Is cardiac venous anatomy a crucial factor in maximizing the response to cardiac resynchronisation therapy?

Cardiac resynchronization therapy (CRT) restores the synchrony of the heart’s contractions. The most critical issue in CRT implantation is the positioning of the coronary sinus (CS) lead because not every region can be accessed due to variations in coronary venous anatomy. The aim was to determine the correlation between different CS lead positions and hemodynamic changes and clinical outcome over time. Our study prospectively enrolled 51 patients with conventional indications for CRT which was divided into three groups according to the vein in which the left ventricle lead was placed during the procedure (posterior, lateral, and anterior). The groups were compared by baseline demographic characteristics, comorbidity, complications, new hospitalizations as well as by hemodynamic parameters before and six months after the procedure. After six months, all patients responded to CRT in the lateral group, 66.7% patients in the posterior group and 50% in the anterior group (p<0.01). Patients in the anterior group had a smaller decrease in NYHA functional class compared to the posterior and the lateral groups (p<0.01). The largest increase of preoperative ejection fraction value was in the posterior group (68.7%) compared to the lateral (42.2%) and anterior groups (19.8%) (p<0.01, A vs. P&L; P vs. A&L). In the anterior group there was a smaller decrease of QRS complex compared to the posterior and lateral groups (p< 0.05, A vs. P&L). Also there was a smaller decrease in the degree of mitral regurgitation in the anterior group compared to the lateral and posterior groups (p<0.05, A vs. P&L). One of the main determinants of CRT response is the anatomy of CS tributaries, and therefore the position of the LV lead is crucial in maximizing the effect of CRT