Full-Body MRI in Patients With an Implantable Cardioverter-Defibrillator Primary Results of a Randomized Study

AbstractBackgroundMagnetic resonance imaging (MRI) of patients with conventional implantable cardioverter-defibrillators (ICD) is contraindicated.ObjectivesThis multicenter, randomized trial evaluated safety and efficacy of a novel ICD system specially designed for full-body MRI without restrictions on heart rate or pacing dependency. The primary safety objective was >90% freedom from MRI-related events composite endpoint within 30 days post-MRI. The primary efficacy endpoints were ventricular pacing capture threshold and ventricular sensing amplitude.MethodsSubjects received either a single- or dual-chamber ICD. In a 2:1 randomization, subjects either underwent MRI at 1.5-T of the chest, cervical, and head regions to maximize radiofrequency exposure up to 2 W/kg specific absorption rate and gradient field exposure to 200 T/m/s per axis (MRI group, n = 175), or they underwent a 1-h waiting period without MRI (control group, n = 88). A subset of MRI patients underwent ventricular fibrillation induction testing post-MRI to characterize defibrillation function.ResultsIn 42 centers, 275 patients were enrolled (76% male, age 60.4 ± 13.8 years). The safety endpoint was met with 100% freedom from the composite endpoint (p < 0.0001). Both efficacy endpoints were met with minimal differences in the proportion of MRI and control patients who demonstrated a ≤0.5 V increase in ventricular pacing capture threshold (100% MRI vs. 98.8% control, noninferiority p < 0.0001) or a ≤50% decrease in R-wave amplitude (99.3% MRI vs. 98.8% control, noninferiority p = 0.0001). A total of 34 ventricular tachyarrhythmia/ventricular fibrillation episodes (20 induced; 14 spontaneous) occurred in 24 subjects post-MRI, with no observed effect on sensing, detection, or treatment.ConclusionsThis is the first randomized clinical study of an ICD system designed for full-body MRI at 1.5-T. These data support that the system is safe and the MRI scan does not adversely affect electrical performance or efficacy. (Confirmatory Clinical Trial of the Evera MRI System for Conditionally-Safe MRI Access; NCT02117414

Continuous optimization of cardiac resynchronization therapy reduces atrial fibrillation in heart failure patients: Results of the Adaptive Cardiac Resynchronization Therapy Trial

BackgroundData from randomized trials have suggested a modest or no effect of conventional cardiac resynchronization therapy (convCRT) on the incidence of atrial fibrillation (AF). AdaptivCRT (aCRT, Medtronic, Mounds View, MN) is a recently described algorithm for synchronized left ventricular (LV) pacing and continuous optimization of cardiac resynchronization therapy (CRT).ObjectiveWe compared the long-term effects of aCRT with convCRT pacing on the incidence of AF.MethodsThe Adaptive CRT trial randomized CRT-defibrillator (CRT-D)–indicated patients (2:1) to receive either aCRT or convCRT pacing. The aCRT algorithm evaluates intrinsic conduction every minute, providing LV-only pacing during normal atrioventricular (AV) conduction and AV and ventriculoventricular timing adjustments during prolonged AV conduction. The primary outcome of this subanalysis was an episode of AF >48 consecutive hours as detected by device diagnostics.ResultsOver a follow-up period with a mean and standard deviation of 20.2 ± 5.9 months, 8.7% of patients with aCRT and 16.2% with convCRT experienced the primary outcome (hazard ratio [HR] = 0.54; 95% confidence interval [CI] = 0.31–0.93; P = .03). In patients with prolonged baseline AV, the incidence of the primary outcome was 12.8% in patients randomized to aCRT compared with 27.4% in convCRT patients (HR = 0.45; 95% CI = 0.24–0.85; P = .01). Also, patients with AF episodes adjudicated as clinical adverse events were less common with aCRT (4.3%) than with convCRT (12.7%) (HR = 0.39; 95% CI = 0.19–0.79; P = .01).ConclusionPatients receiving aCRT had a reduced risk of AF compared with those receiving convCRT. Most of the reduction in AF occurred in subgroups with prolonged AV conduction at baseline and with significant left atrial reverse remodeling

