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

## TL;DR

This study identifies new electrocardiogram thresholds to help diagnose light chain amyloidosis cardiomyopathy in a Chinese population.

## Contribution

The paper introduces novel cut-off values for precordial voltage indexes to distinguish AL-CA from other LV hypertrophy causes.

## Key findings

- A voltage–mass ratio ≤1.72 has 86% PPV for AL-CA versus HCM.
- The same ratio has 75% PPV for AL-CA versus HTN-LVH.
- The voltage–mass ratio based on CSA showed the highest diagnostic accuracy.

## Abstract

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.