Cardiac resynchronization therapy when no lateral pacing option exists: vectorcardiographic guided non-lateral left ventricular lead placement predicts acute hemodynamic response

Aims A difficult cardiac resynchronization therapy (CRT) implantation scenario emerges when no lateral pacing option exists. The aim of this study was to explore the effect of biventricular pacing (BIVP) on vectorcardiographic parameters in patients with a non-lateral left ventricular (LV) lead position. We hypothesized that perimeter and area reduction for both the QRS complex and T-wave would predict acute CRT response.Methods and results Twenty-six patients (14 ischaemic) with a mean age of 63 +/- 10 years and standard CRT indication underwent device implantation with continuous LV pressure registration. The LV lead was placed in either an anterior or apical position. Biventricular pacing was performed at a rate 10% above intrinsic rhythm with acute CRT response defined as LV Delta dP/dt(max) >10%. Using this criterion 12 patients were identified as acute CRT responders (responders: 16.7 +/- 4.8% vs. non-responders: 1.9 +/- 5.3%, P<0.001). Vectorcardiographic assessment of the QRS complex and T-wave were performed at baseline and under BIVP. Based on the observed changes in three-dimensional area and perimeter, Delta QRS-area (responders: -46.7 +/- 39.6% vs. non-responders: 1.1 +/- 50.9%, P=0.006) was considered as the preferred parameter. Receiver operating characteristic curve analysis identified -40% as the optimal cut-off value (sensitivity 67% and specificity 93%) for prediction of acute CRT response (AUC = 0.81, P < 0.01). A significant correlation was observed between LV Delta dP/dt(max) and Delta QRS-area (R-2 =0.37, P=0.001).Conclusion Delta QRS-area is correlated to LV Delta dP/dt(max) and predicts acute CRT response in patients with a non-lateral LV lead position. Assessment of Delta QRS-area might be a useful tool for patient specific LV lead placement when no lateral pacing option exists.