Medical management of abdominal aortic aneurysms

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1 Medical management of abdominal aortic aneurysms

2 Definition of AAA - Generally a 50% increase in native vessel diameter - Diameter 3 cm - Relative measures compared with nondiseased aortic segments less useful in diffuse arteriomegaly or generalized aortic enlargement - An absolute diameter 3.5 cm

3 Incidence I - Prevalences of unsuspected, asymptomatic AAA : Men > 60 yrs : 4-8% Women > 60 yrs : % - A national AAA screening programme for men aged 65 in England. -> In Leicester, since 1993 : Caucasians 865/18431 (4.69%) Asian 2/446 (0.45%) Afro-Caribbean 4/102 (3.9%) M.K. Salem et al. Eur J Vasc Endovasc Surg 2009

4 Mortality of AAA - Ruptured AAA and complication after surgical treatment are responsible for > 15,000 deaths/yr in the US. - Mortality of ruptured AAA > 90% - Emergent operation of ruptured AAA : 30-60% mortality - Elective operation for asymptomatic AAA : 2-6% mortality

5 Risk factors for AAA I -Advanced age -Male -Smoking : 7 times more likely to develop in a smoker than a nonsmoker : duration >> rather than total amount of cigarettes smoked. - Family history : 12% to 19% of those undergoing aneurysm repair having a first-degree relative with an AAA.

6 Risk factors for AAA - II - Treated and untreated hypertension - High cholesterol levels - Coronary artery disease (CAD) - Intermittent claudication - Caucasian than Asian, Black race - Inversely related with diabetes mellitus - Greater height - Atherosclerosis

7 Risk factors for aneurysm progression UK small aneurysm trial : 1743 patients were monitored for changes in AAA diameter by ultrasonography over a mean follow-up of 1.9 years. : Mean initial AAA diameter, 43 mm (range 28 to 85 mm) Mean growth rate, 2.6 mm/yr (95% range,1.0 to 6.1 mm/yr) : Baseline diameter growth accelerates as the aneurysm enlarges. : higher for current smokers (faster expansion, by 0.4mm/yr)

8 Screening for AAA For men age 65 to 75 years, an invitation to attend AAA screening reduces AAA-related mortality.

9 Recommendations for aneurysm screening and surveillance (SVS practice guideline,2009) One-time ultrasound screening for AAA -for all men at or older than age 65, -as early as age 55 for those with a family history of AAA. - women at or older than age 65, who have smoked or have a family history.

10 Decision to treat (SVS practice guideline,2009) - Repair is recommended for patients that present with an AAA and abdominal or back pain - Elective repair is recommended for patients that present with a fusiform AAA 5.5 cm in maximum diameter, in the absence of significant co-morbidities. - Elective repair should be considered for patients that present with a saccular aneurysm. - Surveillance is recommended for most patients with a fusiform AAA in the range of 4.0 cm to 5.4 cm in maximum diameter. - Young, healthy patients, and especially women, with AAA between 5.0 cm and 5.4 cm may benefit from early repair.

11 Medical management during the period of AAA surveillance

12 Tobacco - a specific risk factor for AAA disease prevalence, incidence, and progression - Nearly all AAA patients (90%) relate a history of smoking - Several small studies have associated continued cigarette smoking with more rapid aneurysm expansion. - When the studies are considered together, continued smoking is associated with a 15% increase in growth rate that has important implications when compounded over several years. - Smoking cessation!!

13 Statin -Statinreduces the progression of atherosclerosis and improves clinical outcomes in cardiovascular diseases. - Also demonstrate additional biological effects (ie, pleiotropic effects), including reduction of C-reactive protein levels, that may be relevant to the pathogenesis of AAA disease.

14 At the present time, No sufficient evidence to recommend statin therapy to be initiated for the diagnosis of AAA alone

15 β-blockers In several animal studies, propranolol might have beneficial effects on aneurysmal disease Due to its hemodynamic properties and its biochemical effects on matrix proteins. -> 2 multicenter randomized trials A trial reported by Lindholt et al. : Propranolol did not inhibit aneurysm expansion. - low compliance in the propranolol arm (only 22% of patients continued the medication for 2 years) - Mean growth rate was slightly higher in propranolol group

16 ACEi and ARB - I - Hackam et al. analyzed ruptured (n=3379) and nonruptured (n=11,947) aortic aneurysms from 1992 to ACE inhibitor use within the prior 3 to 12 months was less frequent among those admitted for aneurysm rupture (OR 0.82, CI 0.74 to 0.90).

17 ACEi and ARB - II - Patients who discontinued ACE inhibitors within the past 3 to 12 months, there was a harmful effect in favor of aneurysm rupture (OR 1.39, CI ). -The case-control study by Schouten et al and UK aneurysm trial data did not find a relationship between ACE inhibitors and aneurysm expansion rates.

18 Macrolides - Chlamydia pneumoniae has been found in atherosclerotic plaque and the wall of AAAs. - A small study by Lindholt et al. suggested that serological evidence of a C. pneumoniae infection was associated with an increased rate of aneurysm expansion.

19 Tetracyclines -Petrinicet al. elastase-induced rat model. : doxycycline could suppress aortic wall MMP activity, elastin degradation, and aneurysm development

20 Smoking cessation is recommended to reduce the risk of AAA growth and rupture. Level of recommendation: Strong/Quality of evidence: High Screening for AAA is recommended for first degree relatives of patients presenting with an AAA. Level of recommendation: Strong/Quality of evidence: High Conclusion The use of beta blockers to reduce the risk of AAA expansion and rupture is not recommended. Level of recommendation: Strong/Quality of evidence: Moderate Statins may be considered to reduce the risk of AAA growth. Level of recommendation: Weak/Quality of evidence: Low Doxycycline, roxithromycin, ACE inhibitors, and ARBs are of uncertain benefit in reducing the risk of AAA expansion and rupture. Level of recommendation: Weak/Quality of evidence: Low