Summary
Several international guidelines, including those in France, recommend the screening of abdominal aorta aneurysm (AAA) by ultrasound in high-risk populations. However, this preventive screening strategy is poorly implemented. Many patients who undergo transthoracic echocardiography (TTE) are at risk of AAA as defined by the guidelines, and the cardiac ultrasound machines and probes fit perfectly for AAA screening. In this literature review, we collected data from more than 20,000 patients who underwent screening for AAA during TTE, from 10 single-centre series. While the studies differed regarding patient selection and AAA definition, the feasibility of AAA screening during TTE was excellent (mostly > 90%), with the need for an average of 2–7 minutes to be added to the cardiac imaging time. The prevalence of AAA > 30 mm ranged from 0.8% to 6.5%, and up to 19% in men aged > 70 years. The risk factors for the presence of AAA among attendees of echocardiography laboratories were similar to those reported in the general population: age, male gender, smoking, hypertension, family history of AAA and prevalent atherosclerotic diseases. Some echocardiography-specific factors, such as left ventricular hypertrophy or dilation and poor left ventricular ejection fraction were also reported. To better assess the benefit of and indications for AAA screening during TTE in clinical practice, we propose a multicentre, nationwide, screening study in echocardiography laboratories in our country.
Résumé
Plusieurs recommandations dont celles en France proposent le dépistage ultrasonore de l’anévrisme de l’aorte abdominale (AAA) dans les populations à risque. Cependant ce dépistage est faiblement réalisé. D’autre part, les patients bénéficiant d’une échocardiographie transthoracique (ETT) sont pour beaucoup à risque d’AAA tels que définis dans les recommandations et les sondes et échographes utilisés pour l’ETT sont parfaitement adaptés pour l’imagerie de l’aorte abdominale. Dans cette revue de littérature, nous avons colligé les données de dix séries monocentriques de dépistage d’AAA lors d’une ETT auprès de plus de 20,000 sujets. Bien que ces séries diffèrent quelque peu en termes de recrutement et de critères de définition d’anévrisme, elles rapportent globalement une très bonne faisabilité (en majorité > 90 %), avec une durée moyenne d’examen de deux et sept minutes. La prévalence d’AAA supérieure à 3 cm varie de 0,8 % à 6,5 % selon les séries, montant jusqu’à 19 % chez les hommes supérieurs à 70 ans. Les facteurs de risque d’AAA rapportés sont ceux généralement observés en population générale: l’âge, le sexe masculin, les antécédents de tabagisme, d’hypertension ou de maladies athéromateuses, ainsi que des antécédents familiaux d’AAA. D’autres facteurs spécifiques à l’ETT ont été rapportés: une hypertrophie ou une dilatation ventriculaire gauche et une fraction d’éjection basse. Afin de mieux connaître l’intérêt et les indications d’un dépistage ciblé d’AAA durant l’ETT, nous proposons une étude multicentrique nationale de dépistage d’AAA au sein des laboratoires d’échocardiographie et des cabinets médicaux.
Introduction
Ruptured abdominal aorta aneurysm (AAA) is a major, life-threatening condition with a grim prognosis: 70% of patients die before reaching the surgery ward and another 10–15% die during the perioperative period. Hence the rates of survival at hospital discharge do not exceed 15–20% . In the USA, it is estimated that 9000 people die each year from a ruptured AAA , which corresponds to approximately 12,000 cases in Europe. However, this severe condition is preceded by a long period of silent growth of the aneurysm, which may last for more than 10 years before the occurrence of clinical signs. This is therefore a strong rationale for screening AAA for prompt prophylactic intervention, with much lower mortality and morbidity. In several countries, published guidelines advocate such screening in subjects at high risk of AAA . Owing to its availability, harmlessness and relatively low cost, ultrasound is proposed in all these guidelines as the first-line method for detecting an AAA, usually defined by an aortic diameter > 30 mm .
Notably, the majority of people with a small AAA (< 50 mm) do not die from this lesion but from other cardiovascular and general conditions. Several risk factors (smoking, hypertension, etc.) are common to AAAs and other cardiovascular diseases . Hence, patients managed by cardiologists for any cardiovascular disease should be considered at higher risk for AAA. By using ultrasound routinely to perform transthoracic echocardiography (TTE), cardiologists could take this opportunity to use the same ultrasound probe to screen systematically their patients for an AAA.
In this literature review, we collected all of the available data on the feasibility and results of AAA screening, and the risk factors for prevalent AAA in patients undergoing TTE. Finally, we propose a multicentre, epidemiological study to assess the prevalence of and risk factors for AAA in patients who benefit from TTE.
Literature data collection
In the PubMed database, we used the terms ‘abdominal aneurysm aorta’, ‘echography’ and ‘cardiac’ or ‘echocardiography’, with date restrictions from 1980 to 2009. We retrieved 220 titles, from which 20 abstracts were retained. Ultimately, we found 11 papers dealing with our topic , one of which was a case report and was excluded. Overall, we found 10 series of patients who had TTE and benefited from concomitant AAA screening.
