Vascular morbidity and mortality during long-term follow-up in claudicants selected for peripheral bypass surgery

Eur J Vasc Endovasc Surg 16, 292-300 (1998)

Vascular Morbidity and Mortality During Long-term Follow-up in Claudicants Selected for Peripheral Bypass Surgery I. D a w s o n .1, R. B. Sie 2, E. E. van der Wall 3, R. Brand 4 and J. H. van Bockel 1 1Department of Surgery, 2Department of Anaestheszology, 3Department of Cardzology, and eDepartment of Medzcal Statzstics, Universzty Hospztal Lezden, The Netherlands Objectives: to zdentzjiy clau&cants at hzgh rzsk (and low risk) of late vascular morb~&ty and mortahty after perzpheral bypass surgery. Design: prospecttve cohort study with mean follow-up of 8 6 years Patients: one-hundred and f~fty-f~ve claudicants selected for perzpheral bypass surgery. Only three patzents were lost to follow-up. End points were ma}or vascular events, ad&twnal znterventwns, all-cause mortahty, and functwnal outcome. Results: major vascular events occurred zn 59 patzents. Life-table analyszs revealed an annual risk zncrease of 3 5%. Strong predzctors were hypertenswn (hazard ratzo (HR) 2.7; 95% condidence zntervaI (CI) 1 5-4.8), dzabetes (HR 2 4, 95% CI 1.0-5 4) and cardzac dzsease (HR 2.2, 95% CI 1.2-4.0) Sixty patients needed addztwnal interventzons w#h a hzghest mczdence (17%) m the f~rst year, and thereafter 2 8% each year None of the known rzsk factors were assoczated with an altered znczdence of mterventzons Approxzmately 3.5% of patients dzed per year compared wzth 2% per year zn the control group. Prominent hzgh-rzsk factors for mortality were cardzac dzsease (HR 3.3; 95% CI 1 8-6.0) and dzabetes (HR 3 O; 95% CI 1 5-7.1). Conclusion: major vascula, events and ad&twnal mterventzons are common and serwus in claudicants. However, zt zs possible to select Iow-rzsk patzents in wluch perzpheral bypass surgery zs just~ed Key Wo, ds: Intermzttent clau&catwn; Cardzovascular dzsease; Mortahty, Morbzd#y, InframguznaI bypass, Reoperatwn, Funct~onaI outcome.

Introduction

It is generally assumed that mtermittent claudication caused by femoral atherosclerosls is a relative indlcation for peripheral bypass surgery, because the natural history of the disease is characterised by a low risk of limb-loss and a high risk of cardiovascular death. 1'2 This assumption supports an initial conservative approach to most patients with intermittent claudlcation; structured exercise programs are valuable, and modification of risk factors, especially cessation of smoking, is widely advocated. 3'4 Satisfactory results by conservative treatment, however, can take as long as a year, and complete relief of symptoms of leg ischaemia is rare. s'6 Nowadays, an increasing number of patients do not accept the limitations in physical and social activity caused by intermittent claudlcation7 and surgical intervention is requested. The rationale to these requests relates to the immediate, * Please address all correspondence to I Dawson, Department of Surgery, IJsselland Zlekenhuls, PO Box 690, 2900 AR Capelle aan de IJssel, The Netherlands

1078-5884/98/100292+09 $12 0 0 / 0 0

consistent, and often long-term Improvement in symptoms resulting from bypass surgery in terms of exercise performance and community-based walking ability, s These benefits of surgery support a relaxation toward the indications for investigation and intervention of claudicants. 6'9 On the other hand, it is important to realise that claudicants selected for peripheral bypass surgery may require additional arterial interventions for symptoms of recurrent limb lschaemla caused by new occlusive lesions or late complications of the initial su~'gical reconstruction. Even more Important is the high risk of cardiovascular morbidity and mortality caused by associated lschaemic heart disease. I°-13 In practice, however, not all patients with intermittent claudication face comparable long-term risk, and it becomes increasingly Important to stratify patients by relative risk of an adverse clinical outcome. To redefine the indications for surgery in patients with intermittent claudication we determined the longterm risk of mortality, major vascular events, and need for additional interventions. In addition, this study assessed the changes in self-reported walking ability,

