Table 2.

Cardiovascular risk in spaceflight, cardiovascular risk in spaceflight and epidemiological evidence for radiation-induced cardiovascular risk

Level of evidence	Source/Model	Key cardiovascular observations	Role in risk assessment
Epidemiologic	Human: LSS (atomic bomb) and radiotherapy	Dose-dependent increase in ischemic heart disease and stroke (>0.5 Gy).	Establishes the primary terrestrial baseline for human risk.
Clinical	Human: ISS and Apollo Crews	Carotid-intima thickness shifts; microvascular remodeling in LEO.	Validates human physiological response in the space environment.
Mechanistic	Animal: simGCRsim Murine models	Accelerated atherosclerosis; myocardial fibrosis; reduced EF%.	Recapitulates the deep space (High-LET) hazard profile.
Molecular	Experimental: Omics and in vitro	RNA dysregulation; cytokine signaling; oxidative stress.	Identifies predictive biomarkers and early-warning signatures.
Epidemiological evidence for radiation-induced cardiovascular risk
Cohort type	Key examples	Exposure characteristics	Relevance to spaceflight
Atomic bomb survivors	Life Span Study (LSS)	Acute, high-dose-rate; mixed photon-neutron field.	Foundational for stochastic risk and dose–response modeling.
Clinical radiotherapy	Breast cancer and Hodgkin lymphoma survivors	High-dose, localized fractions; primarily photons.	Identifies specific tissue reactions (valvular disease, pericarditis).
Occupational	INWORKS, Mayak workers, Chornobyl liquidators	Chronic, low-dose-rate; protracted over years; primarily gamma/neutron.	Most relevant for modeling the cardiovascular effects of protracted GCR exposure.

This table summarizes the hierarchy of evidence characterizing the cardiovascular hazards associated with space travel and epidemiological evidence for radiation-induced cardiovascular risk, both categorized by research scale and clinical relevance.