Abdominal Aortic Aneurysm 순환기 내과 R3 김민경/prof. 김 원

Definition Abdominal Aortic Aneurysm Aneurysm occurring in any portion of the infradiaphragmatic aorta In 1991, Aortic diameter > 1.5 times measured at the level of the renal arteries J Vasc Surg 1991;13:452-48 Normal value: 2cm (1.4-3cm) Most AAAs are infrarenal – patients often have other aneurysms, including iliac (41%) and femoropopliteal (15%) lesions

Epidemiology In USA Incidence of AAA has increased during the past twe decades and Over the last three decades, incidence has tripled 1% - 5% of general population affected 4% - 8% of the male population aged 60 years or older 1.5 million people have AAAs 15,000 deaths annually due to ruptured AAAs in the US  13th leading cause of death > 50,000 procedures per year for AAA repair 100,000 – 250,000 new cases discovered each year Prevalence increases with age 4.8% in men aged 65-69 years 10.8% in men aged 80-83 years 1.0 -2.2% in women

Etiology and Risk Factors Specific cause Trauma, infection, inflammatory disease(Behcet, Takayasu) connective tissue disorder Most AAA are non-specific  risk factor*(odds ratio, OR) Protease-TIMP-2, PAI-1, smoking(5.6), Male sex(4.6), Family history(2) Atherosclerosis, Hypertension In smokers, AAA vs Coronary artery dis. = 3:1 In smokers, AAA vs cerebrovascular dis. = 5:1 *Odds Ratios From Aneurysm Detection and Management (ADAM) Veterans Affairs Cooperative Study Group, Ann Inter Med 1997

Clinical feature No obvious symptoms of the disease  detected as an incidental If symptoms present, the risk of rupture increases Abdominal pain, Lower Back pain extended to the buttocks, groin or legs, Pulsating sensation in the abdomen Symptoms indicating a rupture may include: Sudden onset of severe back or abdominal pain Dizziness, fainting and/or sudden weakness Rupture carries a 90% mortality Approximately 40% of patients with ruptured AAAs die prior to presentation to the emergency department Only 10% to 25% of individuals with ruptured AAAs survive until hospital discharge

Abdominal Aortic Aneurysms How Big is the Problem? Natural history of AAA Although, small AAA can become enlarged with time Mean expansion rate is initially slow and then increases exponentially Finally RUPTURE or REPAIR may be occur In US, ruptured AAA : 4 to 5% of sudden deaths, 13th most common cause of death 5 year cumulative rupture rate of incidentally diagnosed AAA : 25 to 40% for > 5cm, compared with 1to 7% for 4.0 to 5.0 cm Elective repair of AAA is performed with mortality rates averaging less than 5%

Risk for rupture Annual rupture risk Rate of expansion - Ruptured VS non-ruptured: 0.82 vs 0.42cm Baseline diameter rate per year 2.8 to 3.9 cm 0.19 cm 4.0 to 4.5 cm 0.27 cm 4.6 to 8.5 cm 0.35 cm

Risk for rupture Rupture risk

Why Screen for AAA at All? The Multicentre Aneurysm Screening Study (MASS) into the effect of abdominal aortic aneurysm screening on mortality in men: a randomised controlled trial Lancet 2002; 360 65-74 aged men randomised Control group Screening group Mortality follow up AAA Not AAA Screening tool: US Prevalence of AAA : 4.9% Repair : 1) diameter ≥ 5.5cm 2) expansion rate ≥ 1cm/year 3) symptomatic AAA Mean follow up: 4 years Conclusion: significant reduceds the risk of AAA related mortality by about 50% in men  Screening for High risk population is recommended Aneurysm related death control:screen  0.86:0.49/1000personyears HR 0.58

