Relationship of left atrial mechanics to electrical activity on surface electrocardiography in idiopathic dilated cardiomyopathy.

Aim: (1) Assess left atrial (LA) mechanics and electromechanical delay in patients with idiopathic dilated cardiomyopathy (IDCM), and (2) examine the relationship between atrial electromechanical delay and atrial electrical activity [P-wave duration, P-wave dispersion (PWD) and P terminal force (PTF)] on surface ECG. Methods: 73 IDCM patients (age 36  ±  17 years); 63% men,25 age & sex matched healthy subjects were studied. LA atrial electromechanical delay & mechanics (ε(sys), SR(sys), SR(e), SR(a)) were measured with 2D-strain. From 12-lead electrocardiograms, P-wave duration, PWD and PTF calculated. Results: Reservoir, conduit and contractile functions were predominantly reduced compared to control (P < 0.001). Intra-atrial electromechanical delay was 88.9 ± 84.6 in IDCM versus 27.4 ± 16.5 in control (P < 0.0001). In IDCM, PWD (52.89 ± 15), P(max)(98 ± 17.5) and PTF(58.2 ± 36) were significantly increased compared to control (36.20 ± 8.9, 79 ± 9.9, 25.22 ± 8.76) respectively (P < 0.0001). A positive correlation was detected between intra-atrial electromechanical delay and PWD &PTF (r = 0.5, P < 0.0001). By stepwise multiple linear regression analyses, LA reservoir function (LA ε(sys)) [β = 0.754; CI at 95%:0.356-0.780, P < 0.001] and LA volume [β = 0.743; CI 95%:0.423-0.75, P < 0.001], and PWD [β=0.848; CI 95%:0.311-0.644, P < 0.0001], and PTF [β = 0.927; CI 95%: 0.357-0.722, P < 0.0001] are independent predictors for LA electromechanical delay in IDCM. Conclusion: In addition to altered LA mechanics, atrial electromechanical delay gets longer in IDCM and is correlated with PWD and PTF. Atrial electrical dispersion on surface ECG could be early index of LA dysfunction that deserves further study.