Cor Vasa 2010, 52(1-2):43-48 | DOI: 10.33678/cor.2010.009

The importance of ventricular dyssynchrony in predicting the response to cardiac resynchronization therapy

Rudolf Praus^1,*, Miloslav Tauchman¹, Luděk Haman¹, Václav Bláha², Petr Pařízek¹

¹ I. interní klinika, Fakultní nemocnice Hradec Králové a Lékařská fakulta v Hradci Králové Univerzity Karlovy v Praze, Hradec Králové

² Katedra veřejného zdravotnictví, Fakulta vojenského zdravotnictví Univerzity obrany, Hradec Králové, Česká republika

Aim: The aims of this prospective study were to define the numbers of responders and non-responders to cardiac resynchronization therapy (CRT) and differences between these groups, and to assess the development of clinical and echocardiographic effects of CRT in the group of responders over a period of time.
Group of patients and methods: A total of 58 patients with a biventricular system implanted from July 2005 through May 2008 were included into the follow-up. The mean age of patients was 67 ± 9 years; they were classified in NYHA Class IV (one patient), III-IV (18 patients), III (23 patients), and II (three patients), with average QRS duration 193 ± 33 ms, and the diagnosis of dilated cardiomyo-pathy (22 patients), coronary artery disease (33 patients), or the presence of both (three patients). At baseline, and three and 15 months after the implantation, the following parameters were assessed: NYHA class, quality of life (QOL) as measured by the Minnesota Living with Heart Failure (MLHF) questionnaire, 6-minute walk test (6MWT), echocardiography including inter- and intraventricular dyssynchrony, dP/dt, and ventricular outflow tract velocity-time integral (VTILVOT). A responder was defined as a patient who had improved in QOL, NYHA class and/or 6MWT by more than 10%.

Results: Fifteen months after CRT initiation, there were 38 responders (66%) and 19 non-responders (33%). The groups differed only in the extent of ventricular dyssynchrony, with responders showing statistically more significant signs of interventricular dyssynchrony [interventricular mechanical delay (IVMD) 62.1 ± 23.1 ms in responders vs. 46.8 ± 30.3 ms in non-responders; p < 0.05] and intraventricular dyssynchrony [the delay between time to peak systolic velocity in the ejection phase in basal septal and basal lateral segments (Ts-lateral-septal) was 71.2 ± 32.0 ms in responders vs. 48.4 ± 29.2 ms in non-responders; p < 0.05]. Statistically significant changes in all monitored parameters in the group of responders occurred as early as three months after CRT initiation. Additional significant changes between months 3 and 15 of follow-up were seen only in three echocardiographic parameters [left ventricular ejection fraction (LVEF) improved from 27.1 ± 9.8% to 32.8 ± 12.5%, p < 0.001), left ventricular end-diastolic diameter (LVEDD) decreased from 66.1 ± 8.3 mm to 64.0 ± 8.1 mm; p < 0.05, and VTI LVOT increased from 16.7 ± 4.1 cm to 18.8 ± 4.4 cm; p < 0.001]. No other statistically significant changes were observed.

Conclusion: Fifteen months after CRT initiation, there were 38 responders (66%) and 19 non-responders (33%) in our series, i.e. numbers similar to those reported in the relevant literature. These groups differ only in the extent of ventricular dyssynchrony before the implantation of a biventricular system. Statistically significant changes in all monitored parameters were observed in the group of responders as early as three months after CRT initiation.

Keywords: Heart failure; Cardiac resynchronization therapy; Ventricular dyssynchrony

Published: January 1, 2010  Show citation