Heart fibrosis may contribute to sudden death in systemic sclerosis

Lung, kidney fibrosis common too, suggesting need for 'multimodal treatment by Andrea Lobo, PhD | May 20, 2025

Most people with systemic sclerosis (SSc) have fibrosis, or scarring, that affects the heart muscle, a study in Australia shows.

In two-thirds of the cases, heart fibrosis had no other, or secondary, cause, helping to explain mortality and sudden cardiac death in these patients, according to the researchers. Lung and kidney fibrosis were also common in SSc.

Also, combinations of fibrosis, inflammation, and/or vascular disease in the heart, lungs, and kidneys were identified in 30% to 45% of SSc cases, “suggesting that multimodal treatment may be needed to prevent organ damage and improve outcomes in SSc,” the scientists wrote. The study, “Pathological contributors to organ damage and mortality in systemic sclerosis: a nationwide matched case-control study,” was published in Seminars in Arthritis and Rheumatism.
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SSc is an autoimmune disease marked by inflammation and fibrosis in the skin that may also occur in the internal organs, particularly the heart, lungs, and kidneys. In fact, internal organ involvement is a strong predictor of mortality with the condition, the scientists said, particularly due to cardiopulmonary and kidney disease.

​High rate of heart fibrosis
Researchers in Australia analyzed autopsy reports from 59 people with SSc and 59 without SSc, who died from sudden death — natural and unexpected death within an hour after the onset of symptoms or 24 hours after being last seen alive and well — or sudden cardiac death, meaning sudden death of primary cardiac cause. Causes of death in the SSc group included cardiac, pulmonary and kidney complications. Both the SSc patients and the controls had a similar median age at the time of death (64 vs. 62), and were predominantly women and white.

Myocardial (heart muscle) fibrosis was overall 10.7 times more common among SSc patients (82% vs. 31%) and more likely extensive (72% vs. 27%), than in the controls. Also, myocardial inflammation (24%) and abnormalities in the small blood vessels that supply the heart (18%) were only seen with SSc.

People with SSc more frequently had enlarged hearts (60% vs. 26%), increased thickening of the heart muscle (41% vs. 3%) and the right ventricle wall (35% vs. 8%), and issues with the mitral valve, which separates the heart left chambers (32% vs. 11%) and the pericardium, which is the sac that surrounds and protects the heart (29% vs. 7%).

Myocardial fibrosis was attributed to SSc in two-thirds of the patients, as they didn’t have coronary artery disease or a secondary cause.

“These findings highlight the challenge of developing more sensitive diagnostics for the identification of [changes in the myocardium that disrupt the heart rhythm], a critical step for risk stratification and sudden cardiac death prevention,” the researchers wrote.

Similarly, lung fibrosis was 23 times more common among people with SSc (55% vs. 5%). Lung inflammation (30%) and blood vessel abnormalities suggestive of pulmonary hypertension (46%) were found in patients, but not in the controls.

People with SSc were about three times more likely to have scarring or other forms of kidney damage (59% vs. 35%) and inflammation (19% vs. 7%). Blood vessel thickening was more than six times more frequent in the SSc group (54% vs. 16%).

Among SSc cases, a combination of at least two of fibrosis, inflammation, or blood vessel disease, was seen simultaneously in 31% of hearts, 41% of lungs, and 45% of kidneys.

In addition, complications affecting other organ systems were seen in the gastrointestinal tract of SSc patients (39%) and controls (18%). Abnormalities in the tube that connects the throat with the stomach, or esophagus, were in SSc cases only and included fibrosis (74%), inflammation (35%), and blood vessel issues (26%).
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“This suggests that concurrent pathologies are implicated in the development of organ damage, perhaps explaining why no single treatment modality is universally effective for SSc manifestations,” the researchers wrote. “Combination therapy for SSc may be an effective approach.”