Naschitz, J E, Rosner, I, Shaviv, N et al. · Journal of human hypertension · 2003 · DOI
Researchers tested how the hearts of people with ME/CFS respond to a simple physical challenge (tilting from lying down to sitting up). They measured heart rate and blood vessel responses using advanced mathematical analysis that detects patterns typically missed by standard methods. People with ME/CFS showed very different heart responses compared to healthy people and those with high blood pressure, suggesting their cardiovascular systems react abnormally to physical stress.
ME/CFS is characterized by cardiovascular dysautonomia (abnormal autonomic nervous system function), and this study provides objective mathematical tools that may detect these abnormalities more sensitively than conventional heart rate measurements. Validation of such biomarkers could help clinicians diagnose ME/CFS more reliably and monitor treatment response, addressing a major clinical need since ME/CFS currently lacks specific diagnostic tests.
This study does not establish that the FRAS score causes or triggers ME/CFS, only that it associates with the condition. The cross-sectional design cannot determine whether abnormal cardiovascular reactivity is a core feature of ME/CFS pathophysiology or a secondary consequence. The findings require validation in larger, independent samples before clinical use can be recommended.
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
Naschitz, J E, Rosner, I, Shaviv, N, Khorshidi, I, Sundick, S, Isseroff, H, et al. (2003). Assessment of cardiovascular reactivity by fractal and recurrence quantification analysis of heart rate and pulse transit time.. Journal of human hypertension. https://doi.org/10.1038/sj.jhh.1001517
BibTeX
@article{mecfsatlas-naschitz-2003-assessment-cardiovascular,
author = {Naschitz, J E and Rosner, I and Shaviv, N and Khorshidi, I and Sundick, S and Isseroff, H and Fields, M and Priselac, R M and Yeshurun, D and Sabo, E},
title = {Assessment of cardiovascular reactivity by fractal and recurrence quantification analysis of heart rate and pulse transit time.},
journal = {Journal of human hypertension},
year = {2003},
doi = {10.1038/sj.jhh.1001517},
note = {PubMed: 12574789},
url = {https://www.mecfsatlas.com/evidence/naschitz-2003-assessment-cardiovascular},
}Atlas snapshot reference
ME/CFS Atlas. Generator v1 / Scanner v1.4 / policy v0.1. Accessed 2026-05-30. https://www.mecfsatlas.com/evidence/naschitz-2003-assessment-cardiovascular
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