New parameter for QRS complex low voltage in chagasic cardiomyopathy: the ADOC index

Low QRS complex voltage is an important predictor of death in Chagas disease. However, the parameters applied to the low-voltage classification were described by the Minnesota Code and not specifically for Chagas disease. This study aimed to analyze low QRS voltage by determining the ADOC index and averages in the frontal and horizontal electrocardiographic planes, establishing possible clinical implications.

A cross-sectional study of patients with Chagas disease was performed using the Mann-Whitney U test and Spearman's correlation. The amplitudes of each QRS were analyzed, and the sum of the DII and V5 derivations of the ADOC index and the arithmetic means of the QRS complexes in the frontal and horizontal planes were determined.

The ADOC index was correlated with the highest risk of stroke and death according to the Rassi score. The ADOC index (p=0.046) and mean mQRS were inversely proportional to the Rassi risk of death score (p=0.038). The ADOC index proved to be more sensitive (75.0%) and accurate (67.4%) in identifying patients at elevated death risk using the Rassi score. Finally, a positive correlation was observed between the QRSFm and QRSHm indicators and ADOC index (r=0.590 and r=0.857, respectively).

The ADOC index and mean of the QRS complexes are possible tools correlated with the Rassi score and risk of stroke in patients with Chagas disease.