Usefulness of ventricular dyssynchrony measured using M-mode echocardiography to predict response to resynchronization therapy.

There are discordant data about the utility of septal-to-posterior wall motion delay (SPWMD) assessed using M-mode echocardiography to predict an improvement with cardiac resynchronization therapy (CRT). Baseline SPWMD was measured using M-mode in a parasternal short-axis view in a series of 67 patients undergoing CRT and followed up after 6 months. Heart failure was caused by coronary artery disease in 27 patients. Clinical responders were patients who were alive, had not undergone heart transplantation, and also increased the distance walked in 6 minutes by >10%. Baseline SPWMDs were mean 155 +/- 113 ms and median 135. Thirty-four patients (51%) had an SPWMD >130 ms. At 6-month follow-up, there were 17 nonresponders. At baseline, there were no significant differences between patients with SPWMD >130 or <130 ms in age, drug therapy, permanent atrial fibrillation, New York Heart Association functional class, underlying cause of cardiomyopathy, QRS duration, left ventricular (LV) ejection fraction, LV dimensions, or neurohormonal activation (norepinephrine and atrial and brain natriuretic peptide). At 6-month follow-up, baseline SPWMD was not associated with clinical response, New York Heart Association functional class, distance walked in 6 minutes, LV reverse remodeling, or neurohormonal activation. SPWMD >130 ms was also not a predictor. In conclusion, SPWMD is not a good predictor of response to CRT.