Beyond Ejection Fraction: Segmental Dysfunction and Outcomes in Chagas Cardiomyopathy Assessed by Cardiac Magnetic Resonance Feature Tracking - CMR-FT.

Background: Chronic Chagas Cardiomyopathy (CCC) is characterized by progressive myocardial dysfunction and ventricular aneurysms. CMR-FT has demonstrated higher sensitivity detecting early myocardial dysfunction in different types of cardiomyopathies. However, the relationship between apical–basal gradients and clinical outcomes in CCC remains unclear.

Methods: Retrospective analysis of patients with CCC referred for CMR evaluation (2016-2022). CMRs were performed on a 1.5T Philips Ingenia scanner. Global longitudinal strain (GLS) and segmental strain were extracted using a Feature-tracking strain module. To quantify the relative deformation pattern between segments, we developed the CHAMP ratio, defined as the average longitudinal strain of apical and mid segments divided by basal strain. Clinical outcomes were collected during follow-up from medical records and telephone calls.

Results: 55 patients were included (64 ± 11 years, 53% women). Controls presented significantly more negative GLS compared with all Chagas groups (p< 0.05). The highest strain ratios were found in groups without aneurysms, while the lowest ratios were seen in groups with aneurysms, despite the Ejection Fraction (EF) (Figure 1).

During follow-up (median 2,6 years), 25 patients experienced the primary combined outcome (all-cause mortality, stroke, heart failure hospitalization, and cardiac transplantation). Patients with a low strain ratio (< 1.58; cut-off ROC) showed a higher risk of the primary outcome. Univariable analysis showed a hazard ratio of 2.46 (95% CI 0.97–6.26, p=0.058). After adjustment for age, the trend remained similar (HR 2.16, 95% CI 0.82–5.67, p=0.118), suggesting increased risk. Patients classified in the low strain ratio group experienced earlier and more frequent events than those in the high ratio group (Log-rank p=0.051) (Figure 2)



Device implantation is frequently required in CCC patients; in our cohort, 27 patients (49%) experienced the outcome. In a logistic regression, patients with low strain ratio (< 1.026; cut-off ROC) had a significantly higher likelihood of device implantation (OR 3.68, 95% CI 1.07–12.7, p=0.038*). Patients with a low ratio had almost twice the risk of requiring a device implantation compared with those with high ratio (HR 1.96, 95% CI 0.91–4.20, p=0.085). This trend remained similar after adjusting for age (HR 1.92, 95% CI 0.89–4.13, p=0.094). Patients with low ratio showed a trend of higher risk with shorter event-free survival on Kaplan–Meier analysis (log-rank p=0.072) (Figure 2)

Conclusion: The CHAMP ratio identifies segmental dysfunction in CCC and provides prognostic information by stratifying the risk of adverse outcomes and device implantation. Although limited by a relatively small size, trends observed across outcomes underscore the potential clinical utility of this index. Larger and multicenter studies are needed to confirm and expand these observations.

CHAMP Ratio Across CCC Patient Subgroups and Control. CHAMP: CHagas Apex/Mid over Proximal [basal] strain ratio)
Kaplan–Meier survival curves in patients with chronic Chagas cardiomyopathy according to CHAMP ratio.