Right Ventricular Hypertrophy

Clinically indicated 12-lead ECGs prior to ICD implantation were acquired using a GE-Marquette system. ECG median beats were analyzed by two investigators using calipers and 2× magnification. At the time of analysis, investigators were blinded to all patient data (including cardiomyopathy etiology, CMR imaging results and electrophysiologic evaluation) except age, gender and race. ECGs were first analyzed for the presence of conduction defects and hypertrophy, according to the following pre-specified definitions:23 , 24
Left inferior (posterior) fascicular block (LPFB) does not affect the scoring system and if signs of right ventricular hypertrophy (RVH) are present then certain points in V1 and V2 cannot be counted (see Appendix).23 , 24 See the recent review for detailed explanations of the minor differences between these and the World Health Organization criteria.23
QRS-score criteria were then applied for the specific underlying conduction type present (see Appendix for complete scores and instructions). There are 32 possible total points and each point represents 3% of the LV mass. QRS scores for RBBB, LAFB, LAFB+RBBB and LVH have relatively minor differences from the no confounder QRS-score, however the LBBB score is fundamentally different because the electrical activation wavefront has to proceed through the ventricular septum before activating the LV (Figure 1).
For localization of scar by QRS-scoring, because the ECG is registered anatomically relative to the thorax, the LV walls, papillary muscles and fascicles are labeled accordingly (see Appendix). We subdivided the ECG scar locations into anteroseptal and/or anterior-superior versus inferior and/or posterolateral for comparison with the CMR-LGE locations.
By a trained observer, the QRS-scores take less than 5 minutes to complete per patient.

All echocardiograms are over-read by a Board Certified staff cardiologist at the Brigham and Women’s Hospital with COCATS Level 3 advanced training in echocardiography and/or ASE Board Certification in Comprehensive Adult Echocardiography. Over-readers are presented with the following key quantitative measurements made by technicians: LV end-diastolic dimension, wall thickness, end-diastolic volume, end-systolic volume, LVEF, LAVi, RVFAC, MR jet area-to left atrial area ratio, aortic valve peak antegrade velocity, and TR velocity. Over-readers review echocardiograms to confirm the accuracy of these measurements and to identify clinically important findings not otherwise represented by the technical measurements. Such clinically important findings include significant aortic insufficiency, mitral stenosis, pulmonary hypertension, or right ventricular enlargement. Over-readers must approve analysis for each study prior to study data being finalized for transfer to the ARIC Coordinating Center.
Following data transfer, the ARIC Coordinating Center incorporates LVEF, LV end-diastolic dimension, and LV wall thickness into a summary letter of Visit 5 test results, which is sent to participants as a courtesy. Additional clinically relevant findings identified by ERC over-readers are also reported in this letter.