First-line diagnostic tests to intercept primary heart involvement in systemic sclerosis: Clinical associations from the SPRING-SIR registry

Introduction: Primary heart involvement (pHI) is an overlooked and poorly characterised complication of systemic sclerosis (SSc), associated with the risk of heart failure, arrhythmia and death. Despite consensus definition by the World Scleroderma Foundation/Heart Failure Association (WSF/HFA), diagnostic criteria and risk factors remain poorly elucidated. Methods: Out of 1922 patients in the Italian national SPRING registry, we excluded those with potentially confounding conditions according to WSF/HFA, and those with incomplete ECG or echocardiographic assessment, resulting in 600 subjects with clearly defined parameters to intercept SSc-pHI. Cross-sectional and longitudinal analyses were performed to identify factors associated with pHI. Results: ECG and/or echocardiographic signs of SSc-pHI were identified in 25% of patients at enrollment and were associated with older age (OR 1.04; 95% CI 1.02-1.06), diffuse cutaneous SSc (OR 1.85; 95% CI 1.05-3.26) and intestinal symptoms (OR 1.79; 95% CI 1.03-3.08). Diastolic dysfunction (62%) and conduction disturbances (34%) were the most frequent phenotypes, while diffuse hypokinesia with reduced ejection fraction was the least common (3%). During follow-up, new-onset signs of pHI were observed in an additional 25% of patients, particularly in those with skeletal muscle involvement (HR 2.83; 95% CI 1.01-7.73). Conclusions: pHI is a severe complication potentially affecting one-quarter of patients with SSc. Early detection is crucial, particularly in those with diffuse skin fibrosis, muscular involvement and intestinal manifestations