The Association of Left Ventricular Remodeling with CRT Outcomes

International audienceBACKGROUND: Cardiac resynchronization therapy (CRT) response stratified by left ventricular (LV) remodeling revealed differing mortality profiles for distinct patient cohorts. Measuring functional endpoints, as well as mortality, may better assess CRT efficacy and inform patient management. However, the association between LV remodeling and functional outcomes after CRT is not well understood. OBJECTIVE: To evaluate long-term CRT outcomes by extent of LV remodeling. METHODS: REsynchronization reVErses Remodeling in Systolic Left vEntricular Dysfunction (NCT00271154) was a prospective, double-blind, randomized CRT trial. Patients were classified based on LV end-systolic volume (LVESV) change from baseline to 6-months post-CRT: Worsened (increase); Stabilized (0 to ≤15% reduction); Responder (&gt;15 to &lt; 30% reduction); and Super-responder (≥30% reduction). Subjects were evaluated annually for 5 years. RESULTS: The analyses included 353 patients randomized to CRT-ON arm. All-cause mortality was higher in the worsened group compared with the 3 other response groups (29.8% vs 8.0%, p&lt;0.0001), with no difference in survival among those groups (p=0.87). A significant interaction between LVESV group and time was observed for health status and quality of life (both p=0.02). The interaction was not significant for 6-minute hall walk (p=0.79); however, super-responders had increased walk distance compared to the 3 other response groups (p=0.03). CONCLUSION: Preventing further increase in LVESV with CRT was associated with reduced mortality, whereas functional measure improvement was associated with LV remodeling magnitude. These results support consideration of functional and mortality endpoints to assess CRT efficacy and provide further evidence the dichotomous ’responder and non-responder’ classification should be modified

The effect of reverse remodeling on long-term survival in mildly symptomatic patients with heart failure receiving cardiac resynchronization therapy: Results of the REVERSE study

International audienceBackground Cardiac resynchronization therapy (CRT) reduces mortality, improves functional status, and induces reverse left ventricular remodeling in selected populations with heart failure (HF). The magnitude of reverse remodeling predicts survival with many HF medical therapies. However, there are few studies assessing the effect of remodeling on long-term survival with CRT. Objective The purpose of this study was to assess the effect of CRT-induced reverse remodeling on long-term survival in patients with mildly symptomatic heart failure. Methods The REsynchronization reVErses Remodeling in Systolic Left vEntricular Dysfunction trial was a multicenter, double-blind, randomized trial of CRT in patients with mild HF. Long-term follow-up of 5 years was preplanned. The present analysis was restricted to the 353 patients who were randomized to the CRT ON group with paired echocardiographic studies at baseline and 6 months postimplantation. The left ventricular end-systolic volume index (LVESVi) was measured in the core laboratory and was an independently powered end point of the REsynchronization reVErses Remodeling in Systolic Left vEntricular Dysfunction trial. Results A 68% reduction in mortality was observed in patients with ≥15% decrease in LVESVi compared to the rest of the patients (P = .0004). Multivariable analysis showed that the change in LVESVi was a strong independent predictor (P = .0002), with a 14% reduction in mortality for every 10% decrease in LVESVi. Other remodeling parameters such as left ventricular end-diastolic volume index and ejection fraction had a similar association with mortality. Conclusion The change in left ventricular end-systolic volume after 6 months of CRT is a strong independent predictor of long-term survival in mild H

Effects of Cardiac Resynchronization Therapy on Cardiac Remodeling and Contractile Function: Results From Resynchronization Reverses Remodeling in Systolic Left Ventricular Dysfunction (REVERSE)

International audienceBackground Cardiac resynchronization therapy results in improved ejection fraction in patients with heart failure. We sought to determine whether these effects were mediated by changes in contractility, afterload, or volumes. Methods and Results In 610 patients with New York Heart Association class I/II heart failure from the Resynchronization Reverses Remodeling in Systolic Left Ventricular Dysfunction (REVERSE) study, we performed detailed quantitative echocardiography assessment prior to and following cardiac resynchronization therapy. We derived measures of contractility (the slope [end‐systolic elastance] and the volume intercept of the end‐systolic pressure–volume relationship, stroke work, and preload recruitable stroke work), measures of arterial load and ventricular–arterial coupling, and measures of chamber size (volume intercept, end‐systolic and end‐diastolic volumes). At 6 and 12 months, cardiac resynchronization therapy was associated with a reduction in the volume intercept and end‐systolic and end‐diastolic volumes (P\textless0.01). There were no consistent effects on end‐systolic elastance, stroke work, preload recruitable stroke work, or ventricular–arterial coupling. In the active cardiac resynchronization therapy population, baseline measures of arterial load were associated with the clinical composite score (odds ratio 1.30, 95% CI 1.04 to 1.63, P=0.02). The volume intercept was associated with mortality (hazard ratio 1.90, 95% CI 1.01 to 3.59, P=0.047) and more modestly with the combined end point of mortality or heart failure hospitalization (hazard ratio 1.48, 95% CI 0.8 to 2.25, P=0.06). In contrast, end‐systolic elastance, stroke work, preload recruitable stroke work, and ventricular–arterial coupling were not associated with any outcomes. Conclusion In patients with NYHA Class I/II heart failure, cardiac resynchronization therapy exerts favorable changes in left ventricular end‐systolic and end‐diastolic volumes and the volume intercept. The volume intercept may be useful to gain insight into prognosis in heart failure. Clinical Trial Registration URL: https://www.clinicaltrials.gov/. Unique identifier: NCT0027115