Myocardial viability is a better than qrs duration in predicting clinical benfit from cardiac resynchronisation therapy

Although the benefits of cardiac resynchronisation therapy (CRT) are well established, they are difficult to predict from clinical, ECG or echocardiographic parameters. Gadolinium DTPA-enhanced magnetic resonance (Gd- MR) imaging is the gold-standard for the in vivo identification of myocardial scarring. This study hypothesised that the clinical benefit of CRT can be predicted from the assessment of left ventricular (LV) myocardial viability using Gd-MR. 29 patients with heart failure due to coronary heart disease or dilated cardiomyopathy, aged 71.3 (1.8) yrs [mean (SEM)], in NYHA class II (n=1), III (n=21) and IV (n=7) and with a QRS of 154 (12) ms underwent a clinical assessment, including a 6-min walk test, before and after CRT. A Gd-MR scan (1.5 TGE Signa scanner) was obtained at baseline,10 min following 0.1 mmol/Kg Gd-DTPA i.v., using a multiphase inversion recovery fast gradient recalled-echo (IR-FGRE) sequence. Scar volume was calculated by planimetry from short axis sections and expressed as a % of total LV myocardial volume. Non-responders (NR) were defined as patients who died or in whom, at the most recent follow-up, NYHA class and/or 6 min walking distance had either not changed or decreased. After a follow-up period of 418.0 (44.9) days, 6 NR were identified. % scar volume was 30.7 (8.9) cm3 in NR and 12.5 (2.0) cm3 in responders(R) (ANOVA, p=0.0041). In logistic regression analyses, % scar volume emerged as a predictor of NR (p=0.0194), whilst LV ejection fraction, baseline QRS duration and aetiology did not. In survivors, % scar volume emerged as a predictor of change in walking distance from baseline to follow-up (p=0.0337). Myocardial viability assessed by Gd-MR is a predictor of outcome in patients undergoing CRT. Further studies are needed to determine the role of Gd-MR in selecting patients for CRT.