Primary Results From the SmartDelay Determined AV Optimization: A Comparison to Other AV Delay Methods Used in Cardiac Resynchronization Therapy (SMART-AV) Trial

Abstract

Background-One variable that may influence cardiac resynchronization therapy response is the programmed atrioventricular (AV) delay. The SmartDelay Determined AV Optimization: A Comparison to Other AV Delay Methods Used in Cardiac Resynchronization Therapy (SMART-AV) Trial prospectively randomized patients to a fixed empirical AV delay (120 milliseconds), echocardiographically optimized AV delay, or AV delay optimized with SmartDelay, an electrogram-based algorithm. Methods and Results-A total of 1014 patients (68% men; mean age, 66Ϯ11 years; mean left ventricular ejection fraction, 25Ϯ7%) who met enrollment criteria received a cardiac resynchronization therapy defibrillator, and 980 patients were randomized in a 1:1:1 ratio. All patients were programmed (DDD-60 or DDDR-60) and evaluated after implantation and 3 and 6 months later. The primary end point was left ventricular end-systolic volume. Secondary end points included New York Heart Association class, quality-of-life score, 6-minute walk distance, left ventricular end-diastolic volume, and left ventricular ejection fraction. The medians (quartiles 1 and 3) for change in left ventricular end-systolic volume at 6 months for the SmartDelay, echocardiography, and fixed arms were Ϫ21 mL (Ϫ45 and 6 mL), Ϫ19 mL (Ϫ45 and 6 mL), and Ϫ15 mL (Ϫ41 and 6 mL), respectively. No difference in improvement in left ventricular end-systolic volume at 6 months was observed between the SmartDelay and echocardiography arms (Pϭ0.52) or the SmartDelay and fixed arms (Pϭ0.66). Secondary end points, including structural (left ventricular end-diastolic volume and left ventricular ejection fraction) and functional (6-minute walk, quality of life, and New York Heart Association classification) measures, were not significantly different between arms. Conclusions-Neither SmartDelay nor echocardiography was superior to a fixed AV delay of 120 milliseconds. The routine use of AV optimization techniques assessed in this trial is not warranted. However, these data do not exclude possible utility in selected patients who do not respond to cardiac resynchronization therapy. Clinical Perspective on p 2668Achieving the optimal outcome from CRT may be dependent on proper programming of the optimal atrioventricular (AV) delay. 13,14 Suboptimal AV delay programming can result in as much as a 10% to 15% decline in cardiac output. 15,16 However, the large-scale randomized clinical trials establishing the overall efficacy of CRT have differed widely in their approach to AV optimization. In the CONTAK CD trial, there was no AV optimization. 6 In contrast, the Cardiac Resynchronization-Heart Failure (CARE-HF) and Multicenter InSync Randomized Clinical Evaluation (MIRACLE) investigators used Doppler echocardiography of transmitral flow to select the optimal AV delay, 2,3,13,14,17 an approach endorsed by the American Society of Echocardiography. 18 In further contrast, the Comparison of Medical Therapy, Pacing, and Defibrillation in Heart Failure (COMPANION) investigators used an algorithm based on the i...

2015 HRS/EHRA/APHRS/SOLAECE expert consensus statement on optimal implantable cardioverter-defibrillator programming and testing

“…Echocardiographic optimization of atrioventricular delays in CRT patients can alleviate HF symptoms and increase exercise capacity compared with nominal programming, particularly when approaching nonresponding populations [68]. However, echocardiographic optimization in the PROSPECT study did not support this approach in a randomized trial, and the Frequent Optimization Study Using the QuickOpt Method (FREEDOM) trials failed to provide evidence supporting the benefit of CRT optimization and did not demonstrate superiority of the respective algorithms over nominal or empiric programming [69][70][71]. There are limited data supporting the use of LV-only stimulation in a small subset of patients who fail to respond to biventricular stimulation [72].…”

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

“…In a sub-study of the SMART AV trial [101], patients were again dichotomized, although this time according to the median Q-LV value (95 ms). Gold et al showed that implanting the LV lead at a site with a favorable Q-LV was independently associated with symptomatic improvement and greater reverse remodeling at 6 months [19].…”

2013 ESC Guidelines on Cardiac Pacing and Cardiac Resynchronization Therapy

“…Un pequeño estudio aleatorizado y algunas series de observación han mostrado mejorías significativas de los síntomas de IC y hospitalizaciones por IC después de optimizar los retrasos AV o VV 74,75,w134-w143 , sobre todo en pacientes con IC isquémi-ca w144 . Estos hallazgos no se confirmaron con los resultados de estudios multicéntricos más amplios [76][77][78][79][80][81][82][83] , lo que indica que optimizar sistemáticamente el retraso VV y AV tiene poco efecto en los resultados clínicos o ecocardiográficos obtenidos por quienes reciben TRC, en comparación con un retraso AV fijo de 100-120 ms y estimulación cardiaca biventricular (VD y VI) simultánea (tabla web 12). La selección del paciente, los tiempos del procedimiento y la metodología empleada (algoritmos de dispositivo, ECG o ecocardiografía) no fueron homogéneos entre todos los estudios, lo que impide obtener conclusiones firmes.…”

“…web 9). Se han propuesto varios métodos para optimizar el retraso AV y VV (tabla 13) [74][75][76][77][78][79][80][81][82][83] . Estos métodos pueden clasificarse en dos grupos principales: métodos basados en la ecocardiografía y no basados en la ecocardiografía.…”