1998 WB Satmders Company Ltd

Late Vascular Events in Claudicants

Table 1. Patient characteristics at the time of bypass surgery, Characterlshc

No

Age, y (mean±s D) Male gender Hypertension

58±10

Diabetes melhtus Smoking Cardiac &sease Cerebrovascular &sease

144 45 18 149 50 8

Previous vascular surgery

62

% 93 29 12 96 32

5 4o

i.e. functional outcome, following bypass surgery. Finally, the impact of coexistant cardiac disease and other prognostic factors on the occurrence of adverse events was evaluated,

Material and Methods

Study population The vascular registry in the Department of Surgery at Leiden University Hospital was examined to identify patients with intermittent claudicahon treated with an mfrainguinal bypass. Since intermittent claudication is at most a relative indication for vascular reconstruction, only 155 consecutive patients underwent infrainguinal bypass surgery for disabling claudication between 1958 and 1988. Especially in the last decade, these patients account for no more than 10% of patients undergoing peripheral bypass surgery in our institution. The deosion to offer surgery was not only based on the severity of claudication, but also on other factors such as age of the patient, risks of surgery, favourable anatomic location of lesions, and failure of conservative treatment. This conservative regimen, of at least 6 months' duration, consisted of risk factor modification in an attempt to decrease cardiovascular morhidity and mortality; unsupervised exercise training to increase pain-free walking time; and finally treatment with oral anticoagulants to reduce the incidenceofischaemicevents. Ninety-two patients (59%) had a walking distance of less than 100 m and were categorised as severe claudicators, and 63 patients (41%) had a walking distance of 100-500 m and were categorised as moderate claudicators. There were 144 men and 11 women, with a mean age of 58 years (range 27-79) at time of surgery (Table 1). Hypertension was present in 45 patients (45/155; 29%), and 18 patients (16/155; 12%) had &abetes mellitus. Most patients were current or former cigarette smokers (149/155; 96%). Coexistent vascular disease was common (Table 1). At time of the bypass 50

293

patients (50/155, 32%) had o n e o r m o r e climcal markers of cardiac disease: 22 patients (22/155; 14%) had a history of previous myocardial infarction, 19 patients (19/155; 12%) had symptoms of angina pectoris, 21 pahents (21/155; 14%) were treated for congestive heart failure, and 22 patients (22/155; 14%) required therapy for symptomatic ventricular arrhythmia. In addition, eight patients (8/155; 5%) had a history of symptomatic cerebrovascular disease and 62 patients (62/155; 40%) had undergone vascular surgery or angioplasty in cerebral, coronary, or peripheral arteries (Table 1). Bypass surgery was performed using the reversed greater saphenous vein in 112 patients (112/155; 72%), and prosthetic grafts in the remaining 43 patients (43/ 155; 28%). In 54 patients (54/155; 35%) the distal anastomosis was made to the arteries below the level of the knee. Patients routinely had follow-up examinations at 1, 3, 6, and 12 months after the date of operation and thereafter yearly for the rest of their hves. In addition, patients and their family doctors were instructed to report immediately any cardiovascular a n d / o r cerebrovascular symptoms. The exammations during follow-up were directed not only to the evaluation of the vascular reconstruction and the limb, but also to other cardiovascular events. Data were rarely missing for the hard end points of this study, since standard evaluation forms or vascular worksheets were used prospectively to document any vascular or cardiovascular event with date, severity and outcome of each event. Moreover, a very high patient comphance resulted in an almost complete and long-term follow-up. Only three patients (3/155; 2%) were lost to follow-up due to emigration after 1, 2, and 15 months. Mean follow-up period for the whole study population was 8.6 years and ranged from 1 month to 28 years. All patients were treated lifelong with oral coumarin derivates after operation. The optimal therapeutic range of international normahsed ratios aimed at in these patients was between 2.8 and 4.8. Every effort was made to stop the patient's smoking, to control diabetes, and to reduce high diastohc and systolic blood pressure as rigorously as possible during follow-up. Emphasis on aggressive cholesterol-lowering therapy was given only in the last years of the study period.