Screening Guideline United States Prevention Services Task Force Ann Intern Med. 2005;142 Men and ages 65 to 75, who ever smoked: should be screened on time for AAA by US ACC/AHA guidelines Circulation. 2006;113(11):e463-654. Men, 60 years or older, who are either siblings or offspring with AAAs should PEx and US Men, age 65 to 75, who ever smoked

Diagnosis Physical examination: 52% sensitivity Approximately 30% of asymptomatic AAA are discovered Imaging studies Plain abdominal radiograph: “eggshell” pattern of calcification Ultrasonography: Sensitivity 100% Iinitial evaluation, screening, surveillance in size CT and MRI are better : Most precise test Size of the aortic lumen, Amount and location of mural thrombus, Calcification Choice for patients with renal insufficiency: MRI But greater cost, contrast, radiation arteriography

Treatment Medical therapy and surveillance Open repair Endovascular aneurysm repair Diameter < 5cm, the annual risk of rupture is similar to or lower than the risk of surgery UK Small Aneurysm trial 83% men, AAA diameter 4.0 to 5.5cm, asymptomatic Early elective surgery or surveillance every 6 month Repair, when > 5.5cm, expansion ≥ 1cm/year, symptomatic Initial survival disadvantage for early surgery because of a 30day operative mortality BUT the need for surgical repair of an AAA increases over time

Medical therapy and surveillance Small /intermediate size (< 5.5cm) ACC/AHA guidelines 4.0 to 5.4: US or CT every 6 to 12 month 3.0 to 4.0: US every 2 to 3 years Cessation of smoking: with AAA or Family Hx of AAA should be advised to stop smoking and offered cessation intervention Risk factor reduction : HTN, dyslipidemia for reduction of all cause mortality Beta blockers: mean expansion rate significant lower Antibiotic therapy Roxithromycin for 28days; mean annual expansion rate of the aneurysm was redued

When to intervene? Elective repair Symptom, size > 5.5cm, Rapid expansion rate, Morphologoy (saccular, fusiform with distal embolization or complication) Consider Risk Factors for Rupture Size (it really does matter), Hypertension, COPD(smoking)

Endovascular versus Open Repair of Abdominal Aortic Aneurysm The United Kingdom EVAR Trial Investigators* N Engl J Med 2010;362:1863-71. Randomised controlled trial, AAA>5.5cm, Age >60 yrs Baseline characteristics; no significant differences Operative mortality: at 30 days after surgery 1.8% in EVAR vs 4.3% in OR

Long-Term Outcome of Open or Endovascular Repair of Abdominal Aortic Aneurysm N Engl J Med 2010;362:1881-9. Six years after randomization  The cumulative overall survival rates were 69.9% for open repair and 68.9% for endovascular repair, for a difference of 1.0 percentage point

How best to treatment? Open repair or Endovascular repair Surgery Elective open repair: Average mortality 4% Re-intervention rate is lower Significant short & long-term morbidity and short term mortality mortality : 3 - 5%, morbidity : 22 - 30% High risk surgical group : comorbidity Patients > 75 years of age have a higher perioperative mortality rate Average 7 to 10 days hospitalization

Benefits of EVAR Lower short term mortality rate and similar overall mortality Overall lower morbidity Shorter hospital stay: 1 - 3 days vs. 5 - 13 days Safer option for high risk patients: most have significant concomitant disease (e.g., CAD, COPD) Minimal Anesthesia Patient comfort

Summary Men who are 65 to 75 and who ever smoked Screening for AAA at once by imaging modality Only 1% of 65 year old men who have a negative US will develops AAA innext 5 years AAA < 4cm are unlikely to rupture in the next five years Incidentally diagnosed AAA in population based sample, rupture rate of AAA withdiameter 4 to 5cm : 1-7% Screening for AAA at once by imaging modality If Abdominal aorta aneurism present Management according to guideline CT angiograph: anatomy, complication, size, ect. Indicated and if possible, consider endovascular aneurysm repair Peri- and after- procedure, Risk factor and comorbidity(DM,HTN) control