Usefulness of an Abnormal Ankle-Brachial Index to Predict the Presence of Coronary Artery Disease

Transcription

1 Usefulness of an Abnormal Ankle-Brachial Index to Predict the Presence of Coronary Artery Disease Sittiluck Wongwantanee, MD, Damras Tresukosol, MD, and Kamol Udol MD Division of Cardiology, Faculty of Medicine Siriraj Hospital, Mahidol University Abstract Background: Ankle brachial index (ABI) is a ratio of ankle and brachial systolic blood pressure measurements and is used to interpret atherosclerotic disease of the peripheral artery system. Previous studies have shown that patients with symptomatic or asymptomatic peripheral arterial disease who have coronary atherosclerosis are at an increased risk for adverse cardiovascular events. The aim of this study was to correlate the relationship between the extent of coronary artery disease and peripheral artery disease by using coronary angiograms and ABI measurements concurrently. Methods and results: Form January 2005 to December 2005, a total of 326 patients who were suspected of having coronary artery disease underwent coronary angiography. Baseline characteristics for cardiovascular risk factors were collected. An abnormal ABI was highly specific for the diagnosis of severe coronary artery disease (77%) but had a very low sensitivity (22%). The sensitivity was higher if other coronary risk factors were combined (diabetes mellitus 25%, age>65yr 27%). In contrast complete total occlusion and a proximal left anterior descending artery (LAD) lesion did not show any correlation. A peripheral angiogram was performed in 33 patients (51 limbs, 51%) of 67 patients with an abnormal ABI. There was significant peripheral arterial stenosis in 80% of patients (27 patients, 37limbs) and 78 % of limbs (29 limbs) had involvement of the ilio-femoral artery. Conclusion: An abnormal ABI correlates with the degree of coronary artery disease. ABI has a high specificity for the diagnosis of a severe form of coronary disease (77%) but very low sensitivity (22%). Because of the high rate of iliofemoral involvement and high specificity in detecting the severe form of coronary artery disease (LM and triple vessel disease), ABI can be considered a useful test prior to a coronary angiogram which would benefit both the interventionist as well as preparation of patients and relatives. However, the low sensitivity and cost of the test limits its usefulness. Keywords: ABI, ankle brachial index, Coronary angiogram, Peripheral vascular disease, Chronic total occlusion, Coronary artery disease, Diabetes. Thai Heart J 2008; 21 : E-Journal : Introduction Atherosclerosis is a generalized disease and several of its manifestations may coexist in the same patient. Previous studies have shown that patients with symptomatic or asymptomatic peripheral arterial disease often present with coronary atherosclerosis and are at an increased risk for adverse cardiovascular events (1, 2). The resting ankle-brachial pressure index (ABI) is a noninvasive method to assess the patency of the lower extremity arterial system and to detect the presence of arterial occlusive Correspondence: Sittiluck Wongwantanee, MD Division of Cardiology, Faculty of Medicine Siriraj Hospital, Mahidol University E mail: jojotu@hotmail.com disease (3, 4). ABI has been shown to be a strong predictor of subsequent cardiovascular events in patients with peripheral vascular disease (5). Many studies (6-8) have reported an association between ABI and coronary heart disease which can all cause mortality. The usefulness of ABI in subjects with angiographically proven coronary artery disease (CAD) is limited. This study evaluates the relationship between ABI and the extent of coronary atherosclerosis in Thailand. It was our aim to evaluate the sensitivity and specificity of a diagnosis of ABI as a predictor of the extent of coronary atherosclerosis in patients with CAD. Methods We performed an analytical descriptive study on 326 consecutive patients who were suspected of having

