Right Ventricular Function Correlates with Local Mechanical Dyssynchrony of Interventricular Septum in Patients with Non-Ischemic Dilated Cardiomyopathy

Abstract

The underlying mechanisms of right ventricular (RV) dysfunction in patients with non-ischemic dilated cardiomyopathy (NICM) remain poorly defined. We evaluated a potential correlation between local mechanical dyssynhcrony of interventricular septum (IVS) and RV function in these patients. We analyzed electromechanical data of 30 NICM patients with NYHA class III, and left ventricular ejection fraction (LVEF) <40% undergoing CD34+ cell therapy. All patients received granulocyte-colony stimulating factor for 5 days; CD34+ cells were collected by apheresis and injected transendocardially. At baseline, and at 6 months after therapy we performed electromechanical mapping and echocardiography. Local mechanical dyssynchrony of IVS was defined as a temporal difference between global and segmental peak systolic displacement normalized to the average duration of the RR interval on electromechanical mapping. Using echocardiography, RV function was assessed by tricuspid annular plane systolic excursion (TAPSE), peak systolic velocity of tricuspid annulus (St), and fractional area change (FAC). RV dysfunction was defined as TAPSE <1.7 cm, St <9.5 cm/s, and FAC< 35%. At baseline, RV function was impaired in 19 patients (63%, Group A), and preserved in 11 patients (37%, Group B). The two groups did not differ in age (54±10 years in Group A vs. 53±9 years in Group B, P=0.62), sex (male: 84% vs. 82%, P=0.87), creatinine (0.86±0.25 mg/dL vs. 0.89±0.31 mg/dL, P=0.60), bilirubin (0.91±0.25 mg/dL vs. 0.82±0.34 mg/dL, P=0.25), LVEF (32.5±9.4% vs. 34.9±8.3%, P=0.29), or NTproBNP levels (1467±1057 pg/mL vs. 1195±1175 pg/mL, P=0.30). On baseline electroanatomical mapping, local mechanical dyssynchrony of IVS was significantly higher in Group A than in Group B (25.7±8.8 % vs. 16.9±9.5 %, P=0.001). In Group A, we found an improvement in RV function at 6 months after cell therapy (TAPSE: +0.33±0.54 cm, P=0.01; St: +1.3±2.1 cm/s; P=0.02; FAC: +9.2±2.3%, P=0.01). In parallel with RV improvement, we observed a significant decrease in IVS dyssynchrony (-10.2±5.2 %). RV function in NICM patients correlates with local mechanical dyssynchrony of IVS. Transendocardial CD34+ cell therapy appears to be associated with decreased IVS dyssynchrony and improved RV function in this patient population.