Prognostic value of QT/RR slope in predicting mortality in patients with congestive heart failure.
BACKGROUND
Repolarization dynamics, reflecting adaptation of QT to changing heart rate, is considered a marker of unfavorable prognosis in patients with heart diseases. We aimed to evaluate the prognostic value of QT/RR slope in predicting total mortality (TM) and sudden death (SD) in patients with congestive heart failure (CHF).


RESULTS
In 651 sinus rhythm patients with CHF in NYHA class II-III enrolled in the MUSIC study, 24-hour Holter monitoring was performed at enrollment to assess slope of the QTa/RR (QT apex) and QTe/RR (QTend) during the entire 24-hour Holter recording and separately during day and night periods. Patients were followed for a median of 44 months, with the primary endpoint defined as TM and the secondary as SD. Analysis of repolarization dynamics was feasible in 542 patients (407M), mean age 63 years, 83% in NYHA class II, 49% with ischemic cardiomyopathy, with mean LVEF 37%. Mean value of QTa/RR slope was 0.172 and QTe/RR was 0.193. During the 44-month follow-up there were 119 deaths including 47 SD. Nonsurvivors were characterized by steeper QT/RR slopes. Increased QT/RR slopes during the daytime (>0.20 for QTa and >0.22 for QTe) were independently associated with increased TM in multivariate analysis after adjustment for clinical covariates with respective hazard ratios 1.57 and 1.58, P = 0.002. None of the dynamic repolarization parameters was associated with increased risk of SD in the entire population.


CONCLUSIONS
Abnormal repolarization dynamics reflected as increased daytime QT/RR slopes is an independent risk stratifier of all-cause mortality in patients with chronic heart failure.
Institut Català Ciències Cardiovasculars, Barcelona, Spain; and Heart Research Follow-up Program, University of Rochester, Rochester New York, USA.
Iwona
I
Cygankiewicz
Wojciech
W
Zareba
Rafael
R
Vazquez
Jesus
J
Almendral
Antoni
A
Bayes-Genis
Miquel
M
Fiol
Mariano
M
Valdes
Carlos
C
Macaya
Jose R
JR
Gonzalez-Juanatey
Juan
J
Cinca
Antoni
A
Bayes de Luna
D017677:Age Distribution; D000368:Aged; D003936:Diagnosis, Computer-Assisted / Q000379:methods* / Q000706:statistics & numerical data; D015716:Electrocardiography, Ambulatory / Q000379:methods* / Q000706:statistics & numerical data; D005260:Female; D006333:Heart Failure / Q000175:diagnosis* / Q000401:mortality*; D006801:Humans; D015994:Incidence; D008297:Male; D008875:Middle Aged; D011379:Prognosis; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D017678:Sex Distribution; D013030:Spain / Q000453:epidemiology; D016019:Survival Analysis; D015996:Survival Rate