Myocardial involvement in SSc can present with focal hypo- or akinesia, ranging to various degrees of global left ventricular (LV) systolic dysfunction and dilatation. Myocarditis and fibrotic replacement are responsible for segmental and/or global ventricular abnormalities in the acute and chronic phases, respectively. Right ventricular (RV) hypertrophy, dilatation and dysfunction—often associated with anomalous movement of the interventricular septum—suggest the presence of PAH. These findings, particularly when they are nuanced, can be misdiagnosed by echocardiography, whereas they are more easily to detect with CMR. Specific cardiac structures, such as the right ventricle, LV apex and atrial chambers, may be challenging to approach with ultrasound. CMR overcomes the limitations of the transthoracic echocardiography, by combining different cine images, even also in not canonical cut planes, providing a more comprehensive evaluation. Recently, five distinct CMR phenotypes of cardiac SSc have been described, based on the presence of dysfunction and/or dilatation of one or both ventricular chambers: dilated right heart with RV failure, biventricular dilatation and dysfunction, normal function with large cavity sizes, normal function with normal cavity, normal function with small cavity, the latter two subsets being associated with a more favourable outcome (9). Several studies evaluated the potential correlation between morpho-functional parameters and clinical outcomes, often with conflicting results (10). Among these parameters, RV ejection fraction has been shown to independently predict all-cause mortality (9). SSc patients frequently develop signs and symptoms of heart failure (HF), regardless of systolic function. According to the results from the European Scleroderma Trials and Research (EUSTAR) registry, 36.2% of SSc patients with cardiac involvement meets diagnostic criteria for HF with preserved ejection fraction (HFpEF), while HF with reduced (HFrEF) or mildly reduced ejection fraction (HFmrEF) has been reported much less frequently, each accounting for 1.5% of cases (11). Indeed, LV systolic dysfunction has been reported in about 5.4% of cases; however, MI and fibrosis can alter biventricular myocardial relaxation and compliance, leading to elevated pulmonary venous pressures, thereby increasing RV afterload. This results in RV hypertrophy and subsequent diastolic dysfunction (DD), characterized by reduced RV filling time and prolonged isovolumic relaxation time, the latter indicating impaired active myocardial relaxation (12). As RV DD progresses, maladaptive remodeling with chamber dilatation develops, ultimately leading to RV systolic dysfunction. This, in turn, adversely affects left-sided chambers, further compromising LV filling. DD is closely associated with HFpEF, and numerous studies have evaluated it non-invasively using echocardiography. Tennøe et al. reported that 17% of 275 consecutive SSc patients had DD at baseline, with the prevalence increasing to 29% after a 3.4-year follow-up. Patients with DD were older and had higher rates of systemic hypertension, ischemic heart disease, atrial fibrillation, and pulmonary hypertension compared to those without DD. The presence of DD was associated with poorer survival (13). Accordingly, diastole should systematically be evaluated, being often the only functional detectable abnormality. While echocardiography remains the traditional approach for its non-invasive assessment, several applications of CMR imaging have demonstrated potential utility in the evaluation of both LV and RV diastolic function, including cine imaging for ventricular filling dynamics, phase-contrast sequences for transvalvular flow analysis, feature tracking for diastolic strain rates, and T1 mapping to detect myocardial fibrosis and impaired compliance, although the evidences remain limited (14–16).

MI, resulting from aberrant activation of the immune system, is common in SSc, although it is often clinically silent. Overt clinical myocarditis is rare, whereas recent CMR studies have highlighted the critical role of subclinical inflammation in the pathogenesis of cardiac damage. Since 2009, the definition of the Lake Louis criteria has provided the foundation for non-invasive diagnosis of myocarditis (i.e., MI), based on the identification of three diagnostic criteria: edema, hyperemia, and necrosis. These criteria are derived from T2-weighted, early gadolinium enhancement, and late gadolinium enhancement (LGE) CMR images, respectively: for the diagnosis of myocarditis, at least two of the three criteria must be present (17, 18). The advent of CMR mapping imaging has advanced tissue characterization, improving sensitivity and specificity through direct measurement of T1 and T2 relaxation times. As a result, the Lake Louis diagnostic criteria have been revised in 2018 (19). Accordingly, both myocardial edema (described as regional or global increase of native T2 or T2 signal intensity) and non-ischaemic myocardial injury (i.e., regional or global increase of native T1 or extracellular volume (EVC), or presence of LGE) must be present. The coexistence of pericardial involvement and/or LV systolic—global or regional—dysfunction further support the diagnosis.

