Relation of mechanical dyssynchrony with underlying cardiac structure and performance in chronic systolic heart failure: implications on clinical response to cardiac resynchronization.

AIMS: The aim of this study is to describe the relationship between ventricular mechanical dyssynchrony (VMD) and echocardiographic indices of cardiac remodelling. METHODS AND RESULTS: We evaluated 219 ambulatory patients with chronic systolic heart failure [left ventricular ejection fraction (LVEF) 40 ms and/or inter-VMD > 38 ms). In our study cohort, 59% of patients had evidence of dyssynchrony (including 44% with intra-VMD and 38% with inter-VMD, and 20% with both). Inter-VMD correlated with QRS width (r = 0.48, P < 0.0001) better than intra-VMD (r = 0.24, P < 0.001). Higher inter-VMD was associated with less restrictive filling patterns (rank sums P = 0.012) and larger left ventricular end-diastolic dimension (LVEDD, rank sums P = 0.020), but intra-VMD values were similar across diastolic stages and LVEDD tertiles. CONCLUSION: In chronic systolic heart failure, evidence of mechanical dyssynchrony is prevalent but the underlying cardiac structure and performance may influence the degree of inter-VMD more so than intra-VMD. Our data suggest that the extent of inter-VMD is directly related to the degree of dilatation of the heart but inversely to diastolic dysfunction.