Are there more acute cardiac hospitalizations in winter in patients with systemic sclerosis? An analysis from the National Inpatient Sample

Objective: Cold-induced transient myocardial ischemia has been described in patients with systemic sclerosis. The clinical impact of cold exposure in systemic sclerosis patients with acute cardiac conditions is unknown. We compared the seasonal variation of acute cardiac hospitalizations in patients with and without systemic sclerosis. Methods: We performed a retrospective cross-sectional study using the National Inpatient Sample from 2016 to 2019. The primary outcome was acute cardiac hospitalization primarily due to heart failure, acute myocardial infarction, or cardiac arrhythmias. We compared the proportion of acute cardiac hospitalizations in each season in patients with and without systemic sclerosis. We also performed a subgroup analysis by US geographic region (Northeast, Midwest, South, West). Results: There were a total of 10,118,002 acute cardiac hospitalizations over the 4-year study period. Compared to those without systemic sclerosis, patients with systemic sclerosis who were hospitalized for acute cardiac care were younger (mean age 67 +/- 13 vs 70 +/- 14 years, p < 0.01), a greater proportion were female (82% vs 45%, p < 0.01), and a smaller proportion were Caucasian (68% vs 71%, p < 0.01). There was a lesser proportion of traditional cardiovascular risk factors in systemic sclerosis compared to non-systemic sclerosis patients. There was no significant difference in the proportion of winter admissions between systemic sclerosis and non-systemic sclerosis patients for total acute cardiac hospitalizations (26.4% vs 25.9%, p = 0.51), heart failure (27.0% vs 26.5%, p = 0.64), acute myocardial infarction (26.9% vs 25.5%, p = 0.50), or arrhythmias (24.3% vs 25.0%, p = 0.68). The results were consistent across all four US geographic regions. Conclusion: Our study did not support that patients with systemic sclerosis had a disproportionally higher risk of acute cardiac hospitalization in winter compared to the general population. We found that systemic sclerosis patients hospitalized for acute cardiac care had a lower burden of traditional cardiovascular risk factors than their non-systemic sclerosis counterparts.