An enlarged heart on a screening chest X-ray: only 52.7% of 452 had a real abnormality
In short
Among 452 asymptomatic adults whose routine health-check chest X-ray showed a cardiothoracic ratio (CTR) of 0.5 or above and who had echocardiography within six months, 238 (52.7%) had a structural cardiac abnormality. In multivariable analysis only three predictors remained independent: age 65 or older, hypertension, and ECG-detected left ventricular hypertrophy. A systolic murmur was significant on univariate analysis but did not survive adjustment.
The cardiothoracic ratio is the width of the heart divided by the width of the chest on a plain chest X-ray, and a value of 0.5 or above is usually flagged as suspected cardiomegaly. It is a line that turns up often on screening reports, and what it actually means in someone with no symptoms has rarely been quantified. This retrospective cross-sectional study at Siriraj Hospital in Bangkok looked at 452 asymptomatic adults screened between 2022 and 2025 with a CTR at or above 0.5 who went on to echocardiography within six months. Anyone with previously known structural heart disease was excluded.
Half real, half not
Structural abnormalities were found on echocardiography in 238 people, 52.7%. Turned around: nearly half of those whose heart looked enlarged on X-ray had no structural abnormality on echo. Cardiomegaly on a single film is not a diagnosis — it behaves like a screening signal with roughly even odds.
What raised the odds
- Age 65 or older — remained an independent predictor after adjustment.
- Hypertension — likewise an independent predictor.
- ECG-detected left ventricular hypertrophy — the third independent predictor.
- Systolic murmur — significant on univariate analysis, but not independent once adjusted.
The authors' conclusion is that clinical assessment and the ECG have to be read alongside the film to decide who gets referred for echocardiography — a triage rule that matters most where echo access is limited.
How a trained person should read this
Start with what the study did not cover. The population was asymptomatic general adults, and heavily trained people were not analysed separately. A heart enlarged by endurance or strength training and a heart enlarged by disease are different phenomena down to the molecular switches, so the 52.7% does not transfer to lifters as-is. What does transfer is that one of the three predictors is under your control. Age and the ECG finding are not modifiable; blood pressure is. Exercise lowered blood pressure regardless of modality, with circuit training reaching up to 13.5 mmHg. As for the ECG finding itself, the evidence points toward weaker predictive power than its reputation suggests.
This is a single-centre cross-sectional study that included only people who went on to have echocardiography, which can introduce selection bias. If a screening report flags cardiomegaly, the number to act on is a clinical assessment, not the figure in this article.
Frequently asked questions
Does cardiomegaly on a screening chest X-ray mean something is wrong with the heart?
Not necessarily. Among 452 asymptomatic adults with a cardiothoracic ratio of 0.5 or above on chest X-ray, 52.7% had a structural abnormality on echocardiography. Close to half had none.
What is the cardiothoracic ratio?
It is the horizontal width of the heart divided by the horizontal width of the chest on a plain chest X-ray. This study used 0.5 or above as the threshold for suspected cardiomegaly.
Which findings made a real abnormality more likely?
Three remained independent predictors after multivariable adjustment: age 65 or older, hypertension, and ECG-detected left ventricular hypertrophy. A systolic murmur on examination was significant only on univariate analysis.
Does a heart enlarged by training fall under this?
The study looked at asymptomatic general adults and did not analyse heavily trained people separately. Training-induced and disease-induced enlargement are explained by different mechanisms, so these proportions cannot be applied directly to athletes.
What can someone actually act on after such a finding?
Of the three predictors, blood pressure is the modifiable one. Age and the ECG finding cannot be changed, while blood pressure responds to exercise and lifestyle. The finding itself still needs a clinician to interpret.
Source: PubMed