Glossary
Definitions for the CT-derived phenotypes, ECG-derived features, and endpoint terms used across HIER Institute studies. Every term includes the exact data dictionary fields it maps to — tap a chip to open the dictionary pre-filtered to that field.
CT-derived cardiovascular phenotypes
Coronary artery calcium (CAC)
Agatston-scored calcification in the coronary arteries on non-contrast CT.
Quantifies subclinical atherosclerosis. Categorized 0 / 1–99 / 100–299 / ≥300. Predictive of MACE independent of traditional risk factors.
Epicardial adipose tissue (EAT)
Visceral fat between myocardium and visceral pericardium.
Segmented within the pericardium, thresholded −190 to −30 HU. Volume and mean attenuation predict incident coronary events, AF, and HFpEF independent of CAC.
Thoracic aortic calcium (TAC)
Calcified plaque burden in the thoracic aorta.
Agatston-analog score; adds prognostic value in older adults and radiation-exposed cohorts.
Myocardial mean HU
Average CT attenuation of the left-ventricular myocardium.
Reduced attenuation correlates with edema, fibrosis, or fatty infiltration; a candidate imaging biomarker of subclinical cardiotoxicity.
Cardiac substructure dose
Dose delivered to specific cardiac substructures rather than the whole heart.
LAD, left main, LV, LA, sinoatrial and atrioventricular nodes each have distinct radiosensitivity and downstream event profiles.
Mean heart dose (MHD)
Average dose to the whole heart across the treatment course.
Summary metric relating to lifetime coronary event risk (Darby 2013). Insufficient on its own — use with substructure DVH.
EQD2
Biologically equivalent dose at 2 Gy per fraction.
Normalizes hypofractionated regimens using α/β = 3 for late cardiac effects. Enables cross-cohort dose comparison.
ECG-derived features
Rhythm
Underlying cardiac electrical rhythm.
Sinus, atrial fibrillation, flutter, paced, or other. Baseline non-sinus rhythm excludes patients from the incident-AF at-risk denominator.
QTc
Heart-rate–corrected QT interval.
Bazett correction by default. QTc prolongation is a candidate marker of drug and radiation cardiotoxicity.
LVH criteria
ECG-based indicators of left-ventricular hypertrophy.
Sokolow–Lyon and Cornell criteria; associated with pressure overload and adverse cardiovascular outcomes.
ECG-derived age / risk score
Deep-learning estimate of biological cardiovascular age or MACE risk from a 12-lead ECG.
Foundation-model ECG embeddings capture conduction and repolarization patterns invisible to human readers and add discriminative signal to CT-only models.
Endpoint terms
MACE (composite)
Major adverse cardiovascular events — primary composite endpoint.
Time to first cardiovascular death, MI, stroke, HF hospitalization, or coronary revascularization. Non-cardiovascular death is a competing risk.
Cardiovascular death
Adjudicated cause-specific cardiovascular mortality.
Death certificate + EHR + SSDI linkage, adjudicated by two reviewers with tiebreaker per 09_adjudication.csv.
Myocardial infarction (MI)
Incident MI per Fourth Universal Definition.
Type 1 (atherothrombotic) and type 2 (supply–demand mismatch) distinguished; recurrent events tracked for count-based sensitivity.
Stroke
Imaging-confirmed ischemic or hemorrhagic stroke.
TIA excluded from primary endpoint but tracked as secondary. Requires neurology consult plus brain imaging.
HF hospitalization
Admission for acute decompensated heart failure.
Requires intravenous diuresis or inotropes plus a discharge diagnosis of HF. Subclassified HFrEF vs HFpEF when LVEF is available within 90 days.
Coronary revascularization
PCI or CABG.
Staged procedures within 30 days count as a single event for time-to-first analyses.
Incident atrial fibrillation
First documented AF or flutter ≥30 seconds.
AF-naive at-risk denominator; prior AF from problem list or historical ECG excludes patients.
CTRCD
Cancer therapy–related cardiac dysfunction.
Symptomatic HF, or asymptomatic LVEF decline ≥10 points to <53%, or ≥15% relative decline in GLS using cardio-oncology imaging definitions.
Competing risks (Fine–Gray)
Subdistribution-hazards handling of non-fatal endpoints when death is a competing event.
Reported alongside cause-specific Cox as a prespecified robustness check.
00_data_dictionary.csv.