End points The primary end point of this study was death from any cause. Secondary end points were major vascular event, or additional vascular intervention after the 30day postoperative period. A major vascular event was Eur J Vasc Endovasc Surg Vol 16, October 1998

I. Dawson et al.

294

the composite end p o m t of cardiovascular death, nonfatal myocardial infarction, non-fata] cerebral stroke, or coronary artery bypass surgery for ischaemic heart disease. An additional vascular intervention was defined as a surgical or radiological intervention over h m e for graft complications or deterioration of peripheral arterial disease. Functional results were analysed b y determining the walking capacity at any time period after operation. The presence of lschaemic s y m p t o m s in both extremities were included irrespective of the side of the infrainguinal bypass. Postoperatively, lschaemic s y m p t o m s were classified into one of the five categories of increasing levels of s e v e n t y - no symptoms, mild (walking distance more than 500 metres), moderate (walking &stance of 100500 metres), and severe claudication (walking &stance of less than 100 metres) and critical limb ischaemia or amputation. The effects of additional vascular interventions were included for all the calculahons.

Risk for major vascular events ]~0] [105] 75%

All data were systematically stored in a computerised vascular data base. The Kaplan-Meier m e t h o d of lifetable analysis was used to estimate patient survival and the cumulative risk of adverse events after surgery as a function of time) 4 Patient survival was c o m p a r e d with the expected survival in the Dutch population (1880-1995) adjusted for age and sex b y use of the data base of the Central Bureau for Statistics, The Hague, The Netherlands. The log-rank test was used to compare the risk of events with respect to the absence or presence of clinical variables. In a multivariate approach the stepwise Cox proportional hazards m e t h o d was used to determine the i n d e p e n d e n t effect of potential risk factors on o u t c o m e ) 5The relative importance of associations studied is expressed as a h a z a r d ratio (HR) and 95% confidence interval (CI). Statmtical significance was defined as p<0 05.

[< [aa]

[21 [181

-

[-] [8]

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rI F" 5o% ~ 25%~

32%

I

41%

I

6a~

7

~-ff 38% j ~

26~o

r- Z -

~2-~,,,

p<0001 ~-F~ - ~ - F

0%

I [E45]

75%

1103

[17]

I [8]

[753

[30]

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649

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Statistical analysis

c19] [v21

~39~ ~ ;

27~ ~ JS-r-

~--~-J P <00Ol

I I I 5 10 15 Years after mframgumal bypass

(B) I 20

Fig. 1. Kaplan-Meler eshmates of the risk for major vascular events, accordmg to (A) car&ac disease, and (B) hypertension Numbers m bracketsindicate number of patients still at risk in each group at the beglrmmg of each time period (A) Cardiac disease. (~) yes, (--) no (B) Hypertension (--)yes, (--)no cardiovascular death (41/74; 55%). The c u m u l a h v e risk for either one of these events to occur increased from 20% at 5 years to 71% at 20 years after surgery, i.e., an annual risk increase of 3.5%. Claudlcants with a hmtory of cardmc disease (Fig la), or hypertension (Fig. l b ) w e r e more likely to develop major vascular events c o m p a r e d to claudicants without these comorbiditms. Diabetes (p>0.2), smoking (p>0.5), and previous vascular intervention (p>0.1) did not influence the occurrence of major vascular events (Table 2). Multivariate analysis revealed cardiac disease (HR 2.2; 95% CI 1.2-4.0; p<0.01), hypertension (HR 2.7; 95% CI 1.5-4.8; p<0.002), and diabetes mellitus (HR 2.4; 95% CI 1.0-5.4; p<0.05) as sigmficant and i n d e p e n d e n t predictors associated with a 2-3 hmes greater risk of major vascular events.

