Q J Med 1999; 92: 219-222
© 1999 Association of Physicians
Cholesterol in peripheral vascular disease—a suitable case for treatment?
From the Department of Cardiology, Western Infirmary, Glasgow and 1Directorate of General and ENT Surgery, Gartnaval General Hospital, Glasgow, UK
Received 22 October 1998 and in revised form 3 February 1999
Dr A.L. Clark, Department of Cardiology, Western Infirmary, Dumbarton Road, Glasgow G11 6NT. e-mail: ALClark1{at}compuserve.com
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Summary |
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We assessed the prevalence of conventional risk factors for ischaemic heart disease in patients with peripheral vascular disease, and the scope for preventative treatment with lipid-lowering therapy in this group, by retrospectively reviewing 299 patients who had undergone peripheral angiography in 1996. A total of 278 patients had severe peripheral vascular disease; 44% were current smokers at the time of their angiogram, and 36% had a history of coronary artery disease (either myocardial infarction, coronary artery bypass surgery, coronary angioplasty or angina). Cholesterol had been measured in 80 (27%) patients, of whom 26 (9%) were receiving treatment for hypercholesterolaemia. Patients with a history of ischaemic heart disease were more likely to have had their cholesterol measured (50% vs. 15%; p<0.001). Hypertension (defined as systolic >160 mmHg or diastolic >90 mmHg) was present in 44%. There was no difference in the distribution of risk factors between those with and those without known ischaemic heart disease. There is a high prevalence of modifiable risk factors for coronary disease in patients with severe peripheral vascular disease. Effective prevention is available for coronary artery disease, but we found low levels of treatment. There is considerable scope for intervention to reduce the risk of coronary disease in such patients.
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Introduction |
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Recent large-scale clinical trials have demonstrated beyond doubt the potential benefit of cholesterol-lowering in patients with ischaemic heart disease using HMG CoA reductase inhibitors.1,2 There remains debate as to when intervention is indicated in an asymptomatic population in terms of the cost-benefit analysis. The natural history of peripheral vascular disease (PVD) is of a high mortality, related predominantly to the development of ischaemic heart disease.3 It is not yet known whether intervention to reduce lipids is effective in this group.
Patients with PVD usually have coronary disease, often silent. Such patients are at high risk and are a potential target for prevention strategies. We analysed the records of patients who underwent angiography for symptomatic peripheral vascular disease for the presence of concomitant ischaemic heart disease and conventional risk factors for coronary heart disease. We wanted to estimate the present level of treatment, particularly of hypercholesterolaemia, and assess the possible scope for coronary prevention.
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Methods |
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The records of all patients undergoing peripheral angiography during the calendar year 1996 were identified from the radiology department computer database. Patients undergoing angiography are a highly selected group, having undergone non-invasive tests to establish the presence of potentially treatable disease. The overwhelming majority were thus pre-selected as having severe PVD. Severe disease was recorded where there were occlusions or tight stenoses reported by the radiologist.
The case notes were drawn and analysed. For each patient file, a form was completed using data recorded at the admission for the angiogram and information reported in correspondence to the patients' general practitioners. We recorded information regarding conventional risk factors: smoking history, past history of hypertension, diabetes, heart or cerebrovascular disease, family history and drug history. We also recorded whether a cholesterol estimation was in the notes within a year of the angiogram. Contemporary ECGs were available for analysis in 92% of patients.
Past cardiac history was defined as history of angina, myocardial infarction or heart failure, or the presence of pathological Q waves on ECG, where available. Results are reported as means±SD.
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Results |
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Overall, 299 patients had undergone angiography for peripheral vascular disease, mean (SD) age 66.2±10.3 years. The women (n=131) were significantly older than the men (68.4±10.3 years vs. 64.5±10.0; p<0.001). Of these patients, 10 had normal vessels, 11 had mild disease, and the rest (93%) had angiographically severe disease. The management of the peripheral vascular disease is shown in Table 1
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A total of 80 patients had had their cholesterol measured, with an average of 6.12±1.13 mmol/l (range 4.04–10.3). Figure 1
shows the distribution of cholesterol measurements. Of these patients, 26 were receiving treatment for hypercholesterolaemia, 24 with an HMGCoA reductase inhibitor. The cholesterol was 6.29±1.03 in the treated group and 6.05±1.18 in the untreated (p=NS). Of those with a cardiac history (see below), 52 (49%) had had their cholesterol measured. Cholesterol was 5.97±1.01 in the cardiac history group and 6.41±1.30 in the rest (p=NS), but patients in the cardiac history group were much more likely to have had their cholesterol measured (50% vs. 15%; 
2=43.7; p<0.001). In the two groups, 21 and 14 patients, respectively, were being treated with cholesterol-lowering drugs (20% vs. 7%; 2=10.4; p=0.001).
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The smoking history of the patients is documented in Table 2
. Overall, 44% were still current smokers at the time of their angiogram compared with 35% for the population of Scotland as a whole.4 Advice to stop smoking was recorded in the notes of 81 (62%) of current smokers.
