is known about predictors of @entity855 failure. Based on the evaluation of stored electrograms, we aimed to prospectively follow @entity1 with @entity737 , and to analyze parameters affecting @entity855 effectiveness. One hundred eighteen consecutive @entity1 received @entity737 for standard indications. Before discharge, empirical, standardized @entity855 therapy was programmed in all @entity1 within @entity1165 zones. A total of 1,218 spontaneous @entity591 episodes occurred in 51 @entity1 during a mean follow-up of 24.5 +/- 12 months. Among these, 888 VTs were diagnosed. One hundred four fast VTs were detected in the @entity2224 zone and treated with primary shock delivery. @entity855 was attempted 881 times in the remaining 784 @entity1165 episodes. @entity855 terminated 640 VTs successfully, @entity855 failed in 55 VTs finally reverted by shocks, and 89 VTs converted to a slower @entity1165 outside the @entity1165 zone. Fifty-one of these slower VTs reverted spontaneously, and 38 were redetected and treated. Finally, in primary intention-to-treat basis, @entity855 was successful in 691 VTs (88%) and unsuccessful in 93 VTs (12%). There was no influence of @entity1165 cycle length on @entity855 success rate. Furthermore, @entity855 efficacy was similar between @entity1 with left ventricular ejection fraction < or =35% or >35%, between daytime and nighttime, as well as between @entity1 with @entity63 or nonischemic @entity296 . A faster heart rate immediately preceding the onset of @entity1165 (103 +/- 19 vs 78 +/- 14 beats/min, respectively, hazard ratio 4.08, 95% confidence interval 2.11 to 7.89, p <0.001), and absence of beta-blocker therapy (82% vs 93%, respectively, hazard ratio 2.71, 95% confidence interval 1.72 to 4.29, p = 0.02) were found, by Cox proportional-hazard analysis, to be the sole independent predictors of @entity855 ineffectiveness in @entity1479 recipients. Thus, the present study identified both preceding @entity7129 (reflecting an increased sympathetic tone) and lack of beta-blocker use as independent risk factors for reduced success of @entity855 therapy in terminating @entity1165 . Therefore, modification of sympathetic tone may be beneficial for @entity1 with @entity737 .
