Response To Cardiac Resynchronization Therapy In Heart Failure: Role Of Arterial Stiffness

The patients receiving CRT are medically refractory, symptomatic, NYHA class III or IV disease and QRS duration of 130 m sec or greater, and a left ventricular ejection fraction of 30 percent or less.

The pulse wave velocity between carotid and femoral (PWVcf) will be recorded in each subject at base line (before and after CRT), at one month (after AV delay optimization) and again at 6 months after CRT. The arterial pulse wave is recorded at a proximal artery, such as the carotid artery, and as well as at a distal artery, such as the femoral artery. The superficial location of the carotid and femoral arteries means that their pulse waveforms are readily measured noninvasively using the M Hz Doppler probe, and between these two sites the pulse wave has to travel through most of the aorta. The time delay between the arrival of a predefined part of the pulse wave, such as the foot, at these 2 points is obtained by gating to the peak of the R-wave of the ECG. The distance traveled by the pulse wave is measured over the body surface and PWV is then calculated as distance/time (m/s).

Clinical evidence of response: Either one or more of the following: 1) Improvement in NYHA functional classification, 2) Improvement in 6 minute walking distance. 3) Change in functional class, exercise tolerance while the heart is getting smaller on CXR. 4) Stabilization of patient CHF even without subjective improvement over 6 months (remaining class III rather than progressive to class IV). Imaging evidence of response: 1) Increase in left ventricular ejection fraction. 2) Reduction of mitral regurgitation. 3) Reduction of LV volume signifying reverse remodeling.