title: Prediction of left ventricular peak ejection velocity by preceding and prepreceding RR intervals in atrial fibrillation: a new method to adjust the influence between two intervals.
abstract: In atrial fibrillation, cardiac performance is dependent on both preceding RR (RR-1) and prepreceding RR (RR-2) intervals. However, relative contributions were not well defined. Left ventricular outflow peak ejection velocity (Vpe) was measured by echocardiography from 21 patients. The relation between RR-1 and Vpe could be divided into two zones; steep slope in short RR-1 intervals (< or =0.5 sec) and plateau in long RR-1 intervals (> 0.5 sec). RR-2 had a weak negative association with Vpe. The mean squared correlation coefficient (r2) between RR-2 and Vpe was 0.15 +/-0.13 and improved to 0.29+/-0.21 (p<0.001), when coordinates with RR-1 < or =0.5 sec were excluded. The RR-1 was positively associated with Vpe. The mean r2 between RR-1 and Vpe was 0.52+/-0.17 and improved to 0.72+/-0.11 (p<0.001), when adjusted by RR-2. Simple linear regression analysis showed that mean RR interval, age, fractional shortening (FS), and mean peak velocity were negatively correlated with modified r2 between RR-2 and Vpe. Multiple stepwise regression analysis revealed that mean RR interval (r2=0.32) and FS (r2=0.16) were significant. In summary, simple modification could improve the relationship of both RR-1 and RR-2 with cardiac performance. RR-2 might play a more role in cardiac performance than previously expected, and when cardiac function was impaired.
authors.affiliation: Division of Cardiology, Department of Internal Medicine, College of Medicine, Chung-Ang University, Seoul, Korea. cjkim@cau.ac.kr
authors.forename: Hong Sook
authors.initials: HS
authors.lastname: Ko
authors.forename: Kwang Je
authors.initials: KJ
authors.lastname: Lee
authors.forename: Sang Wook
authors.initials: SW
authors.lastname: Kim
authors.forename: Tae Ho
authors.initials: TH
authors.lastname: Kim
authors.forename: Chee Jeong
authors.initials: CJ
authors.lastname: Kim
authors.forename: Wang Seong
authors.initials: WS
authors.lastname: Ryu
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D001281:Atrial Fibrillation; D016279:Atrial Function, Left; D018619:Echocardiography, Doppler, Pulsed / Q000379:methods*; D004554:Electric Countershock; D004562:Electrocardiography / Q000379:methods*; D005260:Female; D006321:Heart / Q000502:physiology*; D006352:Heart Ventricles; D006801:Humans; D008297:Male; D008875:Middle Aged; D009206:Myocardium / Q000473:pathology; D013997:Time Factors