Results

Major vascular events Addztmnal vascular intervention Major vascular events occurred in more than one-third of the patients (59/155; 38%) at a m e a n duration of 93 months (range 1-277 months, medzan 62 months), The 74 events observed were non-fatal myocardial infarction (16/74, 22%), non-fatal cerebral stroke (8/ 74; 11%), coronary bypass surgery (9/74; 12%), and Eur J Vasc Endovasc Surg Vol 16, October 1998

A surprisingly high n u m b e r of additional vascular mterventions were required after peripheral bypass surgery. Sixty patients (60/155; 3 9 % ) u n d e r w e n t surglcal or radiological intervenhon for deteriorating ischaemia of the legs during long-term follow-up. The

Late Vascular Events in Claudicants

295

Table 2. Effect of potential risk factors on the incidence of major vascular events (univariate analysis).

p value*

All patients Hypertension No Yes Diabetes melhtus No Yes C~garette smoking No Yes Cardiac &sease No Yes Previous intervention No Yes

No

Major vascular events (%) 5y

10y

15y

20y

155

20

31

45

71

0.0005

110 45

14 38

27 54

39 70t

64 --

0 21

137 18

17 38

29 48t

44 --

70 --

0 72

6 149

20-t 20

20t 35

-46

-72

0 0005

105 50

14 32

26 41

38 71t

63 --

93 62

17 26

29 43

40 63

68 81t

0 18

*Only those differences with p<0.05 are considered significant, fthe standard error of the estimated risk exceeds 10% at this point m time

Table 3. Additional vascular interventions according to the ipsilateral and contralateral lower extremity.

Inframgumal bypass* Inframgumal non-bypasst Supramgumal proceduret Major amputahon$ Mmcellaneous§ Total

Ipsilateral No (%)

Contralateral No (%)

Total No. (%)

15 (18) 31 (37) 13 (16) 7 (8) 17 (20) 83 (100)

15 (33) 9 (20) 10 (22) 6 (13) 6 (13) 46 (100)

30 (23) 40 (31) 23 (18) 13 (10) 23 (18) 129 (100)

*Primary or secondary mframgumal bypass graft, tmterposmon graft, angloplasty with and without patch graft, and thromboembolectomy, Slower extremity amputation at below-knee or above-knee, §lumbar sympathectomy, toe or metatarsal amputation, and graft hgahon or exclslon

m e a n d u r a t i o n f r o m the inihal b y p a s s o p e r a t i o n to the first s u b s e q u e n t i n t e r v e n t i o n at lpsilateral or contralateral side w a s 51 m o n t h s (range 1-250 m o n t h s ; m e d l a n 23 m o n t h s ) . M o s t patients n e e d e d the i n t e r v e n t i o n w i t h i n 2 y e a r s after the initial o p e r a t i o n for claudication. A total of 129 p r o c e d u r e s w a s p e r f o r m e d , of w h i c h the m a j o r i t y o n p a t e n t p e r i p h e r a l b y p a s s grafts (Table 3). If m u l t i p l e p r o c e d u r e s w e r e p e r f o r m e d simultaneously, o n l y the p r o c e d u r e m o s t responsible or i m p o r t a n t to the overall effect w a s included. The 30d a y r e o p e r a t i v e m o r t a h t y w a s 2.3% (3/129) Thirteen limbs in 11 p a h e n t s (11/155; 7%) u l t i m a t e l y r e q u i r e d b e l o w or a b o v e - k n e e a m p u t a t i o n at a m e a n of 6.7 y e a r s f r o m the b y p a s s operation. T w e n t y - t h r e e p e r cent of the claudicants (36/155; 23%) n e e d e d v a s c u l a r s u r g e r y o n the contralateral side to gain relief f r o m

