The feasibility of catheter-directed thrombolysis for acute deep vein thrombosis: a regional perspective

Background

Deep vein thromboses (DVTs) are a significant cause of morbidity and mortality. Valvular destruction leads to the spectrum of disease called the post-thrombotic syndrome (PTS) with the sequelae of chronic venous ulceration and a reduced quality of life. Catheter-directed thrombolysis (CDT) may reduce the incidence of PTS following an acute proximal DVT and increases quality of life thereafter, but it is uncertain what proportion of patients diagnosed with a DVT would be suitable for CDT.

Methods

This study quantified the proportion of patients investigated for DVT that would have been suitable for CDT. A retrospective review was performed of all upper and lower limb duplex ultrasound scans for suspected DVTs in a contemporary one-year period in a major regional vascular institute. All positive scans for acute proximal lower limb DVTs were compared against strict inclusion and exclusion criteria for CDT, based on national guidelines and international randomized trials.

Results

A total of 2368 duplex ultrasound venous investigations were performed in a one-year period and 252 scans demonstrated DVT. Of these, 158 were acute proximal lower limb DVTs. Application of the inclusion and exclusion criteria for CDT suggested that 47/158 (30%) were potentially suitable for CDT using current criteria. The median age of the 158 patients was 58 years, meaning that more than half were of working age and 54% were men.

Conclusion

Using current eligibility criteria, only about 30% of patients with DVT appear to be suitable for CDT.

Rupture rates of small abdominal aortic aneurysms: a systematic review of the literature

BACKGROUND

Small aneurysms of the abdominal aorta (3.0-5.5 cm in diameter) often are managed by regular surveillance, rather than surgery, because the risk of surgery is considered to outweigh the risk of aneurysm rupture. The risk of small aneurysm rupture is considered to be low. The purpose of this review is to summarise the reported estimates of small aneurysm rupture rates.

METHODS AND FINDINGS

We conducted a systematic review of the literature published before 2010 and identified 54 potentially eligible reports. Detailed review of these studies showed that both ascertainment of rupture, patient follow-up and causes of death were poorly reported: diagnostic criteria for rupture were never reported. There were only 14 studies from which rupture rates (as ruptures per 100 person-years) were available. These 14 published studies included 9779 patients (89% male) over the time period 1976-2006 but only 7 of these studies provided rupture rates specifically for the diameter range 3.0-5.5 cm, which ranged from 0 to 1.61 ruptures per 100 person-years.

CONCLUSIONS

Rupture rates of small abdominal aortic aneurysms would appear to be low, but most studies have been poorly reported and did not have clear ascertainment and diagnostic criteria for aneurysm rupture.

Use of baseline factors to predict complications and reinterventions after endovascular repair of abdominal aortic aneurysm

BACKGROUND

It is uncertain which baseline factors are associated with graft-related complications and reinterventions after endovascular aneurysm repair (EVAR) in patients with a large abdominal aortic aneurysm.

METHODS

Patients randomized to elective EVAR in EVAR Trial 1 or 2 were followed for serious graft-related complications (type 2 endoleaks excluded) and reinterventions. Cox regression analysis was used to investigate whether any prespecified baseline factors were associated with time to first serious complication or reintervention.

RESULTS

A total of 756 patients who had elective EVAR were followed for a mean of 3.7 years, by which time there were 179 serious graft complications (rate 6.5 per 100 person years) and 114 reinterventions (rate 3.8 per 100 person years). The highest rate was during the first 6 months, with an apparent increase again after 2 years. Multivariable analysis indicated that graft-related complications increased significantly with larger initial aneurysm diameter (P < 0.001) and older age (P = 0.040). There was also evidence that patients with larger common iliac diameters experienced higher complication rates (P = 0.011).

CONCLUSION

Graft-related complication and reintervention rates were common after EVAR in patients with a large aneurysm. Younger patients and those with aneurysms closer to the 5.5-cm threshold for intervention experienced lower rates.

Non-Operative or Medical Management of Abdominal Aortic Aneurysm

Non-operative management of patients with abdominal aortic aneurysm (AAA) is required for several different reasons. Since these patients have an increased risk of cardiovascular death therapy to reduce cardiovascular events is essential. Treatment is in line with the medical management of coronary artery disease including smoking cessation, statins and anti-platelet therapy. Some of these therapies also will slow aneurysm growth, which is a target in the management of patients with small AAA. As yet there is no targeted therapy that reduces aneurysm growth, but there is active research in this area. Medical management also is required to reduce peri-operative risks, stabilise endovascular aneurysm repair and minimise the risk of rupture in those with large AAA unfit for aneurysm repair.

Modelling the long-term cost-effectiveness of endovascular or open repair for abdominal aortic aneurysm

Background

Recent randomized trials have shown that endovascular abdominal aortic aneurysm repair (EVAR) has a 3 per cent aneurysm-related survival benefit in patients fit for open surgery, but it also has uncertain long-term outcomes and higher costs. This study assessed the cost-effectiveness of EVAR.

