Clinical and cardiovascular magnetic resonance profile of cardiomyopathy patients from South Africa: Pilot of the IMHOTEP study

BACKGROUND

Cardiomyopathy is an important cause of heart failure, however, there is notable lack of data on causes and manifestations of cardiomyopathy in Africa.

AIMS

The African Cardiomyopathy and Myocarditis Registry Program (IMHOTEP) aims to address the knowledge gap on etiology, treatment, and outcomes of cardiomyopathy in sub-Saharan Africa.

METHODS AND RESULTS

We conducted a single-center pilot study to delineate the clinical and cardiovascular magnetic resonance (CMR) phenotypes of cardiomyopathy in South African patients. Assessment of the first 99 adult incident cases [mean age 36.8 ± 12.5 years; females 53.5%] enrolled in IMHOTEP showed that dilated cardiomyopathy (n = 77) was commonest, followed by hypertrophic (n = 13), restrictive (n = 5) and arrhythmogenic (n = 4) cardiomyopathies. A broad range of etiologies were encountered with secondary causes identified in 42% of patients. Onset of symptoms in the peripartum period was observed in 47% of women, and peripartum cardiomyopathy was diagnosed in 32.1% of women recruited. In addition to electrocardiography and echocardiography, CMR was performed in 67 cases and contributed diagnostically in a third of cases. Acute inflammation was rarely observed [2%] on CMR, however, late gadolinium enhancement (LGE) was noted in 92% of cases.

CONCLUSION

We report a diverse spectrum of causes of cardiomyopathy in the South African population, with secondary, potentially treatable, etiologies in a significant proportion of cases. CMR was useful in delineating specific phenotypes and etiologies, influencing clinical care. A higher-than-expected burden of LGE was observed in this young patient cohort - the implications of which are yet to be determined.

Cardioprotective effects of antiretroviral treatment in adolescents with perinatal HIV infection are heterogeneous depending on age at treatment initiation

The cardioprotective effects of antiretroviral treatment (ART) in adolescents with perinatal HIV infection (APHIV) may depend on age at ART initiation. We used cardiovascular magnetic resonance (CMR) to characterize and compare residual cardiac changes in apparently healthy APHIV with early and delayed ART initiation compared to sex- and age-similar HIV uninfected peers. We defined early and delayed ART as, respectively, treatment initiated at <5 years and ≥5 years of age. Cardiac function, mechanical deformation, geometry and tissue composition were assessed. APHIV had distinct albeit subclinical cardiac phenotypes depending on timing of ART initiation. For example, changes in early ART suggested comparatively worse diastology with preserved systolic function while delayed ART was associated with comparatively increased diffuse fibrosis and LV dilatation with reduced systolic function. The long-term clinical significance of these changes remains to be determined.

Myocardial extracellular volume fraction is positively associated with activated monocyte subsets among cART-treated persons living with HIV in South Africa

BACKGROUND

Despite treatment with combination antiretroviral therapy (cART), persons living with HIV (PLWH) are at higher risk of cardiac structural abnormalities that may presage clinical heart failure, including myocardial fibrosis. This study assessed whether circulating cellular and soluble protein markers of immune activation cross-sectionally associate with myocardial fibrosis among cART-treated PLWH in South Africa.

METHODS

Participants were enrolled in Khayelitsha township near Cape Town, SA. Cardiac magnetic resonance imaging was performed. Plasma protein biomarkers were measured using enzyme-linked immunoassays and monocyte phenotypes were evaluated using flow cytometry. Associations were assessed using multivariable linear and logistic regression.

RESULTS

Among 69 cART-treated PLWH, mean (SD) age was 48 (10) years, 71% were female, and time since HIV diagnosis was 9 (6) years. Evidence of left ventricular fibrosis by late gadolinium enhancement was present in 74% of participants and mean (SD) extracellular volume fraction (ECV) was 30.9 (5.9)%. Degree of myocardial fibrosis/inflammation measured by ECV was positively associated with percentages of circulating non-classical and intermediate monocyte phenotypes reflecting inflammation and tissue injury.

CONCLUSION

These data generate hypotheses on possible immune mechanisms of HIV-associated non-ischemic myocardial disease, specifically among cART-treated PLWH in sub-Saharan Africa, where the majority of the HIV burden exists globally.