limb ischaemia. The n e e d for a d d i t i o n a l v a s c u l a r interv e n t i o n w a s 17% in the first y e a r a n d increased 2.8% p e r y e a r o n a v e r a g e o v e r the next 19 y e a r s (Fig. 2). H y p e r t e n s i o n , cardiac disease, diabetes mellitus, s m o k i n g a n d p r e v i o u s v a s c u l a r i n t e r v e n t i o n all failed to influence the n e e d for a d d i h o n a l v a s c u l a r s u r g e r y significantly.

Mortality N o deaths o c c u r r e d w i t h i n 30 d a y s after the operation. D u r i n g follow-up, 62 patients (62/155; 40%) d i e d at a m e a n d u r a t i o n of 109 m o n t h s (range 2-336 m o n t h s ; m e d i a n 78 m o n t h s ) . M y o c a r d i a l infarction (29/62; Eur J Vasc Endovasc Surg Vol 16, October 1998

I. Dawson

296

Risk for additional vascular interventions 75% --

[115]

[68]

[24]

[12] 69~,

50%-

.___; a a ~ '~

49% ~

,

[4] 72% F---J---

I

J 25% -d.rr ~

/

0%

0

I I I 5 10 15 Years after mframgumal bypass

I 20

Fig. 2. Kaplan-Memr estimates of the risk for additional interventions for all patmnts. Numbers m brackets m&cate number of patmnts stllI at risk m each group at the begmnmg of each time period (--)All patients. 4 7 ° ) , stroke (8/62, 13%) and other vascular events (4/ 62; 6%) accounted for a total of 66% of late death causes. The r e m a i n i n g 21 patients died of malignancies (15/62; 24%), respiratory disease (3/62; 5%) and sepsis (3/62; 5%) The o b s e r v e d survival estimates for claudicants selected for b y p a s s surgery at 5, 10, 15, and 20 years follow-up w e r e 82%, 66%, 53% a n d 36%, respectively. These survival rates are significantly poorer than the expected rates in the control group, In the univariate analysis of prognostic factors cardiac disease, diabetes, a n d h y p e r t e n s i o n at time of b y p a s s surgery w e r e associated w i t h a w o r s e survival (Table 4). Multivariate stepwise analysis identified cardiac disease and diabetes as significant a n d i n d e p e n d e n t

et al.

predictors of late mortality. Diabetic patients w e r e three times as likely to die as non-diabetic patients (HR 3.0; 95% CI 1 5-7.1, p<0.002), a n d patients w i t h cardiac disease h a d a m o r e than three-fold increased risk of d e a t h than those w i t h o u t cardiac disease (HR 3.3; 95% CI 1.8-6.0; p<0.0001). S u b g r o u p analysis of claudlcants w i t h o u t cardiac disease revealed a survival similar to the expected survival of the control g r o u p m a t c h e d for age a n d sex (Fig. 3a). Claudicants with overt cardiac disease h a d a w o r s e survival c o m p a r e d w i t h that of the control g r o u p (Fig. 3b).

functzonal outcome

Changes in self-reported walking ability during foll o w - u p is s h o w n in Fig. 4. In the majority of patients successful function, i.e. e n h a n c e m e n t of walking ability, w a s m a i n t a m e d t h r o u g h o u t the follow-up period. This i m p r o v e m e n t in quality of life w a s achieved regardless the d e v e l o p m e n t of limb ischaemia at ipsilateral or contralateral side of the infraingumal b y p a s s graft. The results w e r e better a n d could be m a i n t a i n e d at higher degree of success b y reoperation for failure or relapse of ischaemia. At 1 year of the b y p a s s operation 74% of the patients at risk w e r e s y m p t o m - f r e e w i t h full restoration of function. H o w e v e r , the chance of r e m a i n i n g free of s y m p t o m s declined steadily to 67%, 61%, a n d 56% at 10, 15, and 20 years, respectively. In addition to these rates of functional success, s o m e of the patients with mild or m o d e r a t e claudication

