Novel Cut-Off Values of Precordial Voltage Indexes for Light Chain Amyloidosis Cardiomyopathy in a Chinese Population

Low QRS voltage relative to left ventricle (LV) thickness is one of the red flag characteristics in the diagnosis of cardiac amyloidosis, and it can be measured by specific indexes. Few studies have clearly defined the diagnostic threshold of voltage indexes for light chain amyloidosis cardiomyopathy (AL-CA) patients and other patients with LV hypertrophy. This case-control study analyzed electrocardiograms and echocardiograms of patients with AL-CA, hypertrophic cardiomyopathy (HCM), and hypertension left ventricular hypertrophy (HTN-LVH) seen at a single university center from 2008 to 2022. Low QRS voltage and three different precordial voltage indexes were evaluated. Diagnostic thresholds for rule-in and rule-out were calculated for AL-CA against each control group. A single voltage-mass ratio based on cross-sectional area (CSA) exhibited most accurate diagnostic accuracy, and the value of ≤1.72 aids the rule-in of AL-CA against other causes of left ventricular hypertrophy, providing a positive predictive value (PPV) of 86% versus HCM and 75% versus HTN-LVH.