2 Sittiluck Wongwantanee, MD CAD that underwent elective coronary angiography at Siriraj Hospital form January 2005-December Baseline cardiovascular risk factor characteristics were collected according to the ACC/AHA2002 guidelines for risk factors of CAD with a routine questionnaire before the procedure. All data w were acquired by chart review. Significant atherosclerosis of coronary arteries was defined as a reduction in the luminal diameter of 50% in 1 or more coronary arteries. The extent of coronary arteries involved was defined as follows: 1. Significant CAD comprised patients with significant atherosclerosis of at least one coronary artery. 2. Single vessel disease comprised patients with atherosclerosis of one coronary artery. 3. Double vessel disease comprised patients with atherosclerosis of two coronary arteries. 4. Triple vessel disease comprised patients with atherosclerosis of three coronary arteries. 5. Left main artery (LM) disease comprised patients with significant atherosclerosis at the main branch of the left coronary artery before bifurcation of the left circumflex and left anterior descending artery. 6. LM plus 3 vessel diseases comprised patients with atherosclerosis of three coronary arteries or left main branch with most of this group eventually proceeding to coronary artery bypass graft surgery (CABG). 7. Chronic total occlusive comprised patients with100% stenosis in one of the coronary arteries which in this group meant a poorer percutaneous coronary intervention outcome. 8. Proximal left anterior descending artery (LAD) lesion comprised patients with significant atherosclerosis of the proximal left anterior descending artery before bifurcation of the first diagonal branch. Ankle-brachial index (ABI) was performed in the supine position after 5 minutes rest using Vasera VS Patients were defined as having an abnormal ABI if the ABI was lower than 0.9 in at least one limb. Significant severe peripheral artery disease was suspected if the ABI was lower than 0.7 in at least one limb. Peripheral artery angiography was performed in some selected patients who had an abnormal ABI and agreed to undergo peripheral angiography after completion of coronary angiography. Imaging was obtained mostly at the ilio-femoral level. Bolus chasing angiography was done in some cases. Significant atherosclerosis of peripheral arteries was diagnosed by 50% diameter reduction of the luminal diameter. The study was approved by Siriraj Hospital Ethics Committee and performed in accordance with the Helsinki Declaration of Human Rights. Statistical Analysis Patient characteristics are presented as percentage of variables. Continuous data is expressed as mean ± SD. Median with interquartile ranges was used when the variables are not normally distributed. The association of ABI values with the extent of CAD was examined by Analysis Of Variance (Tamhane s T2 post hoc multiple comparision). The Chi-square test was used to compare categorical variables. The continuous variables are presented as median and interquartile ranges if normally distributed and expressed as mean ± SD. Results Study population and angiographic results A total of 326 patients were included in this study. Baseline characteristics and coronary risk factors are shown in Table 1. The mean age was 64 ± 12 yr. The Majority of our patients were at a high risk for CAD with a mean number of cardiovascular risk factors being 3.3 ± 1.3. Two hundred and ninety six patients (90.8%) had significant coronary artery disease. The extent of CAD is shown in Table 2. More than half of our patients had a severe form of CAD and 49% of patients had a triple Table 1. Baseline patient characteristics N % Aged >65 years Male Diabetes mellitus Hypertension Dyslipidemia Family History of CAD smoking previous CABG previous PCI

