Primary Results from the SMART AV DELAY Trial: A Randomized Trial Comparing Empiric, Echocardiographic Guided and Algorithmic AV Delay Programming in Cardiac Resynchronization Therapy (CRT) Kenneth A. Ellenbogen, MD, Michael R. Gold, PhD, MD, Bernd Lemke, MD, Ignacio F. Lozano, MD, Timothy E. Meyer, PhD, Suneet Mittal, MD, Jagmeet P. Singh, MD, Frank G. Spinale, PhD, MD, Kenneth M. Stein, MD, Jennifer E. Van Eyk, PhD, Allan D. Waggoner, MHS for The SMART-AV Trial Investigators.
Presenter Disclosure Information Kenneth A. Ellenbogen, MD Primary Results from the SMART AV DELAY Trial (Boston Scientific) FINANCIAL DISCLOSURE: Research Grants: Boston Scientific, Medtronic, St. Jude Medical, Biosense Webster, Sanofi Consulting / Advisory board: Boston Scientific, Biotronik, Medtronic, St. Jude Medical, Sorin Group, Sanofi, Cardionet, Atricare, EBR Lectures: Boston Scientific, Biotronik, Medtronic, St. Jude Medical, Sorin Group, Sanofi Stock Options: None; Salary Support: None; Speaker Bureau: None UNLABELED/UNAPPROVED USES DISCLOSURE: None All devices used in the SMART-AV trial were Boston Scientific
SMART-AV (Background) • In patients with heart failure and prolonged QRS duration, cardiac resynchronization therapy (CRT) reduces heart failure hospitalizations and prolongs survival compared with optimal medical therapy (OMT). • Achieving the optimal outcome from CRT may be dependent on proper programming of the optimal atrioventricular (AV) delay. • However, large scale randomized trials establishing the overall efficacy of CRT have differed widely in their approach to AV optimization. • CONTAK CD – No optimization • CARE-HF and MIRACLE – Doppler echocardiography of transmitral flow • COMPANION – algorithm based on the intrinsic AV interval and baseline QRS • ASE proposed mitral inflow method for routine AV optimization after CRT
Objectives • To compare three alternative AV optimization techniques and to assess the hypotheses that: 1) systematic AV delay optimization using echocardiography and/or the SD algorithm is superior to a fixed nominal AV delay as demonstrated by improved LV geometry after 6 months and 2) that programming according to SD is non-inferior to using echocardiography-determined AV delay optimization.
Methods SMART-AV Inclusion Primary Endpoint: • NYHA class III or IV - LVESV at 6 months • EF < 0.35 Secondary Endpoints: • QRS >120ms • Expected to be in sinus rhythm at the - 6 min walk, EF, NYHA Class, time of implant LVEDV, QOL (MLWHF) • Willing and capable of undergoing a device implant and participating in all Statistics: testing • Receiving OPT • Continuous outcomes: general linear model - F test SMART-AV Exclusion • Categorical outcomes: risk • Complete heart block or unable to difference of proportions – tolerate pacing at VVI-40-RV for up to 14 Chi-squared test days • Applicable to primary, • Previously received CRT secondary and subgroup analyses
SMART-AV – Study Design Enrollment and Implant CRT-D with SmartDelay Program device to VVI-40-RV Post-Implant Visit (1 to 14 days post-implant) (1:1:1 Randomization, Programmed to DDD(R)60) SmartDelay Echo (Iterative) Fixed (120/0) 3- month Visit 3- month Visit 3- month Visit 6- month Visit 6- month Visit 6- month Visit Stein KM, et al. Pacing Clin Electrophysiol. 2010;33(1):54-63
Baseline Patient Characteristics Characteristics SD Echo Fixed p-value (n=332) (n=323) (n=326) Age (yrs) 66 ± 11 66 ± 11 66 ± 11 ns Gender (% male) 71% 68% 65% ns Resting heart rate (bpm) 71 ± 12 72 ± 13 71 ± 13 ns 25 ± 7 24 ± 7 25 ± 7 Ejection fraction (%) ns QRS duration (ms) 152 ± 21 153 ± 20 153 ± 20 ns History of ventricular fibrillation 2% 1% 2% ns History of paroxysmal atrial fibrillation 11% 11% 14% ns LBBB/RBBB/IVCD (%) 79/11/9 72/16/10 79/11/9 ns Ischemic cardiomyopathy 57% 57% 56% ns NYHA FC II/III/IV heart failure 4/92/4% 2/96/2% 2/95/3% ns Continuous variables are expressed as mean ± SD
SMART-AV – Patient Flow Enrolled Implanted Randomized n=1060 n=1014 n=980 SmartDelay Echo (Iterative) Fixed (120/0) n=332 n=323 n=325 Withdrawn, LTFU Withdrawn, LTFU Withdrawn, LTFU or Missing data or Missing data or Missing data n=49 n=41 n=44 Evaluable Data Evaluable Data Evaluable Data n=283 (85%) n=282 (87%) n=281 (86%)
Primary Endpoint – LVESV
Secondary Structural Endpoints – LVEDV, LVEF
Secondary Functional Endpoints – Six Min Walk, QOL
Secondary Endpoint – NYHA Class
Distribution of AV Delays at 6-months post-implant
Primary Endpoint Subgroup: Etiology, Atrial Pacing %
Primary Endpoint Subgroup: Bundle Branch Block, QRS Width
Primary Endpoint Subgroup: Gender
Summary & Conclusion • The change in LVESV for the SD arm was no different than either the Echo or Fixed arms. • There were no significant differences in the secondary structural or functional endpoints by optimization group. • Patients with a wide QRS duration, LBBB, non-ischemic cardiomyopathy, and female gender responded more favorably to CRT therapy. • In post-hoc analysis, females optimized with SD and Echo responded more favorably than females randomized to the Fixed arm. • The routine use of AV optimization techniques as assessed in this trial is not warranted. However, this data does not exclude possible utility in selected patients who do not respond to CRT.
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