Patterns of ventricular dyssynchrony in congestive heart failure- comparison with controls and implications for patient selection for cardiac resynchronization therapy.

BACKGROUND

Assessment of ventricular dyssynchrony by Tissue Doppler Imaging (TDI) is being increasingly used in patient selection for Cardiac Resynchronization Therapy (CRT). Regional distribution of dyssynchrony has been sparingly addressed in dyssynchrony studies in heart failure population.

METHODS

TDI was used to assess prevalence and regional distribution patterns of ventricular dyssynchrony in heart failure (HF) patients with systolic LVdysfunction (LVEF equal or less than 40%) in sinus rhythm. Inter-ventricular dyssynchrony (IVD) and left ventricular dyssynchrony (LVD) equal or greater than 40 msec were considered significant and LVD equal or greater than 65 m sec indicated severe dyssynchrony.

RESULTS

100 HF patients (Wide QRS, Gp I, N =70 & Normal QRS Gp II, N=30, and 25 normal individuals with complete LBBB (n=14) or RBBB (n=11) underwent TDI. IVD was seen in 35 (35%) patients (74% LV delay & 26% RV delay) and LVD in 68 patients (68%). The relative prevalence of lVD and LVD respectively in Group land Group II HF patients was47% vs. 7% (p < 0.001) and 70% vs. 67%. (p=ns) while LVD in Groups A (LBBB, n=41) & B (RBBB, n=26) was 76% and 58%, p=ns. The prevalence ofsevere LVD was similar in Gp I & II (37% and 57%, p=ns), and in Gp A & B (46% & 26%, p=ns). Regional distribution patterns of LVD in normal individuals with bundle branch block showed septal delay in 20%, a prevalence of similar to heart failure population (23%, Gp I, and 21% Gp II, p=ns). Lateral wall delay was demonstrated only in the HF population seen in 33% of Gp I and 47% of Gp II patients, p=ns.

CONCLUSIONS

LVD is distributed amongst HF patients with narrow or wide QRS and with LBBB or RBBB with a similar regional distribution. Dyssynchrony in normal individuals with bundle branch block is in the form of septal delay. These findings may have implications for patient selection for CRT and site of LV pacing.