Imaging Study of Allocation of Pacing Targets in Cardiac Resynchronization Therapy

Magnetic Resonance Image guided delivery of Left and Right Ventricular Leads to optimal myocardial targets will result in improved clinical response to CRT using Left Ventricular remodeling criteria.

Cardiac Dyssynchrony and scar are important variables for realization of clinical response to cardiac resynchronization therapy (CRT). Results from a previous study suggest that paced heart segment characteristics do predict this response and our ability to identify venous pathways to optimal segments is feasible using cardiac CT and MRI. In an ongoing feasibility study we are using these capabilities to guide the delivery of CRT lead systems to optimal myocardial targets. A computer software program has been developed that can create an interactive, 3D integrated cardiac model of coronary vein anatomy, myocardial scar and mechanical dyssynchrony. Although this feasibility study is ongoing, early results show this method of guiding the CRT leads to optimal targets with these individualized models to be safe and effective. This trial will be a larger multi-centre randomized blinded trial to determine the therapeutic impact of MRI guided Left Ventricular and Right Ventricular lead placement with respect to improving clinical response rates for CRT.

Patients will be blindly randomized to image guided delivery of pacing leads during cardiac resynchronization therapy device implantation (study arm) versus standard implantation of pacing leads during cardiac resynchronization therapy device implantation (control arm).

Patients will be blindly randomized to standard implantation of pacing leads during cardiac resynchronization therapy device implantation (control arm).

Patients will be blindly randomized to image guided delivery of pacing leads during cardiac resynchronization therapy device implantation (study arm).

Patients will be blindly randomized to standard implantation of pacing leads during cardiac resynchronization therapy device implantation (control arm).

Determination of response to image guided placement of cardiac ventricular pacing leads in cardiac resynchronization therapy (CRT)

Cardiac Resynchronization Therapy (CRT) response will be defined as a change in the Left Ventricular Ejection Fraction measured at 6 months post CRT device implant by MUGA ( cardiac wall motion study) scan.

To determine if image guided lead delivery will result in a higher rate of lead delivery to optimal myocardial segments.

Cardiac CT scan will be performed at 3 months post CRT device implantation to determine secondary outcome listed above. The left ventricular (LV) lead site will be assessed for targets of dysychronous myocardium and proximity to scar tissue. The right ventricular (RV) lead will be assessed for proximity to scar tissue.

Inclusion Criteria: Age ≥ 18 years. Ejection fraction ≤ 35 %. QRS duration ≥ 120 msec. NYHA class II-IV. On maximum tolerated heart failure medication therapy ≥ 6 weeks. Clinically accepted for CRT device implantation. Exclusion Criteria: Failure to provide consent. CCS class III-IV angina. Recent Q-wave myocardial infarction or revascularization procedure ( ≤ 3 months). Standard contra-indications to MRI. Documented severe allergy to intravenous contrast dye ( iodinated CT contrast or Gadolinium MRI contrast). Estimated Glomerular Filtration Rate (eGFR) ≤ 45 ml/min/m2. Patient is pregnant.

Laksman Z, Yee R, Stirrat J, Gula LJ, Skanes AC, Leong-Sit P, Manlucu J, McCarty D, Turkistani Y, Scholl D, Rajchl M, Goela A, Islam A, Thompson RT, Drangova M, White JA. Model-based navigation of left and right ventricular leads to optimal targets for cardiac resynchronization therapy: a single-center feasibility study. Circ Arrhythm Electrophysiol. 2014 Dec;7(6):1040-7. doi: 10.1161/CIRCEP.114.001729. Epub 2014 Sep 14.