Validation of the Finnvasc Score in Infrainguinal Percutaneous Transluminal Angioplasty for Critical Lower Limb Ischemia
Article Outline
The aim of the present study was to validate the Finnvasc score for prediction of immediate outcome after infrainguinal percutaneous transluminal angioplasty (PTA) for critical lower limb ischemia (CLI). Our registry included prospective data on 512 patients who underwent isolated infrainguinal PTA revascularization procedures for CLI. The Finnvasc score herein evaluated was calculated by assigning one point each to diabetes, coronary artery disease, foot gangrene, and urgent operation. Early mortality and major limb amputation rates after PTA revascularization were 2.5% and 12.3%, respectively. Seventy-two patients (14.1%) died and/or had lower limb amputation. Diabetes (p = 0.001), foot gangrene (p = 0.047), urgent operation (p < 0.0001), and preoperative renal failure (p = 0.001) were independent predictors of postoperative mortality and/or major limb amputation. Finnvasc score was predictive of major lower limb amputation (p = 0.003), mortality (p < 0.0001), and mortality and/or major amputation (p < 0.0001) after PTA. Mortality, major lower limb amputation, and combined end point rates in patients with a Finnvasc score of 3-4 were 12.8%, 25.6%, and 35.9%, respectively. The Finnvasc score is a simple risk scoring method which can be useful to estimate the risk of immediate postprocedural mortality and/or major lower limb amputation also in patients undergoing infrainguinal PTA for CLI.
Introduction
Critical leg ischemia (CLI) is a life quality–impairing disease that constitutes an important burden for vascular units.1 Although there is controversy over whether surgical or endovascular repair is the most appropriate therapy,2 there is growing enthusiasm in employing the latter as a primary approach.3, 4, 5, 6 Percutaneous transluminal angioplasty (PTA) is considered a minimally invasive procedure, but still early mortality and major amputation rates range widely from 0% to 4%2, 7, 8 and from 3% to 21%, respectively.2, 6, 7, 8 This suggests that there is a need for a scoring method for stratification of the operative risk in this patient population. Herein, we have evaluated a recently developed score for prediction of outcome after infrainguinal surgical revascularization for CLI9 in patients who underwent infrainguinal PTA.
Materials and Methods
Data from 512 infrainguinal PTA procedures performed for CLI from 1991 to 1997 at our institution were prospectively collected. Definition criteria for preoperative, operative, and procedural variables were defined according to the Finnvasc criteria.10 Details on Finnvasc Registry criteria have been described previously.10 CLI was defined as Fontaine III and IV stage disease. A number of risk factors were included in this analysis: coronary artery disease (myocardial infarction and/or ongoing angina or previous coronary artery bypass surgery), cerebrovascular disease (stroke and/or transient ischemic attacks), renal disease (history of chronic or acute renal failure or serum creatinine concentration >150 μmol/L), diabetes (hyperglycemia requiring dietary control, oral medication, or insulin therapy), hypertension (medication for hypertension or arterial blood pressure >165/95 mm Hg), pulmonary disease (asthma or chronic obstructive pulmonary disease), history of arterial surgical and/or endovascular revascularization or lower limb amputation, primary or secondary procedure, and elective or urgent operation procedure. Hyperlipidemia and smoking habit were not included in the present analysis as the former is likely to be unreported because of lack of routine evaluation of serum cholesterol and triglycerides and information on smoking habit obtained from patients is unreliable.11
We included in this study only patients who underwent a PTA on a single side. In three of these patients, a PTA procedure on the iliac artery was associated with infrainguinal PTA.
The Finnvasc score herein evaluated was calculated by assigning one point each to diabetes, coronary artery disease, foot gangrene, and urgent operation.9
Statistical analysis was performed using SPSS statistical software (v. 14.0.1; SPSS, Inc., Chicago, IL). Pearson's chi-squared test, Fisher's exact test, and the Mann-Whitney test were used for univariate analysis. Logistic regression with the help of backward selection was used for multivariate analysis. Only preoperative variables with p < 0.05 at univariate analysis were included in the regression model. The receiver operating characteristic (ROC) curve was used to estimate the predictive value of this risk scoring method. p < 0.05 was considered statistically significant.
Results
During a mean follow-up period of 31 ± 30 days, 13 patients (2.5%) died, 63 patients (12.3%) had lower limb amputation, and 72 patients (14.1%) died and/or had major lower limb amputation. Table I summarizes the clinical data and their distribution according to the major postprocedural outcome end points in the overall series. Postprocedural complications are reported in Table II.
