An aneurysm is defined as an increase in the size of an artery by >50% of the normal arterial diameter. According to the affected segment of the aorta, aneurysmal diseases are divided into thoracic, thoracoabdominal and abdominal aortic aneurysms (AAAs). Worldwide, the prevalence of AAAs may be as high as 8%, depending on the criteria used for diagnosis (1).

Since the introduction of endovascular repair of aortic aneurysms by Parodi et al in 1991 (2), this technique has resulted in lower short-term mortality and shorter hospital stays than open repair. Although endovascular and open repair of AAAs result in similar long-term survival overall, endovascular repair has been shown to increase the long-term survival of younger patients (3). In patients randomized to open or endovascular AAA repair, all-cause perioperative mortality and AAA-related mortality at short- and intermediate-term follow-up was lower in patients who underwent endovascular repair (4).

Due to the attractive outcomes of endovascular repair of aortic aneurysms, the overall use of the endovascular procedure has risen sharply in the last decade. Epidemiology of aortic aneurysm repair in the United States showed that endovascular aneurysm repair (EVAR) increased from 5.2 to 74% of the total number of AAA repairs from 2000 to 2010, even though the total number of AAAs remained stable at 45,000 cases per year (5). There was a 72% decline in open repair during the study period. The national trends were similar for the use of open and endovascular repair for thoracic aortic pathologies between 2000 and 2010; the rate of open repair decreased from 2.5 to 2.2 per 100,000 beneficiaries, and the rate of endovascular repair of thoracic aortic aneurysms increased markedly from 0 to 0.8 per 100,000 beneficiaries (6).

There has been little analysis of these national trends in Asian countries. Therefore, the present study aimed to evaluate the national trends for the treatment of aneurysms in Korea.

There is a global trend of increasing prevalence of endovascular repair for the treatment of aortic aneurysms. A recent epidemiological study in the US reported that the overall prevalence of endovascular aortic aneurysm repair has risen sharply from 5.2% in 2000 to 74% in 2010 (8). In a German study, the rate of treatment by EVAR increased from 24.0 to 40.3% in males and from 17.3 to 31.0% in females between 2006 and 2009 (9). In the present study, the rate of endovascular repair of aortic aneurysms increased 16.17-fold during the study period.

Population-adjusted frequencies of aneurysm repair differ from country to country. According to an epidemiological study in the US, the number of AAA repairs conducted was 14.22 per 100,000 (5). However, in the present study, the total number of aneurysm repairs conducted per 1,000,000 Medicare Beneficiaries was 39 in 2004 and 70 in 2013. Aneurysm repair is performed 2.0–3.6 times more frequently in the US than in Korea.

Several hypotheses have been suggested for the lower rate of aneurysmal repair in Korea. Firstly, the overall incidence of aortic aneurysms is lower in Korea than in Western countries. Ultrasound screening and autopsy series have indicated that the prevalence of AAAs (≥3 cm) is 3–10% for patients aged >50 years old in Western countries (10). In a Veterans Affairs screening study of >73,000 patients aged 50–79 years old, the prevalence of AAAs ≥3 cm was 4.6% (11). In the Asian population, the reported prevalence of AAAs varies. Spark et al (12) suggested that the prevalence of AAAs in the Asian population was lower than that in the Caucasian population. Although a screening study of the general population in Korea demonstrated that the prevalence of AAAs was 4.5% in a high-risk group (13), another screening study during echocardiograms indicated that 0.2% of the study population was newly diagnosed with AAAs (14).

A second explanation for the lower rate of aneurysmal repair in Korea is that there is no nationwide screening program for AAAs. In the US, the Centers for Medicare and Medicaid Services provide free ultrasound screening for AAAs to certain beneficiaries for whom AAA screening may be advantageous, including people who have a family history of AAAs, and men aged 65–75 years old who have smoked ≥100 cigarettes in their lifetime (15). Thirdly, the deployment of medical resources for vascular surgeries in Korea may be different than in Western countries. The Department of Health in the Korean government has focused on the treatment of patients with cancer. The budget for health has been allocated to screen for and treat cancer more so than vascular disease. The deployment of medical resources in Korea may be further evaluated by the health policy authorities.