Simulating Subject-Specific Aortic Hemodynamic Effects of Valvular Lesions in Rheumatic Heart Disease

Rheumatic heart disease (RHD) is a neglected tropical disease despite the substantial global health burden. In this study, we aimed to develop a lower cost method of modeling aortic blood flow using subject-specific velocity profiles, aiding our understanding of RHD's consequences on the structure and function of the ascending aorta. Echocardiography and cardiovascular magnetic resonance (CMR) are often used for diagnosis, including valve dysfunction assessments. However, there is a need to further characterize aortic valve lesions to improve treatment options and timing for patients, while using accessible and affordable imaging strategies. Here, we simulated effects of RHD aortic valve lesions on the aorta using computational fluid dynamics (CFD). We hypothesized that inlet velocity distribution and wall shear stress (WSS) will differ between RHD and non-RHD individuals, as well as between subject-specific and standard Womersley velocity profiles. Phase-contrast CMR data from South Africa of six RHD subjects with aortic stenosis and/or regurgitation and six matched controls were used to estimate subject-specific velocity inlet profiles and the mean velocity for Womersley profiles. Our findings were twofold. First, we found WSS in subject-specific RHD was significantly higher (p < 0.05) than control subject simulations, while Womersley simulation groups did not differ. Second, evaluating spatial velocity differences (ΔSV) between simulation types revealed that simulations of RHD had significantly higher ΔSV than non-RHD (p < 0.05), these results highlight the need for implementing subject-specific input into RHD CFD, which we demonstrate how to accomplish through accessible methods.

Left ventricular remodeling and its correlates among adolescents with perinatally acquired HIV in South Africa

BACKGROUND

Left ventricular (LV) remodeling and its transitions from compensatory adaptations to LV dysfunction have not been examined in adolescents with perinatally acquired HIV infection (PHIV). We used cardiovascular magnetic resonance (CMR) in a cross-sectional study to characterize PHIV-related progressive LV remodeling in adolescents in South Africa.

METHODS

Adolescents with PHIV on antiretroviral treatment and their HIV uninfected peers completed 3 T CMR examination. We defined LV remodeling by LV mass/volume (M/V) ratio, modelling progressive LV remodeling as increasing M/V ratio. Linear regression models were applied to estimate the correlates of progressive LV remodeling.

RESULTS

Overall, 71 adolescents with PHIV [mean age: 15.2 years; 54% male] and 36 HIV uninfected [15.1 years; 42% male] peers were enrolled. Adolescents with PHIV had lower mean LV M/V ratio (0.68 vs. 0.75 g/mL; p = 0.004) than HIV uninfected peers, without LV hypertrophy in either group. Among adolescents with PHIV, increasing M/V ratio was accompanied by increasing interstitial volume [adjusted mean change (AMC) per 0.1 g/mL M/V ratio: 1.75 mL, p < 0.001] with no change in global circumferential strain (GCS) [AMC per 0.1 g/mL M/V ratio: -0.21%, p = 0.48]. However, in HIV uninfected individuals, increasing M/V ratio was accompanied by increasing peak GCS [AMC per 0.1 g/mL M/V ratio: -1.25%, p = 0.039] with no change in interstitial volume (AMC per 0.1 g/mL M/V ratio: 1.16 mL, p = 0.32].

CONCLUSIONS

Successfully treated PHIV is associated with less severe LV remodeling in adolescence when compared to HIV uninfected controls. LV remodeling in PHIV is associated with disproportionate expansion of the non-contractile interstitium not accompanied by improved GCS.

Diagnostic value of cardiovascular magnetic resonance in acute peripartum cardiomyopathy (PPCM)

Introduction

Peripartum cardiomyopathy (PPCM) is characterised by left ventricular (LV) dilatation and systolic dysfunction developing towards the end of pregnancy or in the first five months postpartum. Cardiovascular magnetic resonance (CMR) allows for comprehensive evaluation of myocardial structure, function, and tissue characteristics. There is a dearth of studies investigating utility of CMR in PPCM.

Purpose

To evaluate diagnostic benefit of multiparametric assessment of myocardial oedema, fibrotic burden, and strain impairment in PPCM using CMR.

Methods

Eighteen consenting women with newly diagnosed PPCM and 20 female, age-matched healthy controls (HCs) underwent CMR imaging on a 3T MR scanner. A comprehensive, contrast-enhanced CMR protocol was used including cines, native T1 and T2 mapping, myocardial strain analysis, and extracellular volume (ECV). Images were evaluated qualitatively and semi-quantitively for the presence of late gadolinium enhancement (LGE)

