title: Right ventricular failure predicted from right bundle branch block: cardiac magnetic resonance imaging validation.
abstract: BACKGROUND
  Right ventricular (RV) failure has proven to be independently associated with adverse outcomes. Electrocardiographic parameters assessing RV function are largely unknown, making echocardiography the first line for RV function assessment. It is however, limited by geometrical assumptions and is inferior to cardiac magnetic resonance imaging (CMRI) which is widely regarded as the most accurate tool for assessing RV function.
  
  
  METHODS
  We seek to determine the correlation of ECG parameters of right bundle branch block (RBBB) with RV ejection fraction (EF) and RV dimensions using the CMRI. QRS duration, R amplitude and R' duration were obtained from precordial lead V1; S duration and amplitude were obtained from lead I and AVL. RV systolic dysfunction was defined as RV EF <40%. RV systolic dysfunction group (mean EF of 24±10%) were compared with normal RV systolic function group which acted as control (mean EF of 48±8%). CMRI and ECG parameters were compared between the two groups. Rank correlations and scatter diagrams between individual CMRI parameters and ECG parameters were done using medcalc for windows, version 12.5. Sensitivity, specificity and area under the curve (AUC) were calculated.
  
  
  RESULTS
  RV systolic dysfunction group was found to have larger RV end systolic volumes (90±42vs.59±40 mL, P=0.02). ECG evaluation of RV dysfunction group revealed longer R' duration (103±22vs.84±18 msec, P=0.005) as compared to the control group. The specificity of R' duration >100 msec to detect RV systolic dysfunction was found to be 93%. R' duration was found to have an inverse correlation with RV EF (r=-0.49, P=0.007).
  
  
  CONCLUSIONS
  Larger RV end systolic volumes seen with RV dysfunction can affect the latter part of right bundle branch leading to prolonged R' duration. We here found prolonged R' duration in lead V1 to have a highly specific inverse correlation to RV systolic function. ECG can be used as an inexpensive tool for RV function assessment and should be used alongside echocardiography to evaluate RV dysfunction when CMRI is not available.
authors.affiliation: Department of Cardiology, Methodist Hospital, Brooklyn, NY, USA.
authors.forename: Santhosh R
authors.initials: SR
authors.lastname: Devarapally
authors.affiliation: University of North Carolina at Chapel Hill, NC, USA.
authors.forename: Sameer
authors.initials: S
authors.lastname: Arora
authors.affiliation: Department of Cardiology, Methodist Hospital, Brooklyn, NY, USA.
authors.forename: Ali
authors.initials: A
authors.lastname: Ahmad
authors.affiliation: Department of Cardiology, Methodist Hospital, Brooklyn, NY, USA.
authors.forename: Mike
authors.initials: M
authors.lastname: Sood
authors.affiliation: Department of Cardiology, Methodist Hospital, Brooklyn, NY, USA.
authors.forename: Amaar
authors.initials: A
authors.lastname: El Sergany
authors.affiliation: Department of Cardiology, Methodist Hospital, Brooklyn, NY, USA.
authors.forename: Terrence
authors.initials: T
authors.lastname: Sacchi
authors.affiliation: Department of Cardiology, Methodist Hospital, Brooklyn, NY, USA.
authors.forename: Barry
authors.initials: B
authors.lastname: Saul
authors.affiliation: Department of Cardiology, Methodist Hospital, Brooklyn, NY, USA.
authors.forename: Rahul
authors.initials: R
authors.lastname: Gaglani
authors.affiliation: Department of Cardiology, Methodist Hospital, Brooklyn, NY, USA.
authors.forename: John
authors.initials: J
authors.lastname: Heitner
keywords: Right bundle branch block (RBBB); cardiac magnetic resonance imaging; heart failure; right ventricular (RV) failure