Table 4. Effect of potential risk factors on patient survival (univariate analysis).

p value*

All patients

No

Patient surwval (%) 5y

10y

15y

20y

155

82

66

55

36

Hypertensmn No Yes

0 05

110 45

85 78

68 60

61 29t

42 19t

Diabetes melhtus No Yes

0 05

137 18

85 69J-

69 31t

58 --

39 --

Cigarette smoking No Yes

0 59

6 149

80q 83

80t 65

80t 53

80-L 35

Cardtac disease No Yes

0 003

105 50

89 68

72 54

63 27

42 13

Previous intervention No Yes

0 88

93 62

83 84

65 67

56 45

37 30+

*Only those differences with p<0 05 are considered slgmficant ~-The standard error of the estimated risk exceeds 10% at thts point m time Eur J Vasc Endovasc Surg Vol 16, October 1998

Late Vascular Events in Claudicants

297

Discussion

Patient survival 100% ~

75% 50% 25%

(A) ~

~

~

s

3 ~

8

.

~

~ %

~

0%

~ P = NS I

I

I

I

100% ~ ~ ' ~ (B)

~".....vl~

75%

. 50% -

~

54~"

~

25% -

"--. 55~ - -

~

-. ~7~

~2~7////~

The treatment of intermittent claudication has b e e n the subject of considerable controversy over the years. To s o m e extent this can be explained b y a lack of explicit objectives for treatment. Is the a i m to save the leg, i m p r o v e quality of life or to p r o l o n g life, and if so, in w h a t w a y ? Several authors h a v e therefore e m p h a s i s e d the benign natural course of claudication w i t h respect to limb loss 16-:8 while others h a v e f o u n d surgical t r e a t m e n t w a r r a n t e d in v i e w of superior functional results. 6'19 C o n t r o v e r s y a b o u t the best m e t h o d of treatment could also be explained b y uncertainty a b o u t the l o n g - t e r m risks a n d complications after surgery. The p r i m a r y aim of the present s t u d y w a s to obtain reliable information that surgeons n e e d to discuss w i t h patients w h e n options for m a n a g e m e n t of intermittent claudicatlon are u n d e r consideration. For this p u r p o s e w e identified claudicants at high a n d low risk of late major vascular events, additional vascular

m ervon on and subsequent mor ai y 0%

0

, I y/////~//~A 5 10 15 Years after infrainguinal bypass

20

Fig. 3. Kaplan-Memr estimates of patmnt survival based on mortahty from all causes Control group matched for age and sex, and compared with (A) patmnts without eardmc dmease; (B) patmnts with overt cardiac &sease. Shadmg area re&cares the standard error Numbers m brackets indicate number of patmnts still at risk m each group at the beglnnmg of each time period (A) ( ) Controls, ( - ) claudlcants (n = 105) without cardmc disease, (B) ( ) controls, (--) claudlcants (n=50)wlthcardmc disease

h a d i m p r o v e d their p r e o p e r a t i v e w a l k i n g distance d u r m g follow-up and also benefited f r o m surgery. The p r o p o r t i o n of patients with critical limb ischaemia or a major a m p u t a t i o n increased to 6% at 20 years,

100% [155]

[103]

bypas

surgery. O u r study, however, h a d several limltat~ons that deserve comment. First, data collection relied on abstraction of medical records that occasionally w e r e incomplete or lacked documentation. By the use of standard evaluation forms, however, data w e r e rarely missing for the h a r d end points of this study. Second, as w i t h all longitudinal studies, investigation and treatm e n t of patients w i t h femoral atherosclerosis imp r o v e d during this 30-year period, w h i c h m a y h a v e influenced the findings of this investigation. Third, w e concentrated on a selection of patients w i t h intermittent claudication, i.e. those w h o h a d peripheral b y p a s s surgery; hence, our results cannot be extrapolated to all patients w i t h p e n p h e r a l artenal

[45]

[28]

[16]1

75% 50% 25%'

- -~

~

!

