title: Characterization of QT interval adaptation to RR interval changes and its use as a risk-stratifier of arrhythmic mortality in amiodarone-treated survivors of acute myocardial infarction.
abstract: A new method is proposed to evaluate the dynamics of QT interval adaptation in response to heart rate (HR) changes. The method considers weighted averages of RR intervals (RR) preceding each cardiac beat to express RR interval history accounting for the influence on repolarization duration. A global optimization algorithm is used to determine the weight distribution leading to the lowest regression residual when curve fitting the [QT, RR1 data using a patient-specific regression model. From the optimum weight distribution, a memory lag L90 is estimated, expressing the delay in the QT adaptation to HR changes. On average, RR intervals of the past 150 beats (approximately 2.5 min) are required to model the QT response accurately. From a clinical point of view, the interval of the initial tens of seconds to one minute seems to be most important in the majority of cases. A measure of the optimum regression residual (r(opt)) has been calculated, discriminating between post-myocardial infarction patients at high and low risk of arrhythmic death while on treatment with amiodarone. A similar discrimination has been achieved with a variable expressing the character of QT lag behind the RR interval dynamics.
authors.affiliation: Communications Technology Group (GTC), Aragón Institute for Engineering Research (13A), University of Zaragoza, 50018 Zaragoza, Spain. epueyo@unizar.es
authors.forename: Esther
authors.initials: E
authors.lastname: Pueyo
authors.forename: Peter
authors.initials: P
authors.lastname: Smetana
authors.forename: Pere
authors.initials: P
authors.lastname: Caminal
authors.forename: Antonio Bayes
authors.initials: AB
authors.lastname: de Luna
authors.forename: Marek
authors.initials: M
authors.lastname: Malik
authors.forename: Pablo
authors.initials: P
authors.lastname: Laguna
mesh_terms: D000222:Adaptation, Physiological; D000465:Algorithms; D000638:Amiodarone / Q000627:therapeutic use; D000889:Anti-Arrhythmia Agents / Q000627:therapeutic use; D015984:Causality; D015897:Comorbidity; D003936:Diagnosis, Computer-Assisted / Q000379:methods*; D015716:Electrocardiography, Ambulatory / Q000145:classification / Q000379:methods*; D006339:Heart Rate; D006801:Humans; D009203:Myocardial Infarction / Q000175:diagnosis* / Q000188:drug therapy / Q000401:mortality*; D015203:Reproducibility of Results; D018570:Risk Assessment / Q000379:methods*; D012307:Risk Factors; D012680:Sensitivity and Specificity; D016019:Survival Analysis; D017741:Survivors; D016896:Treatment Outcome; D014693:Ventricular Fibrillation / Q000175:diagnosis* / Q000188:drug therapy / Q000401:mortality*
chemical_list: D000889:Anti-Arrhythmia Agents; D000638:Amiodarone