Excitation and Contraction of the Failing Human Heart In Situ and Effects of Cardiac Resynchronization Therapy: Application of Electrocardiographic Imaging and Speckle Tracking Echo-Cardiography

Despite the success of cardiac resynchronization therapy (CRT) for treating heart failure (HF), rate nonresponders remains 30%. Improvements to CRT require understanding reverse remodeling and relationship between electrical mechanical measures synchrony. The objective was utilize electrocardiographic imaging (ECGI, a method noninvasive electrophysiology mapping) speckle tracking echocardiography (STE) study physiology HF induced by CRT. We imaged 30 patients (63% male, mean age 63.7 years) longitudinally using ECGI STE. quantified CRT-induced electromechanical parameters evaluated novel index, delay (EMD, from activation peak contraction). also measured dyssynchrony STE compared their effectiveness predicting response EMD values were elevated in controls. However, dependent on sequence (CRT-paced vs. un-paced), indicating that is not intrinsic local tissue, but influenced factors such as opposing wall contractions. After 6 months CRT, had increased contraction native rhythm baseline pre-CRT (baseline: −8.55%, months: −10.14%, p = 0.008). They prolonged repolarization at location LV pacing lead. lateral RV time best predictor beneficial reduction end systolic volume (Spearman’s Rho: −0.722, < 0.001); it outperformed indices 12-lead ECG criteria. have abnormal EMD. depends upon predictive ECGI-measured an effective index patient selection. causes persistent improvements contractile function.