0% 0

5

10 15 Years after lnfraingumal bypass

20

Fig. 4. Changes m self-reported walkmg ablhty following mframgumal bypass surgery for intermittent clau&catlon Numbers m brackets indicate number of patmnts still at rink in each group at the begmnmg of each time period ( . ) Critical hmb lschaemla or amputation; ([]) severe elaudlcatlon; ([]) moderate claudmatlon, ([]) mild claudlcation; ([~) no complamts Eur J Vasc Endovasc Surg Vol 16, October 1998

I. Dawson

298

disease. Fourth, all patients were treated lifelong with oral anticoagulants, which may have influenced the incidence of long-term events, Finally, spare emphasis was given to cholesterol lowering therapy since patients were followed from the late 1950s until the present time, and support for aggressive cholesteroMowermg therapy as a component of secondary prevention ls provided by more recent clinical trials of statlns. 2°-22

Major vascular events As with all studies of intermittent claudlcatlon we have found a strong association with myocardial infarction and s t r o k e . 12'13'23'24 Most patients experienced this event withm 5-6 years, well within the average follow-up of 8.6 years. Life-table analysis showed that there was a cumulative risk of 3.5% each year during the 20 years of follow-up. Compared with patients treated for transient ischaemic attacks (TIA) of the brain or eye this is a low risk rate. In a cohort of hospital-referred patients an average risk of stroke, myocardial infarction or vascular death over the first 5 years after TIA was 6.5% per year and the average risk of stroke, myocardial infarction or death from any cause was 7.5% per yearY With the use of multivariate techniques we found that patients with independent clinical markers of cardiac disease, hypertension and diabetes were associated with a two-three-fold greater risk for major vascular events. These findings compare well with other s t u d i e s 12'13'23'24 and provide additional information to our previous reports regarding late cardiovascular events in patients selected for vascular surgery. ~1,26 Data from the Prevention of Atherosclerotic Complications with Ketanserin study on patients with claudication showed that hypertension and diabetes were predictors of mortality and of non-fatal myocardial infarction and stroke. ~4The importance of cardiac disease and diabetes is underlined in two comparable studies examining the late cardiovascular morbidity and mortality after lower extremity revascularisation ~2,~3In both studies, the projected annual risk of a cardiac event was between 7-8%. This high incidence is explained by the inclusion of patients with critical limb ischaemia alongside those with mtermittent claudication, although clearly the outcomes for such patients are markedly different.2'26'a7 Findings in the present study indicate that a lifelong surveillance for systemic complications of atherosclerosis is warranted, especially in the high-risk subgroups with diabetes, hypertension or cardiac disease, Eur J Vasc EndovascSurg Vol 16, October 1998

et al.

For the low-risk subgroups of claudicants without comorbid conditions we suggest a low-threshold for bypass surgery to rehef ischaemic symptoms of the lower extremities and improve the compromised lifestyle.

Add#ional vascular intervention As expected, most additional interventions occurred in the first 2 years after bypass surgery, which is the period in which most vein graft stenoses are initially detected. 28"29The mcreased occurrence of interventions in the first year is in agreement with studies examining the incidence of late reoperation in vascular surgery.29"3° In addition, our data support the contention that reoperation in vascular surgery is part of normal clinical practice. 29'31Although it appeared that requirement for additional interventions per se did not adversely affect the patients' perception of achieving a satisfactory result, 32 high-risk groups should be warned of the risks and consequences of reoperation. 29 The fact that in our study none of the known risk factors were associated with an altered incidence of intervention is difficult to explain, and may be the result of few numbers of patients. Nonetheless, the life-table curves show a non-significant trend to the detriment of patients with diabetes, hypertension or previous vascular interventions. Others indicate diabetes, continued cigarette smoking 33 and a low initial anklebrachial index 33 as strong predictors of disease progression and subsequent vascular intervention. 34'35

