Mortality risk as a function of the ratio of pulmonary trunk to ascending aorta diameter in patients with suspected coronary artery disease

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.