Despite an overall downward trend in prevalence, the frequency of open repair of aortic aneurysms increased during the study period (1.22-fold). The increased rate of open repair of aortic aneurysms may be associated with the increasing frequency of open repair of ascending aortic aneurysms (RR 1.38, 95% CI: 1.25–1.54), AAAs (RR 1.39, 95% CI: 1.21–1.59, P<0.0001), and aortic arch aneurysms (RR 1.65, 95% CI: 1.40–1.94).

The number of open repairs for descending thoracic aortic aneurysms and isolated iliac artery aneurysms decreased from 299 to 208 (RR 0.86, 95% CI: 0.72–1.04) and from 43 to 31 (RR 0.68, 95% CI: 0.43–1.09) between 2004 and 2013, respectively. This may be associated with the dramatic increase in endovascular repairs of these aneurysms. Endovascular repair of descending thoracic aortic aneurysms is less invasive than open repair and may result in a lower mortality rate, as evidenced by single-center studies or industry-sponsored registries (16,17). Although population-based data from England showed that operative mortality for degenerative descending thoracic aneurysms was similar after either thoracic endovascular aortic/aneurysm repair or open repair (18), endovascular repair is predominantly used for descending thoracic aortic aneurysms.

The iliac branch device (IBD) technique has been introduced as an appealing and effective solution to avoid complications during the repair of aortoiliac aneurysms with extensive iliac involvement, or of isolated iliac artery aneurysms. Perlani et al (19) reported that the estimated patency rate of the internal iliac branch was 91.4% at 5 years, and the rate of freedom from any re-intervention was 90% at 1 year and 81.4% at 5 years. Oderich et al (20) suggested the use of the novel surgeon-modified hypogastric branch stent graft to preserve pelvic perfusion in the circumstance that a commercial IBD is unavailable. Furthermore, Fatima et al (21) published various methods of pelvic revascularization in patients with aortoiliac aneurysms involving one or both common iliac arteries, such as flared iliac stent grafting, the sandwich technique, external-to-internal iliac arterial stenting, double bifurcated stent grafting, or novel hybrid revascularization. In Korea, there are no commercially available IBDs. Therefore, pelvic revascularization is achieved with the surgeon-modified IBD or the novel endovascular or hybrid procedures suggested by Fatima et al (21).

The present study revealed that the endovascular repair of AAAs overtook open repair as the most commonly utilized technique between 2010 and 2011. These results are consistent with a previous epidemiologic study in the US that reported that endovascular repair overtook the open repair of AAAs between 2005 and 2006 (5). This 5-year gap may be related to the late adoption of endovascular treatment for aortic aneurysms and the administrative policies in Korea.

Several limitations of the present study should be acknowledged. As the present study is a retrospective analysis based on an administrative database, there is an intrinsic limit to the number of variables that can be measured. Follow-up data and long-term outcomes were unavailable. In addition, further evaluation is required after more detailed data are collected, such as the number of ruptured and unruptured aortic aneurysms, the prevalence of co-morbidities, the duration of hospital stays, and the rates of mortality according to treatment modality.

In conclusion, a total of 32,130 patients underwent aneurysm repair between 2004 and 2013. The frequency of open repair increased 1.2-fold with an overall downward trend. The prevalence of endovascular repair markedly increased 15.3-fold. Although the frequency of open repair of aortic aneurysms increased at the level of the ascending aorta, aortic arch, and abdominal aorta, the frequency of this technique decreased for descending thoracic aortic aneurysms and isolated iliac artery aneurysms. In Korea, the endovascular repair of AAAs overtook open repair as the most commonly utilized technique between 2010 and 2011.