Methods

A decision model was constructed to estimate the lifetime costs and quality-adjusted life years (QALYs) with EVAR and open repair in men aged 74 years. The model includes the risks of death from aneurysm, other cardiovascular and non-cardiovascular causes, secondary reinterventions and non-fatal cardiovascular events. Data were taken largely from the EVAR trial 1 and supplemented from other sources.

Results

Under the base-case (primary) assumptions, EVAR cost £3800 (95 per cent confidence interval (c.i.) £2400 to £5200) more per patient than open repair but produced fewer lifetime QALYs (mean − 0·020 (95 per cent c.i. − 0·189 to 0·165)). These results were sensitive to alternative model assumptions.

Conclusion

EVAR is unlikely to be cost-effective on the basis of existing devices, costs and evidence, but there remains considerable uncertainty.

Medical Management of Abdominal Aortic Aneurysm

Medical management of patients with abdominal aortic aneurysm (AAA) is required for several different reasons. Since these patients have an increased risk of cardiovascular death therapy to reduce cardiovascular events is essential. Treatment is in line with the medical management of coronary artery disease including smoking cessation, statins and anti-platelet therapy. Some of these therapies also will slow aneurysm growth. Currently there is no proven focused therapy that reduces aneurysm growth, but the emerging strategies are discussed. Medical management also is required to reduce peri-operative risks and stabilise endovascular aneurysm repair. Whilst some of the therapies targeting cardiovascular risk reduction may be helpful, other emerging strategies are discussed.

Secondary Interventions and Mortality Following Endovascular Aortic Aneurysm Repair: Device-specific Results from the UK EVAR Trials

OBJECTIVES

To compare secondary intervention rate, aneurysm-related mortality and all-cause mortality for patients receiving elective endovascular aneurysm repair (EVAR) for large abdominal aortic aneurysms with different commercially available endografts.

DESIGN, MATERIALS & METHODS

In the EVAR 1 and 2 multi-centre trials, the principal endografts used were Zenith and Talent and these are compared in 505 patients from EVAR 1 and 143 patients from EVAR 2 followed-up for an average of 3.8 years until 31st December 2005. Outcomes were analysed by Cox proportional hazards regression, with adjustments for potential confounding risk factors and centre. Gore/Excluder graft outcomes also are reported.

RESULTS

Across the two trials the secondary intervention rates were 7.0 and 9.4 per 100 patient years for Zenith and Talent grafts respectively, adjusted hazard ratio 0.77 [95%CI 0.52-1.12]. Aneurysm-related mortality was 1.2 and 1.4 per 100 patient years for Zenith and Talent grafts respectively, adjusted hazard ratio 0.90 [95%CI 0.37-2.19]. All-cause mortality was 8.5 and 10.3 per 100 patient years for Zenith and Talent grafts respectively, adjusted hazard ratio 0.81 [95%CI 0.58-1.14]. The direction of all results was similar when the two trials were analysed separately.

CONCLUSION

There was no significant difference in the performance of the two endografts but the direction of results was slightly in favour of patients with Zenith (versus Talent) endografts.

Simvastatin attenuates the activity of matrix metalloprotease-9 in aneurysmal aortic tissue

To investigate whether statins reduce the concentration of MMP-9 in the aortic wall, we randomised patients undergoing elective open repair of an abdominal aortic aneurysm (AAA) to a pre-operative course of either simvastatin or placebo. MMPs in aortic biopsies were measured using gelatin zymography. Although recruitment closed early because of increasing statin use among eligible patients, with only 21 patients we demonstrated a 40% reduction in MMP-9 levels in the AAA wall in patients randomised to simvastatin. This provides a possible molecular mechanism to explain the reportedly beneficial effects of statins to slow AAA growth.

Patient fitness and survival after abdominal aortic aneurysm repair in patients from the UK EVAR trials

Background

The aim was to use a validated fitness score to determine whether fitter patients with a large abdominal aortic aneurysm (AAA) benefited from having open rather than endovascular repair.

Methods

The Customized Probability Index (CPI) was applied to patients in the Endovascular Aneurysm Repair (EVAR) I and II trials. Interaction tests between CPI and randomized group assessed the effect of fitness and type of AAA repair on elective 30-day mortality and 4-year survival.

Results

The mean(s.d.) CPI scores were 3·6(9·3) for 1252 EVAR I patients and 10·0(11·3) for 404 EVAR II patients (range − 25 to + 43) (P &lt; 0·001). The fitness of EVAR I patients was classified as good (579 patients, mean CPI − 4·2), moderate (331 patients, mean CPI 5·7) or poor (338 patients, mean CPI 15·1). Only in the good fitness group did 30-day mortality convincingly favour endovascular repair (odds ratio 0·24, P = 0·030), but overall the test of interaction was not significant (P = 0·363). For 4-year all-cause and aneurysm-related mortality, there was no benefit for either treatment across all fitness scores (P = 0·281 and P = 0·371 respectively).

