title: R/S Ratio Variability in Lead V1 Observed between Selected Four 1-Minute ECG Fragments of 24-Hour ECG as a Predictor of Incomplete Resynchronization during Full 24-Hour ECG: Pilot Study.
abstract: BACKGROUND
  About 30% of patients do not have an effective cardiac resynchronization therapy (CRT). Routine assessment of CRT by devices interrogation (DI) is not entirely reliable. Additional information provide detailed QRS analysis in 24-hour ECG, however it is time-consuming. The aim of the study was the assessment of R/S ratio variability in lead V1 between selected fragments of 24-hour ECG as a predictor of incomplete biventricular pacing (BIVP) during full 24-hour ECG.
  
  
  METHODS
  The 12-lead 24-hour ECGs of 43 patients with sinus rhythm were studied. During 24-hour ECG the 6-minute walk test (6MWT) was performed. The CRT was assessed by analyzing DI and full 24-hour ECG and four 1-minute fragments of these ECG recordings: during the minimum and the maximum heart rate and at the 1st and last minute of 6MWT.
  
  
  RESULTS
  During DI the effective (>95%) BIVP was present in 36 patients (83.7%). Analysis of full 24-hour ECG confirmed appropriate BIVP in 31 patients (72%) and suspected incomplete BIVP (≤95%) in 12 patients (28%). In 9/12 patients the R/S ratio variability in lead V1 was visible between selected ECG fragments of 24-hour ECG. These results were not associated with the results of DI but were significantly associated with full 24-hour analysis of QRS.
  
  
  CONCLUSIONS
  R/S variability in lead V1 between selected fragments of 24-hour ECG can be considered a predictor of potentially incomplete BIVP confirmed by further complete 24-hour ECG analysis in patients with appropriate pacing reported during DI.
authors.affiliation: Clinic of Cardiac Rehabilitation and Noninvasive Electrocardiology, the Institute of Cardiology in Warsaw, Poland.
authors.forename: Dominika
authors.initials: D
authors.lastname: Pyszno-Prokopowicz
authors.affiliation: the Clinic of Heart Rhythm Disorders, the Institute of Cardiology in Warsaw, Poland.
authors.forename: Rafał
authors.initials: R
authors.lastname: Baranowski
authors.affiliation: the Clinic of Heart Rhythm Disorders, the Institute of Cardiology in Warsaw, Poland.
authors.forename: Robert
authors.initials: R
authors.lastname: Bodalski
authors.affiliation: the Clinic of Heart Rhythm Disorders, the Institute of Cardiology in Warsaw, Poland.
authors.forename: Magdalena
authors.initials: M
authors.lastname: Madej
authors.affiliation: Clinic of Cardiac Rehabilitation and Noninvasive Electrocardiology, the Institute of Cardiology in Warsaw, Poland.
authors.forename: Ryszard
authors.initials: R
authors.lastname: Piotrowicz
mesh_terms: D000328:Adult; D000368:Aged; D058406:Cardiac Resynchronization Therapy; D015716:Electrocardiography, Ambulatory / Q000379:methods*; D005080:Exercise Test; D005260:Female; D006333:Heart Failure / Q000503:physiopathology* / Q000628:therapy*; D006801:Humans; D008297:Male; D008875:Middle Aged; D010865:Pilot Projects; D011237:Predictive Value of Tests; D016896:Treatment Outcome
keywords: 24-hour ECG; 6-minute walk test; cardiac resynchronization pacing; the QRS-variability