3 Usefulness of an Abnormal Ankle-Brachial Index to Predict the Presence of Coronary Artery Disease vessel disease or left main lesion that needed a further CABG operation. Ankle-brachial Index results 67 patients (20.5%) had positive ABI measurement 0.9 and 19 patients (5.8%) were positive at a value 0.7. Regarding the vascular risk factors that were tested by multiple logistic regression analysis, only age > 65 yr (p=0.002) and diabetes mellitus (p = 0.024) Table 2. Baseline angiographagic results N % Significant CAD vessel vessels vessels Non significant CAD LM disease LM + 3-vessel disease Proximal LAD lesion Total occlusion were related independently to ABI (Table 3). Severity of peripheral artery occlusive disease was associated with the angiographic severity of CAD (Table 4). But in a different type of coronary artery lesion chronic total occlusion and a proximal left anterior descending lesion were not associated with an abnormal ABI (Table 5). Among all patients with CAD an abnormal ABI had low sensitivity (22-31%) but high specificity for detecting a severe form of CAD (68-77%). At the lower ABI value ( 0.7) a lower sensitivity was observed but the specificity potentates at this value (Table 6). Peripheral angiographic results Sixty-seven patients (96 limbs) had positive ABI, Thirty -three patients (51 limbs, 53%) underwent peripheral angiography. Twenty patients had 3 levels of peripheral angiograms (Iliofemoral, femoro-popliteal, and infra popliteal level) performed. Eighty percent of patients (27 patients) or seventy-two percent of limbs (37 limbs) that had abnormal ABIs also had significant peripheral artery stenosis. Sixtyeight percent (22 patients) or seventy-eight percent of limbs (29 limbs) had ilio-femoral artery involvement. Table 3. Baseline Patients Characteristics and ABI value Total n= 326 patients ABI 0.9 ABI > 0.9 P-value OR 95%CI Aged>65 (n=221, 67.8%) Male (n=211, 64.7%) Diabetes (n=125, 38.3%) Hypertension (n=222, 68.1%) Dyslipidemia (n=213, 65.3%) Family history (n=19, 5.8%) smoking (n=58, 17.8%) previous CABG (n=22, 6.7%) previous PCI (n=105, 32.2%) Table 4. The association between severity of CAD and abnormal ABI No CAD 1 Vessel 2 Vessel 3 Vessel P-value ABI mean ± SD 1.06 * ± ± ± * ± ABI, ankle brachial index; CAD, CAD; 1 Vessel, single vessel disease; 2 Vessel, double vessel disease; 3 Vessel, Triple vessel disease. (P<0.05 for difference between groups. * significant between group)

4 Sittiluck Wongwantanee, MD Table 5. The association between different types of coronary artery disease and abnormal ABI N ABI p value Mean ± SD significant CAD No ± Yes ± Triple vessel disease No ± Yes ± LM disease No ± Yes ± Proximal LAD No ± Yes ± 0.15 Chronic total occlusion No ± Yes ± Triple vessel + LM No ± Yes ± Table 6. The sensitivity and specificity of abnormal ABI to detect coronary artery disease severity ABI 0.9 Sensitivity Specificity ABI 0.7 Sensitivity Specificity Significant CAD (n=296, 90%) LM disease (n=48,14%) Triple vessel (n=143, 43%) Triple vessel + LM (n=160, 49%) ABI, ankle brachial index; CAD, coronary artery disease; LM, left main branch of left coronary artery. Discussion Atherosclerosis is a global disease with several manifestations. ABI is an inexpensive non-invasive test for the diagnosis of peripheral atherosclerosis and is easily applied in any ambulatory clinic. It has been used either in clinical practice or in an epidemiologic study as an index of peripheral arterial disease (2). A diagnosis of an abnormal ABI has been proven to be a valuable predictor of systemic vascular disease (9, 10) associated with high atherogenic risks for CAD (11, 12). Previous retrospective studies have shown an association between abnormal ABI and the degree of CADs in Hispanics and Europeans (13, 14). Our study also shows the same correlation between abnormal ABI and the extent of CAD in the Thai population; especially in that the lower ABI is correlated with the severity of coronary artery disease and not the type of coronary morphology. In analyzing the results, chronic total occlusions and proximal LAD stenosis did not correlate with the degree of ABI itself while the number and extent of coronary disease, such as single- 2 or 3- vessels, left main disease or left main together with 3 vesseldisease was clearly correlated. We found that the sensitivity of the ABI measurement was 22.3% and the specificity 77.0% in detecting significant CAD. Those with a more severe form of CAD had a wider sensitivity (23-31%). Diabetes had a higher sensitivity and specificity (28.5 vs. 100%). In current clinical practice, percutaneous coronary intervention (PCI) and CABG are treatments of choice for patients with CAD. CABG are more favorable among left main and triple vessel disease (15) especially among diabetics according to the ACC/AHA 2002

