title: A reduction in the correlation dimension of heartbeat intervals precedes imminent ventricular fibrillation in human subjects.
abstract: Reduced reflexive control of heartbeat intervals occurs with advanced heart disease and is an independent risk factor for mortality. Based on a previous study of experimental myocardial infarction in pigs, we hypothesized that a deterministic measure of heartbeat dynamics, the correlation dimension of R-R intervals (D2), may be a better predictor of risk than a stochastic measure, such as the standard deviation (SD). We determined the point estimates of the heartbeat D2 (i.e., PD2s) in Holter electrocardiographic recordings from 11 high-risk patients who manifested ventricular fibrillation (VF) during the recording and in high-risk controls having only nonsustained ventricular tachycardia (14 patients) or premature ventricular complexes (13 patients). We found that PD2 reduction (i.e., PD2s < 1.2) precedes lethal arrhythmias by hours, but is not reduced in high-risk controls (p < 0.001; sensitivity, 91%; specificity, 85%). Heartbeat SD did not discriminate among the patients. Thus PD2 of heartbeat intervals may provide an important diagnostic test and early warning sign of VF.
authors.affiliation: Department of Neurology, Baylor College of Medicine, Houston, TX.
authors.forename: J E
authors.initials: JE
authors.lastname: Skinner
authors.forename: C M
authors.initials: CM
authors.lastname: Pratt
authors.forename: T
authors.initials: T
authors.lastname: Vybiral
mesh_terms: D000465:Algorithms; D005117:Cardiac Complexes, Premature / Q000453:epidemiology; D016757:Death, Sudden, Cardiac / Q000453:epidemiology; D015716:Electrocardiography, Ambulatory; D005260:Female; D006339:Heart Rate / Q000502:physiology*; D006801:Humans; D008297:Male; D008875:Middle Aged; D011237:Predictive Value of Tests; D012307:Risk Factors; D012680:Sensitivity and Specificity; D012815:Signal Processing, Computer-Assisted; D013318:Stroke Volume / Q000502:physiology; D017180:Tachycardia, Ventricular / Q000453:epidemiology; D013997:Time Factors; D014693:Ventricular Fibrillation / Q000175:diagnosis / Q000453:epidemiology*