Heart size on chest CT and its association with acute heart failure in the emergency department

INTRODUCTION. Acute heart failure (AHF) is a diagnosis requiring rapid treatment. Cardiomegaly on chest radiograph is a common marker of cardiac pathology used to identify AHF, but it has limited sensitivity. Low-dose chest CT (LDCT) may improve assessment, though no standardised CT method exists. We examined the association between LDCT heart-to-lung ratio and clinical AHF. METHODS. We included 230 consecutive emergency department patients with acute dyspnoea. Maximal heart and lung diameters were measured on axial LDCT slices using automated segmentation (TotalSegmentator v1). A heart-to-lung ratio (%) was calculated. AHF diagnosis was adjudicated by cardiologists. Logistic regression assessed the association between heart-to-lung ratio, analysed as a continuous variable, and AHF (OR per one-percentage-point increase with 95% CI). RESULTS. Among 230 patients, 100 were diagnosed with AHF. Using heart-to-lung ratio categorically, 106 had < 50% and 124 ≥ 50%. Using heart-to-lung ratio continuously, a one-percentage-point increase in heart-to-lung ratio was associated with AHF (OR: 1.19, 95% CI: 1.12-1.27, p < 0.001), with an optimal cut-off of 52% (area under the curve = 0.85). CONCLUSIONS. The heart-to-lung ratio on LDCT was significantly associated with AHF, with an optimal threshold just above the radiographic cut-off. Standardising CT-specific cut-offs may enhance diagnostic accuracy in emergency care.