5 Usefulness of an Abnormal Ankle-Brachial Index to Predict the Presence of Coronary Artery Disease Guidelines (15). An abnormal low ABI is correlated with more severe CAD. In this study patients with lower ABIs were prone to undergo a CABG procedure due to their 3 vessel-cad or left main lesion state. Femoral artery disease was affected by atherosclerosis quite often (16), probably because of the vascular curvature existing in the femoral site (17). An abnormal ABI was correlated to significant peripheral arterial occlusive diseasewith78% of those with an abnormal ABI having ilio-femoral artery stenosis. This led to further percutaneous intervention. Complications such as tortuous exit vessel (superficial femoral artery, common iliac artery, descending aorta) and easily dissecting atheromatous plaque have poorer intermediate outcomes (20) among patients undergoing coronary revascularization such as PCI or CABG. The interventionist may use an abnormal ABI to predict a more severe form of CAD which enables more meticulous care to avoid complications prior to the procedure and also have the equipment well prepared. Transradial coronary angiography may be a preferable choice in a positive ABI patient. Patient and relative counseling could also be performed prior to the procedure. However, the applicability of ABI is limited due to its rather low sensitivity but high specificity. Furthermore an abnormal ABI was also an adverse longterm strong marker of cardiovascular morbidity and mortality outcomes in patients undergoing CABG (18, 19). References 1. MH C. Peripheral arterial disease and subsequent cardiovascular mortality: a strong and consistent association. Circulation 1990; 82: Criqui MH LR, Froneck A, Feigelson HS, Klauber MR, McCann TJ, Browner D. Mortality over a period of 10 years in patients with peripheral arterial disease. N Engl J Med 1992; 326: Hiatt WR HS, Hamman RF. Effect of diagnostic criteria on the prevalence of peripheral arterial disease. Circulation 1995; 91: Carter SA. Indirect systolic pressures and pulse waves in arterial occlusive disease of the lower extremities. Circulation 1968; 37: Sikkink CJ, Van Asten WN, Van t Hof MA, Van Langen H, Vander Vliet JA. Decreased ankle-brachial indices in relation to morbidity and mortality in patients with peripheral arterial disease. Vascular Medicine 1997; 2: Vogt MT, Cauley JA, Newman AB, Kuller LH, Hulley SB. Decreased ankle/arm blood pressure index and mortality in elderly women. J Am Med Assoc 1993; 28: Kuller LH SL, Psaty BM, Borhani NO, et al. Subclinical disease as an independent risk factor for cardiovascular disease. Circulation 1995; 15: Resnick HE LR, McDermott MM, Devereux RB, Jones KL, Fabsitz RR, Howard BV. Relationship of high and low ankle brachial index to all-cause and cardiovascular disease mortality: the Strong Heart Study. Circulation 2004; 17: Espinola-Klein C RH, et al. Manifestation of atherosclerosis in various region. Similarity and difference regarding epidemiology and prognosis. Med Klin 2002; 97: Cimminiello C. Peripheral arterial disease as a global vascular risk factor. Haematologica 2001; 86: Newman AB SD, et al. Ankle arm index as a marker of atherosclerosis in the Cardiovascular Health Study. Circulation 1993; 88: Zheng ZJ, Sharrett AR, Chambless LE. Association of anklebrachial index with clinical coronary heart disease, stroke and preclinical carotid and popliteal atherosclerosis: The Atherosclerosis Risk in Communities (ARIC) study. Atherosclerosis 1997; 131: Aronow WS, Ahn C. Prevalence of coexistence of coronary artery disease, peripheral arterial disease, and atherothrombotic brain infarction in men and women_62 years of age. Am J Cardiol 1994; 74: Mendelson G AW, Ahn C.. Prevalence of coronary artery disease, atherothrombotic brain infarction, and peripheral arterial disease: associated risk factors in older Hispanics in an academic hospital-based geriatrics practice. J Am Geriatr Soc 1998; 46: Gibbons RJ AJ, Abrams J, Chatterjee K, et al. ACC/AHA 2002 guideline update for the management of patients with chronic stable angina. J Am Coll Cardiol 2003; 41: Magnien JL SV, Jeannin S, Hernigoy A, Plainfosse MC, Merli I. Coronary calcification and its relation to extracoronary atherosclerosis in asymptomatic hypercholesterolemic men. Circulation 1992; 85: Smedby O, Nilsson S, Bergstrand L. Development of femoral atherosclerosis in relation to flow disturbance. J Biomech 1996; 29: Bell MR, Gersh BJ, et al. Effect of completeness of revascularization on long term outcome of patients with three vessel disease undergoing coronary artery bypass surgery: A report from the coronary artery surgery study (CASS) Registry. Circulation 1992; 86: The BARI Investigation: Seven years outcome in the Bypass Angioplasty Revascularization Investigation (BARI) by treatment and diabetic status. J Am Coll Cardiol 2000; 35: O Rourke DJ, Quinton HB, Piper W, et al. Survival in patients with peripheral vascular disease after percutaneous coronary intervention and coronary artery bypass graft surgery. Ann Thorac Surg 2004; 78:

6 Sittiluck Wongwantanee, MD ประโยชน ของการใช Ankle brachial index (ABI) ในการทำนายโรคหลอดเล อดแดง โคโรนาร ส ทธ ล กษณ วงษ ว นทน ย, พบ., ดำร ส ตร ส โกศล, พบ., กมล อ ดล, พบ. สาขาหท ยว ทยา ภาคว ชาอาย รศาสตร คณะแพทยศาสตร ศ ร ราชพยาบาล บทค ดย อ ภ ม หล ง: ค า ABI (Ankle brachial index) เป นด ชน ท เก ดจากอ ตราส วนของความด นซ สโตล ก ของแขนและขา, สามารถใช ว น จฉ ยโรคหลอดเล อดแดงส วนปลายต บต น (peripheral artery disease) ได การศ กษาท ผ านมาแสดงให เห นว าคนไข โรคหลอด เล อดแดงส วนปลายต บต นไม ว าจะม หร อไม ม อาการจะเพ มความเส ยงของโรคหลอดเล อดห วใจโคโรนาร การศ กษาน ต องการ ศ กษาความส มพ นธ ของโรคหลอดเล อดห วใจโคโรนาร จากการฉ ดส หลอดเล อดห วใจ (coronary angiogram) ก บโรคหลอด เล อดแดงส วนปลายต บต นโดยใช ค า ABI ว ธ การและผลการศ กษา: การศ กษาน เก บข อม ลของคนไข ท ถ กน ดมาทำการฉ ดส หลอดเล อดแดงห วใจ (Coronary angiogram) ท หน วยหท ยว ทยาโรงพยาบาลศ ร ราช ท งหมด 326 คน ต งแต ว นท 1 มกราคม ถ ง 31ธ นวาคม 2548 โดยเก บข อม ลพ นฐาน คนไข, ความเส ยงของโรคหลอดเล อดห วใจ, ผลของการฉ ดส หลอดเล อดแดงโคโรนาร, ผลการฉ ดส หลอดเล อดส วนปลาย (Peripheral artery angiogram) และค า ABI พบว าค าABI ท ผ ดปกต ม ความจำเพาะ (specificity) ส ง (77%) สำหร บโรคหลอดเล อดแดงต บต นแบบร นแรง(triple vessel or left main disease) แต ม ค าความไวในการว น จฉ ย (sensitivity) ต ำ (22%) ค าความไวจะส งข นถ าใช ร วมก บความเส ยง ของโรคหลอดเล อดห วใจเช น เบาหวาน (sensitivity 25%) อาย มากกว า 65ป (sensitivity 27%) และย งพบอ กว าล กษณะรอย โรคเช น รอยโรคท left main และการม จำนวนของรอยโรคในหลอดเล อดแดงโคโรนาร ท มากข นม ความส มพ นธ ก บค า ABI ท ต ำลง แต รอยโรคท proximal left anterior descending artery หร อ รอยโรคแบบ chronic total occlusion ไม ม ความส มพ นธ ก บค า ABI ในคนไข ท ม ค า ABI ผ ดปกต ท งหมด 67 คนได ร บการฉ ดส หลอดเล อดส วนปลาย (Peripheral artery angiogram) 33คน (51 ข างหร อ 51%) พบว า 27คน (37ข าง หร อ 80%) ม ภาวะหลอดเล อดส วนปลายต บต นและในน พบการต บต นท ระด บ ilio-femoral artery ถ ง 78% (29 ข าง) สร ป : พบว าค า ABIท ผ ดปกต ม ความส มพ นธ ก บความร นแรงของโรคหลอดเล อดแดงโคโรนาร ค า ABI ม ค าความ จำเพาะ(specificity)ส งในการทำนายโรคหลอดเล อดแดงโคโรนาร แต ม ค าความไว(sensitivity) ต ำ จากการท พบว าคนไข ท ม ค า ABI ท ผ ดปกต จะพบการม รอยโรคท ระด บ ilio-femoral ส งและรอยโรคท โคโรนาร ม กจะเป นแบบร นแรงโดยเฉพาะในคนไข ท ม ค า ABI ท ต ำมากๆ เพราะฉะน นค าABIน าจะเป นเคร องม อแบบnon-invasive ท ม ประโยชน สำหร บinterventionist ในการ เตร ยมคนไข ท ม ความเส ยงส งก อนการทำ coronary angiogram และ percutaneous coronary artery intervention อย างไรก ด ABI ม ข อจำก ดในเร องของความไวท ต ำ