Regular paper
Comparison of benefits from cardiac resynchronization therapy in patients with ischemic cardiomyopathy versus idiopathic dilated cardiomyopathy

https://doi.org/10.1016/j.amjcard.2003.12.024Get rights and content

Abstract

Cardiac resynchronization therapy (CRT) is a recently introduced therapeutic option for patients with severe heart failure and intraventricular conduction disturbances. However, it is estimated that 20% to 30% of patients may not respond to CRT. Patients with ischemic cardiomyopathy (IC) may respond less favorably to CRT compared with patients with idiopathic dilated cardiomyopathy (IDC). Accordingly, the beneficial effects of CRT were evaluated in 2 subsets of patients (IC and IDC). Seventy-four patients with end-stage heart failure, New York Heart Association (NYHA) class III or IV, left ventricular (LV) ejection fraction <35%, QRS >120ms, and left bundle branch block received a biventricular pacemaker. At baseline and 6 months after implantation these parameters were evaluated: NYHA class, Minnesota quality-of-life score, QRS duration, and 6-minute walking distance. LV ejection fraction and severity of mitral regurgitation were assessed before and 6 months after CRT using 2-dimensional echocardiography. Long-term follow-up and hospitalization rates were obtained up to 2 years. Of the 74 patients, 46% (n = 34) had IC and 54% (n = 40) IDC. At 6 months follow-up all clinical parameters, QRS duration, LV ejection fraction, and mitral regurgitation improved significantly in both groups. Long-term (2-year) follow-up showed a survival rate of 87.5% for patients with IDC and 88.3% for patients with IC. The percentages of responders to CRT (defined as an improvement in NYHA class ≥1 grade) were comparable in both groups (65% vs 71%). Therefore, the underlying etiology of heart failure (IC vs IDC) was not related to the response to CRT.

Section snippets

Patients and study protocol

Consecutive patients (n = 74) who received a biventricular pacemaker for congestive heart failure were included. The traditional selection criteria for CRT were applied: New York Heart Association (NYHA) class III or IV; left ventricular (LV) ejection fraction <35%; QRS duration >120 ms; and left bundle branch block morphology.1, 2, 3 Clinical evaluation was performed before pacemaker implantation and repeated after 6 months of CRT. Clinical evaluation included assessment of NYHA class,

Patient population

A total of 74 consecutive patients were included, with 40 (54%) having IDC and 34 (46%) IC. Of the patients with IC, 31 (91%) had a prior infarction (90% anterior wall, 71% with a Q wave) and the mean number of stenosed coronary arteries was 2.3 ± 1.0. The study population comprised 58 men and 16 women, with a mean age of 65 ± 11 years. According to the inclusion criteria, all patients had a wide QRS complex (177 ± 29 ms, range 120 to 220) and left bundle branch block configuration. The mean

Discussion

In line with previous observations,1, 2, 3 CRT resulted in a significant improvement in symptoms, exercise capacity (as reflected in the 6-minute walking distance), and systolic function (as expressed in LV ejection fraction). In the present study, CRT improved the 6-minute walking distance by 38% on average, comparable with the 23% shown by Cazeau et al.11 LV ejection fraction improved significantly, which is in line with previous observations by Sogaard et al,12 who showed an improvement from

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    2013, International Journal of Cardiology
    Citation Excerpt :

    In contrast, a reduced LV myocardial perfusion, as assessed with myocardial 99mTc-MIBI uptake, was reported not to be a predictor for the response of CRT in patients with HF [29]. Moreover, it has been reported that the benefit of CRT does not differ significantly between patients with ischemic cardiomyopathy and those with nonischemic cardiomyopathy [30–33]. Recent evidence has suggested that the presence of myocardial scar tissues reduces the beneficial effect of CRT because the electric stimuli for CRT may be blocked by the scar tissues, in particular those seen near the tip of the LV pacing lead [34–38].

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