Although an increased pulmonary trunk (PT) diameter to ascending aorta (AA) diameter ratio (PT/AA ratio) is associated with pulmonary hypertension, the prognostic utility of this metric remains unexamined. We investigated whether an increase in the PT/AA ratio, as measured using coronary computed tomographic angiography, is associated with the risk of all-cause death. We identified 1,326 consecutive patients (mean age 61 ± 13 years; 60% men) without known coronary artery disease who underwent coronary computed tomographic angiography. Patients with a history of congenital or valvular heart disease or aortic enlargement (≥4 cm) were excluded. The PT and AA diameters were measured at the PT bifurcation level. The patients were categorized by PT/AA deciles, with the ≥90th percentile (PT/AA ratio 0.9) considered elevated. All-cause death associated with a PT/AA ratio <0.9 versus ≥0.9 was evaluated using multivariate Cox proportional hazard models. During 2.9 ± 1.0 years of follow-up, 58 patients died. Patients with a PT/AA ratio ≥0.9 experienced 2.5-fold greater annualized mortality compared to those with <0.9 (3.1% vs 1.3%, p = 0.004). Adjusting for age, gender, heart rate, dyslipidemia, smoking, and coronary artery disease extent, the patients with a PT/AA ratio ≥0.9 experienced a greater mortality risk compared to patients with PT/AA ratio <0.9 (hazard ratio 3.2, 95% confidence interval 1.6 to 6.6, p = 0.001). In the 1,059 patients with left ventricular ejection fraction measurements, a lower left ventricular ejection fraction was observed in the PT/AA ratio ≥0.9 group (p <0.05). In conclusion, incrementally and independent of the traditional coronary artery disease risk factors, an elevated PT/AA ratio was associated with increased mortality risk in patients without known coronary artery disease undergoing coronary computed tomographic angiography.
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