Introduction:
Left bundle branch block (LBBB) with QRS duration > 120 msec is typically associated with increased ECG voltage without a necessary increase in left ventricular wall thickness. Studies assessing voltage criteria in amyloidosis and other cardiomyopathies have excluded patients with LBBB. We sought to assess the effects of QRS duration and LBBB on voltage criteria in cardiac amyloidosis.
Methods:
We performed a retrospective analysis of patients with newly diagnosed cardiac amyloidosis at our institution from 2001-2014. Low voltage in the precordial leads was defined by the Sokolow criteria (S wave in V1 plus R wave in V5 or V6 ≤ 15mm). Limb lead voltage was calculated by the sum of the entire QRS complex voltage of leads I, II and III with low voltage being defined as each lead ≤ 5 mm. Patients with left bundle branch block were propensity matched to assess voltage criteria based upon age, sex, history of HTN, amyloid type (AL vs TTR), anteroseptal thickness and BSA to those with QRS < 120msec.
Results:
In 299 subjects (age 69.6 +/- 11.7 years, male 69%, HTN 53%, AL 53%, IVS 18.1 +/- 4.1 mm, BSA 1.95 +/- 0.26, EF 48 +/- 14%), mean QRS duration was 107 +/- 25 msec with 71 patients (24%) having a QRS duration greater than 120 msec (17 LBBB). The average limb voltage was 15.1 +/- 7.3 mm with low limb lead voltage seen in 62% of patients. Low precordial lead voltage was found in 73% of patients with a mean Sokolow voltage of 12.9 +/- 7.5 mm. After propensity matching the 17 patients with LBBB on a 1:3 basis with patients with a narrow complex QRS, there was no difference in any measure of voltage criteria.
Conclusion:
LBBB is not associated with higher voltage and does not hinder the ability to detect low voltage in patients with cardiac amyloidosis.
Left ventricular electromechanical delay in patients with heart failure and normal QRS duration and in patients with right and left bundle branch block