Imaging synchrony

Excerpt

There are 550,000 new cases of heart failure with 1,000,000 hospitalizations and 250,000 heart failure deaths yearly in the USA with similar numbers in the European Union. Cardiac resynchronization therapy (CRT), based in the placement of A-V sequential, biventricular pacemakers, is indicated to treat patients with advanced, medically refractory heart failure, reduced left ventricular (LV) function, and prolonged QRS duration. Normally stimulated in an orderly pattern, conduction is rapid through normal myocardium, bringing near simultaneous, coordinate, and synchronous myocardial contraction. Scarring leads to irregular conduction and varied sequences of dyssynchronous contraction. CRT, seeks to improve mechanical synchrony, but has other benefits. CRT has been shown to improve symptoms and survival, increase exercise tolerance, and quality of life, reduce hospitalization, and bring reverse remodeling1 in heart failure patients. Yet, there is now nothing better to determine mechanical synchrony and the potential for CRT improvement, than ECG QRS duration, a crude and imperfect electrical surrogate for mechanical dyssynchrony which excludes many with heart failure and cannot optimize LV pacemaker placement. The current broad inclusion criteria bring variable functional improvement in only 60-70% of CRT patients.2 CRT is invasive, costly, and risky. A better indicator of CRT improvement is needed. …