Cardiothoracic ratio as a prognostic marker in heart failure with preserved ejection fraction

The cardiothoracic ratio (CTR), derived from chest X-ray, is an established metric for quantifying cardiac size and has prognostic value in acquired heart disease. However, its association with echocardiographic parameters and clinical outcomes in heart failure with preserved ejection fraction (HFpEF) remains inadequately characterized.

This analysis was performed using the PURSUIT-HFpEF registry, a prospective multicenter observational study for HFpEF. Among 1238 patients registered, 1195 with CTR data at discharge were included. Patients were categorized into three groups: CTR <50 % (N = 199), 50-59 % (N = 631), and ≥60 % (N = 365). Associations of CTR with echocardiographic indices and clinical outcomes were evaluated.

The median CTR at discharge was 56 % (interquartile range: 51-61 %). Increased CTR was associated with impaired hemodynamics on Doppler echocardiography but not with the left ventricular (LV) end-diastolic or end-systolic volume indices. Conversely, CTR demonstrated moderate correlations with the left atrial volume index (r = 0.39), indexed right ventricular diameter (r = 0.28), inferior vena cava end-expiratory diameter (r = 0.30), and LV mass index (r = 0.18) (all p < 0.001). During a 36-month follow-up, 687 patients experienced the composite of death or rehospitalization for heart failure. Event rates increased with the CTR category (<50 %: 44.2 % vs. 50-59 %: 57.2 % vs. ≥60 %: 65.2 %; log-rank p < 0.001). Compared with CTR <50 %, CTR ≥60 % independently predicted the composite endpoint (hazard ratio, 1.47; 95 % confidence interval, 1.09-1.98; p = 0.011) after multivariable adjustment.

In patients with HFpEF, increased CTR reflected hemodynamic compromise, along with enlargement of the left atrium and right-sided chambers without LV cavity dilatation. CTR ≥60 % independently predicted adverse clinical outcomes, supporting its value for risk stratification in this population.