Effects of CRT Optimization as Assessed by Cardiac MR

Cardiac resynchronization therapy (CRT), or atrial-synchronized biventricular (BiV) pacing, is an FDA-approved device therapy option for heart failure (HF) patients with reduced left ventricular ejection fraction and electrical dyssynchrony. A traditional CRT device has pacing leads implanted within the right atrium (RA), the right ventricle (RV), and within a coronary vein overlying the lateral or posterior left ventricle (LV). Within the past decade, various multi-center randomized controlled trials have reported improved quality of life, aerobic exercise capacity, LV systolic function and structure, as well as decreased hospitalization rates and mortality among patients with HF. Despite improvements in CRT technology with multipoint pacing, quadripolar leads, and adaptive pacing algorithms, approximately 30% of patients do not clinically benefit and are considered non-responders. This study looks to optimize CRT device programming in patients considered non-responders to CRTusing information obtained from standard ECG machines, and to assess acute and chronic effects of CRT optimization using cardiac magnetic resonance imaging (CMR).

This is a prospective, randomized study designed to evaluate if CRT device optimization, guided by electrocardiography, improves cardiac function and clinical outcomes among patients considered non-responders to CRT. All patients will have electrocardiographic assessment of electrical dyssynchrony at a range of device settings using standard ECG machines. All patients will then have a baseline CMR study at baseline CRT programming, underlying rhythm, and optimal settings derived from the electrocardiographic assessment to assess acute effects of CRT optimization on mechanical synchrony, LV regional wall motion, and LV structure/ function. To assess chronic effects of CRT optimization, patients will be randomized in a 1:1 ratio after baseline CMR to either the active comparator arm (baseline CRT programming), or the experimental arm (CRT device programmed to optimal settings derived from the electrocardiographic assessment). Patients will be blinded to randomization. After 6 month, all patients will return for follow up CMR study to assess chronic effects. After follow up CMR imaging, the active comparator group will crossover to the experimental group. After 12 months, all patients will return for follow up echocardiogram to further evaluate the chronic effects of CRT optimization.

Eligibility Criteria:
Inclusion Criteria:

1. Currently on standard medical therapy
2. CRT device in place for \> 4 months
3. Non-responder (ejection fraction improvement with CRT \< 5%) or incomplete responder (ejection fraction \< 40%)
4. Suboptimal electrical wavefront fusion at current CRT programming as observed on 12-lead ECG
5. Left bundle branch block, interventricular conduction delay or right ventricular paced underlying QRS complex
6. Age \> 18 years

Exclusion Criteria:

1. Decompensated heart failure
2. Right bundle branch block
3. Pregnancy or lactation
4. History of severe allergic reactions to ECG gels, electrode adhesives, and/or cardiac magnetic resonance contrast (e.g. gadolinium)
5. Implantation of pacing lead in the his bundle or left bundle branch
6. Frequent ventricular ectopy as defined as \>10% premature ventricular contraction burden by either device interrogation or Holter monitor, or sustained ventricular tachycardia/ventricular fibrillation
7. Uncontrolled atrial fibrillation (HR \> 100 bpm)
8. Patient is enrolled in concurrent research study that would potentially confound the results of this study (noting: co-enrollment acceptable if patient is enrolled in registry study)