Power Pitch 5: Apical Regional Dysfunction Assessment using CMR - Feature Tracking by Magnetic Resonance Imaging in Patients with Chronic Chagas Cardiomyopathy

: Chronic Chagas Cardiomyopathy (CCC) is a severe complication related to a parasitic infection (Chagas’ Disease). Ventricular aneurysms are described in around 60% of the patients with CCC and are associated with more severe ventricular dysfunction and a higher risk of embolism. CMR - CMR-Feature tracking (CMR-FT) has been used to detect myocardial dysfunction with a higher sensitivity in the early stages of different cardiomyopathies, even when other variables are preserved. However, the role of CMR-FT in CCC remains unclear.

Methods:

We conducted a retrospective analysis of adult patients with CCC referred to CMR evaluation between 2016 and 2022. CMRs were performed on a 1.5T Philips Ingenia scanner. Ventricular volumes and function values were obtained from SSFP cine images and CMR-FT values from SAX LAX (2CH, 4CH, and LVOT) SSFP cine images were processed using certified software. Global and segmental (basal-mid-apical) values were obtained and compared to previously published CMR-FT normal values. Four groups with CCC were analyzed: 1 - Left Ventricular Ejection Fraction (LVEF) > 40% with no aneurysm, 2 - LVEF < 40% with no aneurysm, 3 - LVEF > 40% with aneurysm, and 4 - LVEF < 40% with an aneurysm. Descriptive statistics, ANOVA test, T-test, and logistic regression analysis were applied. A p-value of less than 0.05 was considered statistically significant.

Results: 55 patients with CCC having completed a clinically indicated CMR were enrolled (mean age 64 ±11years; 53% women). Thirty-five cases had an LVEF of >40% and ten patients with apical aneurysms. Mean Global Radial Strain (GRS), Global Circumferential Strain (GCS) and Global Longitudinal Strain (GLS) values were 19.8±9.3, -12.78±4.6 and -11.13±4.2, respectively and were all significantly different when compared the healthy reference values (p-values= < 0.001). Within the four categories of CCC, GLS values were significantly different and were progressively worse across the spectrum of the disease (p-values= < 0.001) (Fig. 1). Groups 1 and 2 demonstrated an abnormal mean apical strain despite the absence of a visible apical aneurysm (Fig. 2) suggesting subclinical segmental dysfunction.  When normalizing the mean apical and mid strain values to the basal segments, the highest strain ratios were found in groups without aneurysms while the lowest ratios were seen in groups with aneurysms, independent of the LVEF (Fig. 3), highlighting a progressive distal LV cavity dysfunction across the various stages of CCC.

Conclusion:

In patients with CCC, regional myocardial strain in CCC as assessed by CMR-FT has the potential to detect subclinical apical dysfunction and uncover early stages of apical aneurysm development.