Table I. Clinical and operative risk factors and their relationship with 30-day outcome after infrainguinal endovascular revascularization in the overall series
| Overall | Death | Major lower limb amputation | Death and/or major lower limb amputation | |
|---|---|---|---|---|
| Age (years) | 72.5 ± 10.8 | |||
| Adverse outcome | 68.8 ± 9.8 | 70.1 ± 12.2 | 70.1 ± 11.7 | |
| No adverse outcome | 72.6 ± 10.8 | 72.8 ± 10.6 | 72.9 ± 10.6 | |
| Gender | ||||
 Female | 325 (63.5) | 9 (2.8) | 39 (12.0) | 45 (13.8) |
| Male | 187 (36.5) | 4 (2.1) | 24 (12.8) | 27 (14.4) |
| Diabetes | ||||
| Absent | 153 (29.9) | 1 (0.7) | 8 (5.2)∗∗ | 8 (5.2)∗∗ |
| Present | 359 (70.1) | 12 (3.3) | 55 (15.3) | 64 (17.8) |
| Hypertension | ||||
| Absent | 320 (62.5) | 9 (2.8) | 40 (12.5) | 45 (14.1) |
| Present | 192 (37.5) | 4 (2.1) | 23 (12.0) | 27 (14.1) |
| Coronary artery disease | ||||
| Absent | 226 (44.1) | 5 (2.2) | 31 (13.7) | 33 (14.6) |
| Present | 286 (55.9) | 8 (2.8) | 32 (11.2) | 39 (13.6) |
| Cerebrovascular disease | ||||
| Absent | 414 (80.9) | 12 (2.9) | 55 (13.3) | 63 (15.2) |
| Present | 98 (19.1) | 1 (1.0) | 8 (8.2) | 9 (9.2) |
| Pulmonary disease | ||||
| Absent | 479 (93.6) | 12 (2.5) | 61 (12.7) | 69 (14.4) |
| Present | 33 (6.4) | 1 (3.0) | 2 (6.1) | 3 (9.1) |
| Renal failure | ||||
| Absent | 430 (84.0) | 6 (1.4)∗∗ | 45 (10.5)∗∗ | 51 (11.9)∗∗ |
| Present | 82 (16.0) | 7 (8.5) | 18 (22.0) | 21 (25.6) |
| Previous vascular surgery or amputation | ||||
| Absent | 303 (59.2) | 6 (2.0) | 29 (9.6)∗ | 33 (10.9) |
| Present | 209 (40.8) | 7 (3.3) | 34 (16.3) | 39 (18.7) |
| Indication | ||||
| Rest pain | 88 (17.2) | 3 (3.4) | 8 (9.1) | 10 (11.4) |
| Ulcer | 384 (75.0) | 9 (2.3) | 46 (12.0) | 52 (13.5) |
| Gangrene | 40 (7.8) | 1 (2.5) | 9 (22.5)a | 10 (25.0)a |
| Level of PTA | ||||
| No infrapopliteal | 282 (55.1) | 7 (2.5) | 31 (11.0) | 37 (13.1) |
| Infrapopliteal | 230 (44.9) | 6 (2.6) | 32 (13.9) | 35 (15.2) |
| Urgent operation | ||||
| Absent | 452 (88.3) | 7 (1.5)∗∗ | 49 (10.8)∗ | 53 (11.7)∗∗∗ |
| Present | 60 (11.7) | 6 (10.0) | 14 (23.3) | 19 (31.7) |
aGangrene versus rest pain or ulcer. |
∗p < 0.05. |
∗∗p < 0.01. |
∗∗∗p < 0.0001. |
Table II. Complications immediately after infrainguinal PTA for CLI
| n (%) | |
|---|---|
| Death | 13 (2.5) |
| Major lower limb amputation | 63 (12.3) |
| Superficial wound infection | 2 (0.4) |
| Hematoma | 10 (2.0) |
| Seroma | 1 (0.2) |
| Cardiac complications | 25 (4.9) |
| Respiratory complications | 8 (1.6) |
| Renal complications | 5 (1.0) |
| Sepsis | 7 (1.4) |
| Deep vein thrombosis | 2 (0.4) |
| Multiorgan failure | 1 (0.2) |
| Intensive care unit stay >5 days | 2 (0.4) |
In 16 patients PTA was attempted without success. Twenty patients (3.9%) underwent one or more vascular and/or endovascular reinterventions immediately after PTA. There were eight PTAs, four thromboembolectomies, three infrapopliteal bypasses, two femoropopliteal bypasses, two thrombolyses, and four arteriorrhaphies. These patients had a higher risk of immediate postprocedural death and/or major amputation (35.0% vs. 13.2%, p = 0.014) and tended to have significantly higher risks of death (10.0% vs. 2.2%, p = 0.087) and major amputation (25.0% vs. 11.8%, p = 0.086) after PTA.
