The promise of resynchronization therapy. Who (and how many) will benefit?

It has been estimated that about 320,000 to 400,000 patients in the USA alone are possible candidates to cardiac resynchronization therapy according to the recently published AHA/ACC/NASPE guidelines for pacing and the results of the COMPANION trial. The selection of the most suitable candidate for CRT/CRTD is a crucial issue, but still a matter of debate. A large variety of clinical, invasive and non-invasive criteria have been proposed for appropriately selecting candidates for CRT.

Effect of cardiac resynchronization therapy on ventricular remodeling.

Cardiac resynchronization therapy (CRT) is a new non-pharmacological option for patients with advanced heart failure and ventricular conduction delay. Four randomized prospective studies have provided evidence that CRT increases exercise capacity, improves functional class and quality of life. There is also increasing evidence that CRT may trigger an inverse remodeling process leading to reduction of ventricular diameter and eventually of the atrial size.

Cardiac resynchronization therapy restores optimal atrioventricular mechanical timing in heart failure patients with ventricular conduction delay.

We characterized the relationship between systolic ventricular function and left ventricular (LV) end-diastolic pressure (LVEDP) in patients with heart failure (HF) and baseline asynchrony during ventricular stimulation. The role of preload in the systolic performance improvement that can be obtained in HF patients with LV stimulation is uncertain.We measured the maximum rate of increase of LV pressure, LVEDP, aortic pulse pressure (PP) and the atrioventricular mechanical latency (AVL) between left atrial systole and LV pressure onset in 39 patients with HF.