Miwa, Kunihisa, Fujita, Masatoshi · Internal medicine (Tokyo, Japan) · 2009 · DOI
This study found that many ME/CFS patients experience heart-related symptoms like shortness of breath, chest pain, fainting, and dizziness. Using heart imaging tests, researchers discovered that about one-third of ME/CFS patients had smaller-than-normal hearts that pump less blood than expected, which may contribute to their fatigue and other symptoms.
This study is important because it provides objective cardiac evidence for ME/CFS patients, validating that cardiovascular dysfunction is real and measurable in this population. Understanding the structural basis of heart abnormalities may help explain exertional symptoms and guide more targeted treatment approaches for cardiac-related aspects of ME/CFS.
This study does not prove that small heart size causes ME/CFS or that cardiac dysfunction is the primary driver of fatigue in all patients. It is a cross-sectional snapshot and cannot establish whether cardiac changes develop before, during, or after ME/CFS onset. The small sample size and lack of severity stratification limit generalizability to all ME/CFS populations.
About the PEM badge: “PEM required” means post-exertional malaise was an explicit required diagnostic criterion for participant inclusion in this study — not that PEM was studied, observed, or discussed. Studies using criteria that do not require PEM (e.g. Fukuda, Oxford) are tagged “PEM not required”. How the atlas works →
The first block is for the primary paper and is the citation you should use in research work. The atlas-snapshot line only applies if you are specifically referring to this atlas’s reading of the paper on the date shown.
Primary citation
Miwa, Kunihisa & Fujita, Masatoshi (2009). Cardiovascular dysfunction with low cardiac output due to a small heart in patients with chronic fatigue syndrome.. Internal medicine (Tokyo, Japan). https://doi.org/10.2169/internalmedicine.48.2347
BibTeX
@article{mecfsatlas-miwa-2009-cardiovascular-dysfunction,
author = {Miwa, Kunihisa and Fujita, Masatoshi},
title = {Cardiovascular dysfunction with low cardiac output due to a small heart in patients with chronic fatigue syndrome.},
journal = {Internal medicine (Tokyo, Japan)},
year = {2009},
doi = {10.2169/internalmedicine.48.2347},
note = {PubMed: 19881233},
url = {https://www.mecfsatlas.com/evidence/miwa-2009-cardiovascular-dysfunction},
}Atlas snapshot reference
ME/CFS Atlas. Generator v1 / Scanner v1.4 / policy v0.1. Accessed 2026-05-28. https://www.mecfsatlas.com/evidence/miwa-2009-cardiovascular-dysfunction
Contribute
Private, reviewed by a human. Not a public comment thread.