Literature review
Regarding the feasibility of abdominal aorta visualization, although no abdominal preparation was considered before TTE, diagnostic quality image yields of 82% to 96% were reported ( Table 1 ). Eight of 10 studies reported the duration of the aorta imaging, mostly below 5 minutes. Only one study reported an average aorta imaging duration of 7.7 minutes (ranging from 1.1 to 20 minutes). Importantly, in that study, the full length of the abdominal aorta was analysed , while the AAA is located mostly at the infra-renal segment.
| First author, year [study reference] | Aorta imaging success rate (%) | Reported imaging duration |
|---|---|---|
| Eisenberg et al., 1995 | 82 | ≤ 5 minutes |
| Schwartz et al., 1996 | 86 | NA |
| Spittell et al., 1997 | 96 | Average 7.7 minutes (1–20) |
| Jaussi et al., 1999 | > 95 | ≤ 5 minutes |
| Bernard et al., 2002 | 87 | 1–5 minutes |
| Giaconi et al., 2003 | 91 | < 2 minutes |
| Bekkers et al., 2005 | 93 | NA |
| Ruggiero et al., 2006 | 95 | 33.8 ± 18.6 seconds |
| Roshanali et al., 2007 | 91 | Average 2.2 minutes (1.1–4.4) |
The details of each series, along with the prevalence rates of AAA, are summarized in Table 2 . The prevalence of AAA varied substantially from one series to another, ranging from 0.8% in a very large series of more than 14,000 patients to 6.0% in an unselected series of 250 patients , and even 6.5% in a series of patients with hypertension . Several reasons may explain these differences: first, while AAA was usually defined by a diameter > 30 mm, some authors proposed alternate definitions, with a diameter threshold set at 25, 35 or 40 mm, with a priori lower rates for those who used larger diameters. Some authors focused their screening on the infra-renal part of the aorta, while others studied the whole abdominal aorta, or even (surprisingly) disregarded the distal aorta . Notably, only two series reported data on the verification of the lesions found during TTE. Bekkers et al. reported a good correlation between diameters measured in a couple of large AAAs (> 50 mm) by computed tomography scan and ultrasound . In the study by Seelig et al., a high specificity of 9% was reported for the detection of AAA > 30 mm . All series are consistent with higher rates in the elderly and in men, whereas the participants mean age and sex ratio varied from one study to another. When study participants were preselected (e.g. according to the presence of hypertension ), higher rates of AAA were noted. Similarly, in some series, those with known AAA were excluded logically , but this was not the case in all series, and often this information was not clearly stated. Finally, unknown cases of AAA may be less frequent in tertiary care units ; this issue was raised by the authors of the largest series from the Mayo Clinic , who reported the lowest rates of AAA: actually patients referred to them were mostly managed already by other centres, with a higher probability to have their AAA discovered prior to the referral. This is a source of selection bias, which may be relevant to other echocardiography laboratories, depending on its healthcare network.
| First author, year [study reference] | N | Selection | Age (years) | AAA definition | Aorta segment | Prevalence (men/women) | Comments |
|---|---|---|---|---|---|---|---|
| Eisenberg et al., 1995 | 323 | Unselected | 57 | > 25 mm | Distal aorta not always visualized | 2.0% (8.5/2.5) | |
| Schwartz et al., 1996 | 250 | Unselected | – | > 30 mm | ? | 6.0% | |
| Spittell et al., 1997 | 209 | Age > 50 years with HTN | 71.3 | > 30 mm | Abdominal aorta | 6.5% (8.4/4.3) | |
| Jaussi et al., 1999 | 297 | Unselected | 58.6 | > 30 mm | Infra-renal | 5.7% (8.2/1.7) | |
| Seelig et al., 2000 | 14,876 | Unselected, age > 50 years | 68.5 | > 30 mm | Not stated | 0.8% (1.3/0.2) | Seven false positive cases (93.5% specificity) |
| Bernard et al., 2002 | 1106 | Unselected | 61 | > 35 mm | Infra-renal | 1.0% | |
| Giaconi et al., 2003 | 181 | Unselected (?) men | 61 | ≥ 30 mm | ? | 3.8% (3.8/−) | |
| Bekkers et al., 2005 | 742 | Unselected | 60.5 | > 30 mm | Infra-renal | 5.7% | 81% unknown cases. Prevalence up to 19% in men aged > 70 years. Ten patients with AAA > 5 cm; five underwent abdominal CT scan: diameters correlated well ( r 2 = 0.9). |
| Ruggiero et al., 2006 | 1107 | Selected and unselected | – | – | ? | 5.6% | Only those with history of surgery for AAA excluded |
| Roshanali et al., 2007 | 1285 | Unselected | 40.7 | > 40 mm | Supra-renal only | 3.8% (4.5/3.6) | > 3 cm, 4.9%; > 5 cm, 0.5% |
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