Results

Patients with PPCM (median age of 34.5 years [IQR 25–38]) presented with severely impaired LV ejection fraction (LVEF) of 31.4% (IQR 19.6–37.9) and reduced right ventricular (RV) ejection fraction (RVEF) of 37.2% (IQR 21.6–51.7). Global longitudinal strain (GLS) was significantly reduced in PPCM patients (−8.9% [IQR −10.8 to −5.6] vs. −19.7 [−21.9 to −16.3], p&lt;0.001) compared to HCs. LGE was present in 13 (81.2%) PPCM patients and included linear or circumferential mid-wall, patchy and diffuse patterns (LGE mass 19.1g [IQR 15.0–26.5] vs. 11.4g [8.8–13.2] in HCs, p&lt;0.001). Patients with PPCM had significantly higher T1 times (1369.3ms [IQR 1343.7–1409.7 vs. 1207.8ms [IQR 1194.8–1241.3], p&lt;0.001) and ECV (36.5% [32.7–37.0] vs. 27.5 [26.3–28.5], p&lt;0.001) compared to HCs. ECV, native T1 and T2 times did not differ between PPCM patients presenting with LVEF ≤35% and &gt;35%. RV dysfunction (present in 61.1% of PPCM cohort) was associated with significantly higher ECV (37.0% [IQR 36.5–38.4] vs 33.4% [IQR 28.5–37.0], p=0.05 and higher T1 (1409.0ms [IQR 1349.0–1443.0] vs. 1311.3ms [IQR 1299.3–1369.3], p=0.015) compared to those with preserved RV function. LV fibrosis was not significantly different between PPCM patients with and without RV dysfunction. LGE mass correlated negatively with LVEF and RVEF (r=−0.540, p=0.001; r=−0.568, p&lt;0.001), respectively. There was a strong positive correlation between LGE mass and native T1 (r=0.619, p&lt;0.001), LGE mass and GLS (r=0.638, p&lt;0.001) and moderate correlation with ECV (r=0.528, p=0.001) (Figure 1). Small, sub-centimetre pericardial effusions were noted in 83.3% of PPCM patients vs. 10% in HCs (p&lt;0.001).

Conclusion

For the first time, we report a high prevalence of myocardial fibrosis in well-phenotyped patients with newly diagnosed PPCM. Increased LGE mass was associated with severe impairments in LV strain, LVEF and RVEF. RV dysfunction was associated with significantly higher ECV and native T1 times.

Funding Acknowledgement

Type of funding sources: None.

Myocardial Fibrosis Among Antiretroviral Therapy-Treated Persons With Human Immunodeficiency Virus in South Africa

BACKGROUND

Heart failure is a prominent cardiovascular disease (CVD) manifestation in sub-Sarahan Africa. Myocardial fibrosis is a central feature of heart failure that we aimed to characterize among persons with human immunodeficiency virus (PWH) in South Africa.

METHODS

Cardiovascular magnetic resonance (CMR) imaging was performed among PWH with viral suppression and uninfected controls, both free of known CVD. Plasma levels of N-terminal pro B-type natriuretic peptide (NT-proBNP) were measured. Comparisons by human immunodeficiency virus (HIV) status were made using linear and logistic regression, adjusted for age, sex, and hypertension.

RESULTS

One hundred thirty-four PWH and 95 uninfected persons completed CMR imaging; age was 50 and 49 years, with 63% and 67% female, respectively. Compared with controls, PWH had greater myocardial fibrosis by extracellular volume fraction ([ECV] absolute difference, 1.2%; 95% confidence interval [CI], 0.1-2.3). In subgroup analyses, the effect of HIV status on ECV was more prominent among women. Women (vs controls) were also more likely to have elevated NT-proBNP levels (>125 pg/mL; odds ratio, 2.4; 95% CI, 1.0-6.0). Among all PWH, an elevated NT-proBNP level was associated with higher ECV (3.4% higher; 95% CI, 1.3-5.5).

CONCLUSIONS

Human immunodeficiency virus disease may contribute to myocardial fibrosis, with an effect more prominent among women. Research is needed to understand heart failure risk among PWH within sub-Saharan Africa.

Cardiovascular imaging modalities in the diagnosis and management of rheumatic heart disease

Rheumatic heart disease (RHD) is prevalent in sub-Saharan Africa, where the capacity for diagnosis and evaluation of disease severity and complications is not always optimal. While the medical history and physical examination are important in the assessment of patients suspected to have RHD, cardiovascular imaging techniques are useful for confirmation of the diagnosis. Echocardiography is the workhorse modality for initial evaluation and diagnosis of RHD. Cardiovascular magnetic resonance is complementary and may provide additive information, including tissue characteristics, where echocardiography is inadequate or non-diagnostic. There is emerging evidence on the role of computed tomography, particularly following valve replacement surgery, in the monitoring and management of RHD. This article summarises the techniques used in imaging RHD patients, considers the evidence base for their utility, discusses their limitations and recognises the clinical contexts in which indications and imaging with various modalities are expanding.

Review of cardiovascular magnetic resonance in human immunodeficiency virus-associated cardiovascular disease

Despite ongoing advances in the treatment of patients with human immunodeficiency virus (HIV) or acquired immunodeficiency syndrome (AIDS), they remain a major global public health concern conferring an increased risk of morbidity and mortality in affected individuals. This is, in part, because of the widespread dysfunction imposed by HIV and its treatment on the cardiovascular system, including the myocardium, valvular apparatus, pericardium and coronary, pulmonary and peripheral vasculature. In recent times, cardiovascular magnetic resonance (CMR) imaging has emerged as the gold standard tool for assessment of a variety of indications, allowing comprehensive characterisation of functional, morphological, metabolic and haemodynamic sequelae of several cardiovascular pathologies. Furthermore, continued advancement in imaging techniques has yielded novel insights into the underlying pathophysiology and guides future therapeutic strategies. In this article, we review the various clinical phenotypes of HIV-associated cardiovascular disease and highlight the utility of CMR in their assessment.