RR Interval Dynamics Before Atrial Fibrillation in Patients After Coronary Artery Bypass Graft Surgery

Abstract

Background-Atrial fibrillation/flutter (AF) is a frequent complication of coronary artery bypass graft surgery (CABG) that leads to increased costs and morbidity. We hypothesized that heart rate variability (HRV), an indicator of cardiac sympathovagal balance, is altered before the onset of postoperative AF. Because nonlinear methods of HRV analysis provide information about heart rate dynamics not evident from usual HRV measures, we also hypothesized that approximate entropy (ApEn), a nonlinear measure of HRV, might have predictive value. Methods and Results-Analysis of HRV was performed in 3 sequential 20-minute intervals preceding the onset of postoperative AF (24 episodes in 18 patients). These data were compared with corresponding intervals in 18 sex-and age-matched postoperative control subjects who did not develop AF. Patients had left ventricular ejection fractions Ͼ45% before surgery and were not receiving ␤-blockers during ambulatory ECG monitoring after surgery. Logistic regression demonstrated that on the basis of averaged values for the three 20-minute intervals, increased heart rate and decreased ApEn were independently associated with AF. Heart rate dynamics before AF was associated with either lower (nϭ19) or higher (nϭ5) RR interval variation by traditional measures of HRV or quantitative Poincaré analysis, suggesting the possibility of divergent autonomic conditions before AF onset. Conclusions-In the hour before AF after CABG surgery, higher heart rate and lower heart rate complexity compared with values in control patients were independent predictors of AF. Decreased ApEn occurs in patients with either increased or decreased HRV by traditional measures and may provide a useful tool for risk stratification or investigation of mechanisms. (Circulation. 1998;98:429-434.)

Altered Complexity and Correlation Properties of R-R Interval Dynamics Before the Spontaneous Onset of Paroxysmal Atrial Fibrillation

“…26 Concurrent with the present observations, a recent study also reported on reduced ApEn preceding spontaneous AF episodes in patients after coronary artery bypass surgery. 10 These results suggest that a reduced complexity of R-R interval dynamics is a common finding preceding the onset of AF episodes, independent of the clinical condition and cause of an underlying structural heart disease.…”

“…[13][14][15][16] A recent study suggested that altered complexity of R-R interval dynamics precedes the AF episodes of patients after coronary artery bypass graft surgery. 10 The trigger mechanisms and pathophysiology of AF may be different between patients with and without organic heart disease and in various clinical situations. The present study was designed to test the hypothesis that altered R-R interval dynamics, as analyzed by new complexity and fractal measures, may also precede the onset of paroxysmal, idiopathic AF.…”

Efeito da denervação cardíaca ventral na incidência de fibrilação atrial após revascularização cirúrgica do miocárdio

“…After coronary artery bypass grafting (CABG) the incidence of AF varies from 19 to 27% and is the most common morbidity after this surgery [2]. Thus, with the growing interest in understanding the physiopathologic basis responsible for the occurrence of this arrhythmia, operative techniques have been developed aiming at reducing its incidence [3].…”

Nonlinear Methods of Cardiovascular Physics and Their Clinical Applicability

“…No significant difference was seen in the turbulence slope between the AF and control, and none of the traditional frequency and time domain measures differentiated between both; ApEn was significantly lower before AF than during the non-AF hours (p < 0.01). Increased predictability in heart rate behavior, measured by ApEn, also has been reported to precede spontaneous episodes of ApEn after coronary artery bypass surgery [Hogue, Jr. et al, 1998] Analysis of HRV in this study was performed in three sequential 20-minute intervals preceding the onset of postoperative AF (24 episodes in 18 patients). These data were compared with corresponding intervals in 18 sex-and age-matched postoperative control subjects who did not develop AF.…”