Association of sympathetic denervation, myocardial hypoperfusion, and fibrosis with ventricular arrhythmias in chronic Chagas cardiomyopathy

Background: Chronic Chagas cardiomyopathy (CCC) manifests as heart failure, thromboembolic events, and sudden cardiac death (SCD). Although SCD may be the presenting event, there is still no recommendation for early cardioverter/ defibrillator implantation in current guidelines. Objective: To evaluate the correlation between autonomic denervation, myocardial hypoperfusion, fibrosis, and ventricular arrhythmias in patients in the early stages of CCC. Methods: Cross-sectional study of 29 patients with CCC and preserved left ventricular function who underwent SPECT with iodine-123-meta-iodobenzylguanidine (¹²³I-mIBG), myocardial perfusion SPECT with technetium-99m sestamibi (^99mTc-MIBI), and cardiac magnetic resonance (CMR) with gadolinium, divided into two groups according to on 24h Holter findings: arrhythmia (> 6 ventricular premature complexes/hour and/or nonsustained ventricular tachycardia; n = 15) or no-arrhythmia (< 6 ventricular premature complexes/hour and no ventricular tachycardia; n = 14). Results: Significant correlations were observed between parameters of the three cardiovascular imaging modalities and the presence of ventricular arrhythmia. Denervation on mIBG correlated moderately with diffuse fibrosis, represented by ECV on CMR (r = 0.55, P = 0.002). Hypoperfusion by MIBI-SPECT correlated with fibrosis by both LGE (r = 0.66, P = 0.005) and extracelluar volume (ECV) (r = 0.56, P = 0.002). We also observed a moderate correlation between the extent of myocardial areas with denervation and hypoperfusion (r = 0.48, P = 0.007). Conclusion: The presence of autonomic denervation, myocardial hypoperfusion, and fibrosis was associated with ventricular arrhythmia in the early stages of CCC. A combination of these parameters can improve stratification of SCD risk in these patients. (author)