Myocarditis-related videos on TikTok: a cross-sectional analysis of content quality and user engagement.

Background: Public attention to myocarditis has increased markedly since the coronavirus disease 2019 (COVID-19) pandemic and vaccine-related discussions. Because misleading online content may distort symptom recognition, treatment-seeking behavior, and vaccine attitudes, the quality and clinical completeness of myocarditis-related social media information have important public health implications. This study evaluated the characteristics, clinical content coverage, user engagement, and information quality of myocarditis-related videos on TikTok. Methods: This was a cross-sectional content analysis of Chinese-language myocarditis-related TikTok videos retrieved using the keyword "myocarditis" in the mainland Chinese internet environment. Videos published before April 16, 2026 were screened for eligibility. The search was conducted using a newly registered account. Video characteristics, uploader type, user engagement metrics, and five clinical content domains, including etiology, symptoms, diagnosis, treatment, and follow-up recommendations, were extracted. Two cardiologists independently assessed video quality and reliability using the Global Quality Score (GQS) and modified DISCERN (mDISCERN). Discrepancies were adjudicated by a senior cardiovascular physician. All statistical analyses were performed using R version 4.3.3, including Mann-Whitney Results: A total of 150 videos were included. Health professionals were the most common uploaders (73%), followed by news organizations (19%) and general users (8%). Clinical content coverage was uneven: symptoms were discussed most frequently (64%), followed by etiology (35%) and diagnosis (30%), whereas follow-up recommendations (19%) and treatment (17%) were less commonly addressed. Videos posted by health professionals had significantly higher GQS and mDISCERN scores than those from non-professional sources, but non-professional videos generated greater audience engagement. Longer video duration was associated with higher GQS scores [β=0.004; 95% confidence interval (CI): 0.003-0.006; P<0.001] and mDISCERN scores (β=0.002; 95% CI: 0.001-0.004; P<0.001), whereas engagement metrics were not associated with information quality. Conclusions: Myocarditis-related videos on TikTok showed a mismatch between content credibility and popularity. Longer video duration was associated with higher information quality, but clinical content coverage remained incomplete. Future digital health communication should include more expert-led, accessible, and clinically actionable content that clearly explains key clinical information. Platform-level support, including clearer verification of medical creators and increased visibility of trustworthy health information during periods of high public concern, may help improve online health literacy and reduce the potential harms of misinformation.