Thermographic abnormalities associate with electrocardiogram/echocardiographic changes and mortality in systemic sclerosis: a retrospective cohort study

Objectives Cardiac involvement is common in SSc and is associated with high mortality, yet is challenging to detect. Our aim was to investigate relationships between cardiac involvement, as assessed by ECG and transthoracic echocardiography (TTE), and thermographic abnormalities.

Methods A retrospective (2015–2023) study of SSc patients attending a UK referral centre. Relevant patient characteristic/demographic data were collected. Logistic regression models were used to evaluate the association between thermographic impairment and ECG/TTE abnormalities. Thermography data were categorized by the presence/absence of ‘cold fingers’ at baseline [defined as one or more distal digits being >1°C colder than the dorsum—a distal–dorsal difference (DDD)]; and impairment with rewarming: ‘mild’, ‘moderate’, ‘severe’. Kaplan–Meier analysis described differences in survival based on thermographic abnormalities.

Results We included 266 patients (84% female, mean age 57 years). Cardiac abnormalities (≥1) were identified in approximately one-third by ECG (39%) and TTE (34%). Baseline DDDs were observed in 83% and severe thermographic impairment of rewarming in 58% of patients. Baseline DDDs were associated with ECG [odds ratio (OR) 1.18, P = 0.047] and TTE (OR 1.19, P = 0.008) in univariable analysis, with stronger associations in multivariable analysis for ECG (OR 2.36, P = 0.073) and TTE (OR 9.08, P = 0.05). Cox Proportional Hazard regression analysis revealed higher mortality risk in patients with baseline DDD [hazard ratio (HR) 6.04], male sex (HR 2.86), older age (HR 1.06) and cardiovascular comorbidities (HR 3.73). Baseline DDD was associated with significantly shorter survival (χ2d 4.04, P = 0.047).

Conclusions Thermographic abnormalities were associated with cardiac abnormalities and increased mortality in SSc patients.