Mortality Our findings appear to be universal in patients with intermittent claudication. Many previous studies have reported an approximate doubling of the mortality rate among these patients 2,10,36-38 Mortality rates are further increased in patients with coexisting cardiac disease, 1'2'~2'38'39 diabetes, 2'12'a4'38 and advanced age, ~2'3g and in those who are smokers 39,40This series, however, was so dominated by current or former smokers, that demonstration of smoking as an independent predictor was not possible A major finding of this study was that the subgroup of patients without clinical evidence of cardiac disease appeared to have a normal life expectancy. This indicates that reconstructive surgery &d not adversely affect patient survival, and probably improve quality of life.

Late Vascular Events in Claudicants

Moreover, our findings strongly suggest that cardiac d i s e a s e s u s p e c t e d f r o m c o n v e n t i o n a l criteria (the hist o r y a n d e l e c t r o c a r d i o g r a p h i c f i n d i n g s ) c o u l d effectively stratify the i n c r e a s e d l o n g - t e r m risk of mortality in patients with intermittent claudication,

claudlcatlon) Prehmmary results from a prospective randomlsed trial Eur J Vasc Surg 1990, 4 135-140

6 LUNDGREN ][7 DAttLLOI~ AG, LUNDHOLM K, SCHERSTEN T, VOLK-

7 8

Functzonal outcome 9 The p r i m a r y c o n c e r n of p a t i e n t s o p e r a t e d o n for int e r m i t t e n t c l a u d i c a t i o n is n o t p a t e n c y of the infrai n g u i n a l b y p a s s graft, b u t relief of c l a u d i c a t i o n p a i n , full r e s t o r a t i o n of f u n c t i o n a n d e l i m i n a t i o n of the n e e d for a m p u t a t i o n . This s t u d y s h o w e d that a l m o s t t w o t h i r d s of the s u r v i v i n g p a t i e n t s c o n t i n u e d to b e n e f i t f r o m b o t h the i n i t i a l a n d a d d i t i o n a l v a s c u l a r i n t e r v e n t i o n s for h m b i s c h a e m i a . F u n c t i o n a l success w a s s u s t a i n e d for p e r i o d s e x t e n d i n g o v e r 10-20 years, a n d s u p p o r t s the v i e w that i n f r a i n g u i n a l b y p a s s s u r g e r y for d i s a b l i n g c l a u d i c a t l o n does i n d e e d a p p e a r justified 6,19,41

Conclusion We b e l i e v e that d i s a b l i n g c l a u d i c a t i o n is a v a l i d i n d i c a t i o n for i n f r a i n g u i n a l b y p a s s s u r g e r y i n n o n - d i a betlcs a n d p a t i e n t s w i t h o u t clinical m a r k e r s of cardiac disease. Excellent p a l l i a t i o n of s y m p t o m s c a n b e achieved with bypass surgery with very low operative m o r t a l i t y (<1%), a n d a s u b s e q u e n t a m p u t a t i o n rate less t h a n t h a t a n t i c i p a t e d f r o m the n a t u r a l h i s t o r y of the disease, i.e., 5-year a m p u t a t i o n - r a t e less t h a n 5O/o.42 Patients with comorbid conditions should be informed a b o u t the excess m o r b i d i t y a n d m o r t a l i t y f r o m g e n e r a l i s e d atherosclerosis. W h e n d i s a b l e d b y i n t e r m i t t e n t c l a u d i c a t i o n , h i g h risk p a t i e n t s s h o u l d b e t r e a t e d cons e r v a t i v e l y or b y e n d o v a s c u l a r p r o c e d u r e s i n case of s h o r t - s e g m e n t lesions.

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Eur J Vasc Endovasc Surg Vol 16, October 1998