Pocket-size echocardiography device effective for thoracic aortic aneurysm screening in hypertensive patients

Screening of thoracic aortic aneurysm (TAA) in asymptomatic patients with hypertension can be performed effectively using a pocket-size mobile echocardiography (PME) device, researchers at the Chinese University of Hong Kong (CUHK) have shown.

In the cross-sectional study, 1,529 Chinese hypertensive patients (mean age, 62 years; male, 53.8 percent) without TAA symptoms who attended the Prince of Wales Hospital’s hypertension clinic and family medicine clinic between June 2016 and July 2018 received point-of-care (PoC) screening of TAA (defined as a maximum aortic diameter of ≥4.5 cm or a ≥50 percent increase in diameter relative to the diameter of the adjacent normal segment) with a PME device. Aortic diameter measurements at different segments were obtained through parasternal and suprasternal views by a postdoctoral research fellow, with data validated and analyzed by an echocardiologist and physicians. [Ann Thorac Surg 2020, doi: 10.1016/j.athoracsur.2020.07.018]

Adequate visualization of the aortic root, proximal and distal ascending aorta, aortic arch, and descending aorta was achieved with the PME device in >99 percent of the patients.

“In our study population, the prevalence of TAA was high, at 7.5 percent. Aortic arch was the most frequent location of TAA [43 percent],” reported Professor Alex Lee of the Division of Cardiology, CUHK.

Patients with echocardiographic findings of an aortic diameter ≥4.5 cm (n=64) were offered gold-standard contrast CT of the thorax as a confirmatory test. Among 38 patients who underwent CT, aneurysm was confirmed in 35 patients, yielding a true-positive value of 92.1 percent and a false-positive value of 7.9 percent.

“Bland-Altman analysis between CT and echocardiographic measures of maximal aortic dimension showed good agreement between the two imaging modalities,” said Lee.

These results corroborate previous findings demonstrating reliability of PME (82 percent inter-observer agreement for image interpretation by nonexperts and expert echocardiographers), and the sensitivity (81–100 percent) and specificity (68–100 percent) of PoC PME for evaluation of cardiac anatomic structures compared with transthoracic echocardiography. Based on these findings, the European Association of Echocardiography supports the use of PME devices in screening programmes. [J Am Soc Echocardiogr 2011;24:1325-1330; Eur J Echocardiogr 2011;12:85-87; Ann Intern Med 2011;155:33-38]

“A complete PME examination of all aortic segments took only about 10 minutes per case,” reported Lee. “The examination can be performed by a doctor after completing a 30-minute tutorial plus supervised scanning of 20–30 cases.”

“In our study, male gender [odds ratio (OR), 2.120; 95 percent confidence interval (CI), 1.403 to 3.205; p<0.001] and older age [OR, 1.031; 95 percent CI, 1.014 to 1.049; p<0.002] were identified as independent factors associated with TAA,” Lee added. “These results suggest that careful evaluation of TAA should be considered in male hypertensive patients ≥65 years of age.”

“The PME device offers a highly feasible and potentially cost-effective method for PoC screening of TAA among asymptomatic hypertensive patients. We plan to expand this approach to other centres,” he continued.

“TAA is a silent and potentially lethal condition with an increasing incidence worldwide. In Hong Kong, it accounts for more than 1,400 hospital admissions and 300 deaths per year,” said Professor Martin Wong of the Jockey Club School of Public Health and Primary Care, CUHK. “Hypertension is an important risk factor present in >60 percent of patients with TAA.” [Surgery 1982;92:1103-1108]