Traditional echocardiographic parameters are often ineffective for detecting subclinical systolic impairment. However, reduced LV and RV global longitudinal strain (GLS) is common among patients with SSc and has been associated with an increased risk of all-causes mortality and hospitalization (35–37). A basal–apical gradient has also been observed, with basal segments being more affected than the apex in both ventricles (35, 38). More recently, feature-tracking CMR analysis has emerged as a novel method for studying biventricular deformation and, accordingly, myocardial performance. Several studies have evaluated LV deformation in SSc using future-tracking analysis, showing that LV and RV strains are often impaired despite preserved LV ejection fraction (39, 40). Gotschy et al. reported the potential prognostic utility of deformation analysis, demonstrating that reduced GLS and elevated T1 can identify subjects at increased risk of death for any cause (18). Faher et al. demonstrated that GLS assessed by feature-tracking predicts overall survival regardless of cardiac output, reduced LVEF, and LGE (41). Moreover, some studies have reported significant improvement in LV and RV strain after the initiation of specific therapies for PAH, suggesting the potential utility of strain imaging for monitoring the response to therapies (42). However, data are still scarce, and further evidence is warranted.

PAH is common in SSc, with an estimated prevalence of 7–12% (43). Compared to idiopathic one, prognosis in PAH related to SSc is worse. One potential explanation seems to be a more impaired RV pump function, likely due to intrinsic abnormal collagen deposition. Additionally, microvascular disease and resulting chronic ischaemic damage have been postulated as contributing factors (44). Although CMR cannot directly measure pulmonary pressures, it provides valuable information on RV wall thickness, volumes and function, complementing echocardiographic assessment. Furthermore, assessment of fibrosis, measurement of myocardial strain and precise quantification of pulmonary and tricuspid regurgitant volumes are other potential applications. Patients with SSc-associated PAH have higher native myocardial, T2 and ECV, compared with patients without, and have more frequently pericardial effusion (9). Insertional myocardial scar, detected by LGE or native T1 elevation, is indicative of RV pressure overload, and correlates with disease severity (45). More recently, Knight et coll. Demonstrated that native T1 and indexed RV end-systolic volume are independent predictors of all-cause mortality in SSc-associated PAH, providing also potential thresholds to identify patients with a poorer prognosis (46). Given the growing body of evidence, CMR has become an integral part for comprehensive risk assessment in PAH together with the traditional prognostic predictors, offering the advantage of being non-invasive and reproducible over time.

The pericardium is frequently affected, with involvement ranging from 33 to 72% (47). Asymptomatic mild pericardial effusion is the most common finding, whereas clinically symptomatic pericardial disease is less frequent. Some patients may present with typical acute pericarditis, characterized by elevated serum inflammatory biomarkers, chest pain and pericardial rubs. Constrictive pericarditis and pericardial tamponade, although possible, occur infrequently. CMR is typically considered a second-line imaging modality for diagnosing acute pericarditis; however, its high resolution and ability to perform tissue characterization make CMR the gold standard for non-invasive evaluation. A thickened pericardium of ≥ 3 mm can be seen in both acute and chronic pericarditis. Cine imaging offers a comprehensive functional assessment of the cardiac chambers and pericardial space, revealing pericardial effusion and its potential effects on cardiac functions, such as right chambers collapse in cardiac tamponade, or septal bounce in constrictive pericarditis at real-time cine images.

Heart valves are also affected by the immune dysregulation of SSc. Nodular thickening of the tricuspid, aortic and especially mitral valves (in approximately 38% in autoptic studies), along with retraction of the chordae tendineae and consequent valvular regurgitation, are the most common valvular alteration observed (48, 49). Also anecdotical cases of non-bacterial thrombotic endocarditis have been reported (50). Due to its superior temporal resolution and widespread availability, echocardiography remains the first approach for evaluating heart valves. However, CMR, using phase contrast imaging, can be a valuable alternative for approaching valvular disorders, especially in cases with poor acoustic windows, or when results are inconclusive, providing a more precise quantification of valvular regurgitation.

Myocardial damage in SSc is also caused by repeated chronic ischaemic injury, resulting from structural microvascular impairment and abnormal vasoreactivity, rather than epicardial coronary arteries disease. Advances in myocardial perfusion imaging have spurred growing interest in the evaluation of microvascular dysfunction in SSc. The first demonstration of cold-induced coronary vasospasm in SSc was documented in several nuclear medicine studies, who found reversible myocardial perfusion defects after cold exposure, that seem to predict cardiac events and mortality in SSc (51–53). More recently, even CMR has found application in this context. Inducible subendocardial perfusion defects have been reported in about 79% of the patients assessed by stress CMR with adenosine, and resulted to be associated with higher plasmatic levels of ultrasensitive C reactive protein, suggesting a potential link between chronic MI and microvascular dysfunction (30). Gyllenhammar et al. demonstrated that patients with SSc exhibit decreased myocardial perfusion during adenosine stress, but not at rest, compared to healthy controls (54). Furthermore, Galea et coll. Reported a reduced vasodilatory response to the cold pressure test in SSc patients without cardiac symptoms, indicating a potential early role of endothelial microvascular dysfunction in the pathogenesis of cardiac damage (55). However, evidences regarding the potential prognostic implications of microvascular impairment remain limited and warrants further investigation.