Baroreflex Sensitivity and its Association with Arrhythmic Events in Chagas Disease

Background

Sudden death is the leading cause of death in Chagas disease (CD), even inpatients with preserved ejection fraction (EF), suggesting thatdestabilizing factors of the arrhythmogenic substrate (autonomic modulation)contribute to its occurrence.

Objective

To determine baroreflex sensitivity (BRS) in patients with undetermined CD(GI), arrhythmogenic CD with nonsustained ventricular tachycardia (NSVT)(GII) and CD with spontaneous sustained ventricular tachycardia (STV)(GIII), to evaluate its association with the occurrence and complexity ofarrhythmias.

Method

Forty-two patients with CD underwent ECG and continuous and noninvasive BPmonitoring (TASK force monitor). The following were determined: BRS(phenylephrine method); heart rate variability (HRV) on 24-h Holter; and EF(echocardiogram).

Results

GIII had lower BRS (6.09 ms/mm Hg) as compared to GII (11.84) and GI (15.23).The difference was significant between GI and GIII (p = 0.01). CorrelatingBRS with the density of ventricular extrasystoles (VE), low VE density(<10/h) was associated with preserved BRS. Only 59% of the patients withhigh VE density (> 10/h) had preserved BRS (p = 0.003). Patients withdepressed BRS had higher VE density (p = 0.01), regardless of the EF. TheBRS was the only variable related to the occurrence of SVT (p = 0.028).

Conclusion

The BRS is preserved in undetermined CD. The BRS impairment increases asdisease progresses, being more severe in patients with more complexventricular arrhythmias. The degree of autonomic dysfunction did notcorrelate with EF, but with the density and complexity of ventriculararrhythmias.