Sympathetic overactivity increases the risk of ventricular arrhythmias. Previous studies showed that alteration of QT dynamicity, reflecting abnormal sympathetic modulation of ventricular repolarisation, is independently predictive of sudden cardiac death among patients with chronic heart failure. The aim of this study was to determine whether impaired adaptation of the QT interval to changes in heart rate also predicts death at one month in patients with acute heart failure.
In this study, we prospectively included 99 patients (mean age 71+/-13 years) with acute heart failure (EF=35,2±13,4 %, BNP=1045±83 pg/ml). Heart rate variability and QT dynamicity was evaluated by analyzing 24-h Holter recordings. The linear regression slope of QT interval measured to the apex and to the end of T wave plotted against RR intervals was calculated using dedicated Holter algorithm. Clinical, biological and morphological data were collected. Follow-up was performed by direct examination or.
After a follow up of one month 21 patients died. Non survivors were older (76+/8 vs. 69±15 years, p<0,05), had signifi cantly decreased ejection fraction (28,8±12,7 % vs. 36,9±13,1 %, p<0,05), lower hemoglobin levels (11,4±1,7g/dl vs. 12,5±2,3g/dl, p<0,05) and red blood cells (3650±458 1000/μl vs. 4287±771 1000/μl, p<0,05). Among parameters issued from 24-h Holter-EKG analysis only day QTe slope was signifi cantly decreased in non survivors (0,33±0,23 vs 0,56±0,64, p<0,05).
These results suggest that clinical, biological and electrical parameters issued from 24hours Holter-ECG recording are able to predict short term mortality in patients with acute heart failure. These preliminary results need to be confirmed by a more extensive statistical approach currently ongoing. These predictive parameters are simple to use and their clinical or pharmacological interest need to be confirmed.
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