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The Venn diagram (Figure 2
) shows the numbers of patients with a clinical history of myocardial infarction and angina or intervention for coronary artery disease. A total of 106 patients (35.5%) had had clinical evidence of coronary heart disease (either myocardial infarction, CABG, coronary angioplasty or angina). In addition, a further four patients had a history of heart failure, and 22 patients had evidence of myocardial infarction on ECG.
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Risk factors
The distribution of other risk factors is shown in Table 3
and Figure 3. There was no significant difference in the distribution of risk factors between the group of patients with a cardiac history and those without. Blood pressure at the time of admission for angiography was recorded in 283 patients and was 147.6±24.6/81.8±14.2 mmHg. Hypertension (defined as systolic pressure >160 or diastolic >90) was present in 133 patients, of whom 61 were receiving no anti-hypertensive medication. There was no difference in blood pressure between those on treatment and those not (168.0±20.7/91.9±13.6 vs. 164.0±20.4/92.6±9.4).
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Drug use
Aspirin was being taken by 140 patients (70 of those 106 with a cardiac history, 13/18 with previous CVA/TIA). In total, 34 patients were receiving a beta blocker (but only 7 of those 57 with previous myocardial infarction), 34 a thiazide, and 84 a calcium antagonist.
Mortality
Although this study was not designed to examine the question of mortality, we were able to determine survival; as at the end of September 1997, 29 patients (10%) were known to have died. The cause of death was directly due to ischaemic cardiac problems in 13, and to peripheral vascular disease in 10. Five of these deaths were within 2 weeks of the index peripheral arteriogram, and in these the cause of death was gangrene in two, myocardial infarction in two and pneumonia in the fifth.
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Discussion |
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Symptomatic peripheral vascular disease predominantly affects a population at high risk of developing coronary artery disease. Consequently, it is a condition with a high cardiac mortality. It may be that the time of diagnosis of peripheral vascular disease is an appropriate time to consider the prevention, primary or secondary, of ischaemic heart disease.
The population examined in this study had undergone angiography on the basis of symptoms of claudication and positive non-invasive tests for peripheral vascular disease. It is thus not surprising that almost all the patients had significant PVD at angiography.
Fully 35% of these patients had evidence of established coronary heart disease in whom consideration of secondary prevention by lipid management should be considered. Of these, cholesterol had been measured in just under half, and pharmacological treatment instituted in 20%. We also found a substantial prevalence of hypertension and a high prevalence of conventional risk factors for coronary artery disease.
Patients with peripheral vascular disease represent a population at high risk of future cardiac events. Effective treatment for secondary prevention is available, although not fully used, even in patients with established ischaemic heart disease.5 Whether lipid-lowering therapy is effective at reducing cardiac events in patients with PVD with no antecedent cardiac history is not known. Previous studies have been small, and although not conclusive, suggest a fall in mortality with cholesterol reduction in PVD,6 but this needs to be researched further. Aspirin reduces risk in PVD,7 and we were disappointed that less than half of the patients were receiving aspirin. The diagnosis of PVD should prompt a thorough search for risk factors in an individual patient and consideration of preventative intervention.
This is a retrospective study and refers to a highly selected group of patients. We wanted to be certain that we were studying patients with proven, rather than presumed, PVD, so have studied only that minority of PVD patients who underwent angiography. We cannot be certain that the results are applicable to the general population of PVD patients. A further confounder is that we cannot know whether a large proportion of patients had had their cholesterols measured by their general practitioner. However, there were no patients taking a lipid-lowering agent for whom there was not a cholesterol estimation in the notes, suggesting that this is unlikely to be a major limiting factor. The mortality data reported here are not exhaustive, and refer only to those patients we know to have died.
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References |
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1. Scandinavian Simvastatin Survival Study Group. Randomised trial of cholesterol lowering in 4444 patients with coronary heart disease: the Scandinavian Simvastatin Survival Study. Lancet 1994; 344:1383–9.[Web of Science][Medline]
2.
Sacks FM, Pfeffer MA, Moye LA, Rouleau JL, Rutherford JD, Cole TG, Brown L, Warnica JW, Arnold JMO, Wun C-C, Davis BR, Braunwald E for the Cholesterol and Recurrent Events Trial Investigators. The effect of pravastatin on coronary events after myocardial infarction in patients with average cholesterol levels. N Engl J Med 1996; 335:1001–9.
3. Criqui MH, Langer RD, Fronek 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; 326:381–6.[Abstract]
4. The Scottish Office. Scotland's Health. Scottish Health Survey 1995. Edinburgh, The Stationery Office, 1997.
5.
ASPIRE steering group. A British Cardiac Society survey of the potential for the secondary prevention of coronary disease: ASPIRE (Action on Secondary Prevention through Intervention to Reduce Events). Heart 1996; 75:334–342.
6. Leng GC, Price JF, Jepson RG. Lipid-lowering therapy in lower limb atherosclerosis (Cochrane Review). In: The Cochrane Library, Issue 4, 1998. Oxford, Update Software, 1998.
7. Antiplatelet Trialists' Collaboration. Collaborative overview of randomised trials of antiplatelet therapy—I: Prevention of death, myocardial infarction, and stroke by prolonged antiplatelet therapy in various categories of patients. Br Med J 1994; 305:81–106.
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