Overall, PTA failures, accounted as failed attempts plus those requiring any further revascularization procedure, occurred in 31 cases (6.1%). These failures were associated with an increased risk of postprocedural death and/or major amputation (32.3% vs. 12.9%, p = 0.006) and risk of death (9.7% vs. 2.1%, p = 0.038) and tended to have a higher risk for major amputation (22.6% vs. 11.6%, p = 0.087) after PTA.
The Finnvasc score was predictive of these outcome end points (Fig. 1). The rates of lower limb amputation and/or death after PTA according to the Finnvasc score are shown in Figure 1.
Fig. 1
Figure showing the incidence of adverse outcome after infrainguinal PTA for CLI. Since only six patients had a score of 4, a group of patients with a score of 3-4 is herein depicted.
Preoperative renal failure was found to be a significant predictor of adverse outcome in this series, and it maintained its significance at multivariate analysis along with diabetes, urgent operation, and gangrene (Table III). Three of four variables included in the Finnvasc score were found to be independent predictors of immediate major lower limb amputation and/or death after PTA.
Table III. Independent predictors of death and/or major amputation after infrainguinal PTA for CLI
| Risk factors | |
|---|---|
| Renal failure | p = 0.001, OR = 2.74, 95% CI 1.50-5.02 |
| Diabetes | p = 0.001, OR = 3.67, 95% CI 1.69-7.97 |
| Urgent operation | p < 0.0001, OR = 3.66, 95% CI 1.91-7.01 |
| Gangrene | p = 0.047, OR = 2.24, 95% CI 1.01-4.96 |
The mean Finnvasc score was 1.5 ± 0.8. The area under the ROC curve for the Finnvasc score in predicting postprocedural major lower limb amputation and/or death was 0.64 (95% confidence interval [CI] 0.57-0.71). This did not improve markedly when renal failure was added to the original score (0.67, 95% CI 0.61-0.73). The area under the curve for major lower limb amputation was 0.61 (95% CI 0.53-0.68) and that for death was 0.70 (95% CI 0.54-0.87) for the original Finnvasc score, and they were 0.64 (95% CI 0.57-0.70) and 0.79 (95% CI 0.67-0.90), respectively, for the modified score including renal failure.
Discussion
Despite its minimally invasive nature, PTA is associated with a certain risk of immediate postprocedural mortality or limb loss.6 This emphasizes the need of a careful assessment of the preoperative status of the patient and the need of a method that reliably predicts postprocedural outcome. The risk-scoring system herein evaluated provides an easy and rather reliable estimate of immediate outcome by using just a few preoperative risk factors that are easy to retrieve. By assigning one point to each risk factor, such as diabetes, coronary artery disease, urgent operation, and gangrene, it is possible to identify those patients at high risk of morbidity and mortality after revascularization. Coronary artery disease did not prove to be an independent predictor of operative outcome in patients treated with PTA as it was in the infrainguinal surgical revascularization series,9 most likely due to the more invasive nature of surgical revascularization.
PTA is considered a good option to treat patients precluded from open surgery because of poor health status,5, 12 but it has its own limitations as herein shown by the poor outcome of a few patients. Indeed, patients with a Finnvasc score of 3-4 have a risk of immediate death and/or major lower limb amputation of about 36% after PTA. Furthermore, this revascularization method seems to be associated with poor outcome also in patients with preoperative renal failure. Indeed, renal failure is a major determinant of poor outcome in all cardiovascular procedures, particularly in patients with CLI.13, 14, 15
Taylor et al.16 recently suggested that primary limb amputation could be a better treatment for selected patients with CLI who are unfit for surgical revascularization. Moreover, a successful attempt at PTA may occur without any significant daily-life improvement of a patient in poor general condition.14 In this sense, clinical application of the Finnvasc score may identify about 7% of patients in whom primary amputation would be a better treatment method.
Unfortunately, our study is based on an old series of CLI patients undergoing infrainguinal PTA and, moreover, the Finnvasc score does not include the preoperative angiographic findings, the latter having a major impact on the technical success of PTA and the outcome. On the other hand, data were collected on a prospective basis, and it is worth noting that this study constitutes a first attempt to validate a risk score in CLI patients undergoing infrainguinal revascularization with PTA. A simple scoring method easy to use by the clinician at the bedside is an important tool in therapeutic decision making as well as informing the patient about the risk of limb loss or death after the procedure. We believe that evaluation of the Finnvasc score in other vascular centers on both short- and long-term outcome may contribute to its validation and possibly to modifications that may enhance its accuracy.
In conclusion, the Finnvasc score is predictive of the immediate outcome after infrainguinal PTA for CLI. This study has shown that development of a risk scoring method in this patient population is possible, and eventual improvements of the Finnvasc score may further enhance its scientific and clinical value.
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PII: S0890-5096(08)00075-7
doi:10.1016/j.avsg.2008.01.007
© 2008 Annals of Vascular Surgery Inc. Published by Elsevier Inc All rights reserved.
