Cardiac Resynchronization Therapy Is Associated with Reductions in Left Atrial Volume and Inappropriate ICD Therapy in MADIT-CRT
There are no prior studies assessing the relationship between left atrial volume and inappropriate ICD therapy following treatment with cardiac resynchronization therapy.
We hypothesized that patients randomized to CRT-D in the MADIT-CRT trial who had significant left atrial volume (LAV) reductions would have reduced risks of inappropriate ICD therapy.
Cardiac resynchronization remodeling was assessed by measuring LAV change between baseline and 12-month echocardiograms in 751 CRT-D treated patients. Patients were stratified into quartiles based on percent reduction of LAV change: High LAV responders were those in the highest three quartiles of LAV reduction (LAV reduction >21%) and low LAV responders were those in the lowest quartile of LAV reduction (LAV reduction <21%). Clinical factors associated with >21% reduction in LAV were evaluated by linear regression analysis.
In Cox proportional-hazards regression analyses, high LAV responders had a 39% reduction in the risk of inappropriate therapy (hazard ratio 0.61, p=0.04) and LBBB patients exhibited an even greater risk reduction in inappropriate therapy (hazard ratio 0.51, p=0.02) compared to low LAV responders during follow-up extending up to 3 years after the 12-month echocardiogram. High LAV responders also had a significantly lower risk of heart failure or death during follow-up than low LAV responders.
A ≥21% reduction in LAV with cardiac resynchronization therapy is associated with significant reductions in inappropriate ICD therapy and in heart failure or death during a 3-year follow-up.
- SourceAvailable from: Patricia PellikkaJournal of the American Society of Echocardiography: official publication of the American Society of Echocardiography 01/2006; 18(12):1440-63. DOI:10.1016/j.echo.2005.10.005 · 3.99 Impact Factor
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ABSTRACT: Cardiac resynchronization therapy (CRT) plus implantation of an implantable cardioverter defibrillator (ICD) reduced the risk of death or heart failure event in patients with mildly symptomatic heart failure, left ventricular dysfunction, and wide QRS complex compared with an ICD only. We assessed echocardiographic changes in patients enrolled in the MADIT-CRT trial (Multicenter Automatic Defibrillator Implantation Trial: Cardiac Resynchronization Therapy) to evaluate whether the improvement in outcomes with CRT plus an ICD was associated with favorable alterations in cardiac size and function. A total of 1,820 patients were randomly assigned to CRT plus an ICD or to an ICD only in a 3:2 ratio. Echocardiographic studies were obtained at baseline and 12 months later in 1,372 patients. We compared changes in cardiac size and performance between treatment groups and assessed the relationship between these changes over the first year, as well as subsequent outcomes. Compared with the ICD-only group, the CRT-plus-ICD group had greater improvement in left ventricular end-diastolic volume index (-26.2 versus -7.4 mL/m(2)), left ventricular end-systolic volume index (-28.7 versus -9.1 mL/m(2)), left ventricular ejection fraction (11% versus 3%), left atrial volume index (-11.9 versus -4.7 mL/m(2)), and right ventricular fractional area change (8% versus 5%; P<0.001 for all). Improvement in end-diastolic volume at 1 year was predictive of subsequent death or heart failure, with adjustment for baseline covariates and treatment group; each 10% decrease in end-diastolic volume was associated with a 40% reduction in risk (P<0.001). CRT resulted in significant improvement in cardiac size and performance compared with an ICD-only strategy in patients with mildly symptomatic heart failure. Improvement in these measures accounted for the outcomes benefit. Clinical Trial Registration Information- URL: http://www.clinicaltrials.gov. Unique identifier: NCT00180271.Circulation 09/2010; 122(10):985-92. DOI:10.1161/CIRCULATIONAHA.110.955039 · 14.95 Impact Factor
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ABSTRACT: This study aimed to determine whether QRS morphology identifies patients who benefit from cardiac resynchronization therapy with a defibrillator (CRT-D) and whether it influences the risk of primary and secondary end points in patients enrolled in the Multicenter Automatic Defibrillator Implantation Trial-Cardiac Resynchronization Therapy (MADIT-CRT) trial. Baseline 12-lead ECGs were evaluated with regard to QRS morphology. Heart failure event or death was the primary end point of the trial. Death, heart failure event, ventricular tachycardia, and ventricular fibrillation were secondary end points. Among 1817 patients with available sinus rhythm ECGs at baseline, there were 1281 (70%) with left bundle-branch block (LBBB), 228 (13%) with right bundle-branch block, and 308 (17%) with nonspecific intraventricular conduction disturbances. The latter 2 groups were defined as non-LBBB groups. Hazard ratios for the primary end point for comparisons of CRT-D patients versus patients who only received an implantable cardioverter defibrillator (ICD) were significantly (P < 0.001) lower in LBBB patients (0.47; P < 0.001) than in non-LBBB patients (1.24; P = 0.257). The risk of ventricular tachycardia, ventricular fibrillation, or death was decreased significantly in CRT-D patients with LBBB but not in non-LBBB patients. Echocardiographic parameters showed significantly (P < 0.001) greater reduction in left ventricular volumes and increase in ejection fraction with CRT-D in LBBB than in non-LBBB patients. Heart failure patients with New York Heart Association class I or II and ejection fraction ≤ 30% and LBBB derive substantial clinical benefit from CRT-D: a reduction in heart failure progression and a reduction in the risk of ventricular tachyarrhythmias. No clinical benefit was observed in patients with a non-LBBB QRS pattern (right bundle-branch block or intraventricular conduction disturbances). URL: http://www.clinicaltrials.gov. Unique identifier: NCT00180271.Circulation 02/2011; 123(10):1061-72. DOI:10.1161/CIRCULATIONAHA.110.960898 · 14.95 Impact Factor