Conclusion

The benefit of endovascular repair was most convincing in the fittest patients. There was no evidence that the fittest patients benefited more from open surgery.

Final 12-year follow-up of Surgery versus Surveillance in the UK Small Aneurysm Trial

Background

The aim was to determine whether early open surgical repair would benefit patients with small abdominal aortic aneurysm compared with surveillance on long-term follow-up.

Methods

The 1090 patients who were enrolled into the UK Small Aneurysm Trial between 1991 and 1995 were followed up for aneurysm repair and mortality until November 2005.

Results

By November 2005, 714 patients (65·5 per cent) had died, 929 (85·2 per cent) had undergone aneurysm repair, 150 (13·8 per cent) had died without aneurysm repair and 11 (1·0 per cent) remained alive without aneurysm repair. After 12 years, mortality in the surgery and surveillance groups was 63·9 and 67·3 per cent respectively, unadjusted hazard ratio 0·90 (P = 0·139). Three-quarters of the surveillance group eventually had aneurysm repair, with a 30-day elective mortality of 6·3 per cent (versus 5·0 per cent in the early surgery group, P = 0·366). Estimates suggested that the cost of treatment was 17 per cent higher in the early surgery group, with a mean difference of £1326. The death rate in these patients was about twice that in the population matched for age and sex.

Conclusion

There was no long-term survival benefit of early elective open repair of small abdominal aortic aneurysms. Even after successful aneurysm repair, the mortality among these patients was higher than in the general population.

Genes predisposing to rapid aneurysm growth

The aim of the study was to investigate the effect of functional polymorphisms in promoters of the MMP-2 (-1306 C > T), MMP-3 (-1171 5A > 6A), MMP-9 (-1562 C > T), MMP-12 (-82 A > G), TIMP-1 (-372 C > T), and PAI-1 (-675 4G > 5G and -847 A > G) genes on the growth rate of small abdominal aortic aneurysms. The patients with small aneurysms were recruited from the surveillance arm of the U.K. Small Aneurysm Trial and monitored for aneurysm growth, mean follow-up 2.6 years. Mean linear aneurysm growth rates were calculated by flexible modeling. For MMP-2, MMP-3, MMP-9, MMP-12, and TIMP-1 polymorphisms there were no clear associations with aneurysm growth. The increased growth rates for patients of 5G5G PAI-1 genotype were of borderline significance (P = 0.06). However, PAI-1 haplotype analysis showed that 5G5G/GG patients had significantly faster aneurysm growth (mean 0.46 mm/year faster). There was no evidence that any specific MMP polymorphism had a clinically significant effect on aneurysm growth. However the plasminogen system (via PAI-1) appears to have a small, but clinically significant, role in aneurysm growth.

Influence of fibrillin-1 genotype on the aortic stiffness in men

Aortic stiffness is a predictor of cardiovascular mortality. The mechanical properties of the arterial wall depend on the connective tissue framework, with variation in fibrillin-1 and collagen I genes being associated with aortic stiffness and/or pulse pressure elevation. The aim of this study was to investigate whether variation in fibrillin-1 genotype was associated with aortic stiffness in men. The mechanical properties of the abdominal aorta of 79 healthy men (range 28–81 yr) were investigated by ultrasonographic phase-locked echo tracking. Fibrillin-1 genotype, characterized by the variable tandem repeat in intron 28, and collagen type I alpha 1 genotype characterized by the 2,064 G>T polymorphism, were determined by using DNA from peripheral blood cells. Three common fibrillin-1 genotypes, 2-2, 2-3, and 2-4, were observed in 50 (64%), 10 (13%), and 11 (14%) of the men, respectively. Those of 2-3 genotype had higher pressure strain elastic modulus and aortic stiffness compared with men of 2-2 or 2-4 genotype ( P = 0.005). Pulse pressure also was increased in the 2-3 genotype ( P = 0.04). There was no significant association between type 1 collagen genotype and aortic stiffness in this cohort. In conclusion, the fibrillin-1 2-3 genotype in men was associated with increased aortic stiffness and pulse pressure, indicative of an increased risk for cardiovascular disease.

Genotype–phenotype relationships in an investigation of the role of proteases in abdominal aortic aneurysm expansion

Background

The aim of the study was to investigate the effect of functional polymorphisms in promoters of matrix metalloproteinase (MMP) 2, MMP-3, MMP-9, MMP-12 and plasminogen activator inhibitor (PAI) 1 genes on the growth rate of small abdominal aortic aneurysms (AAA).

Methods

Some 455 individuals with a small AAA (4·0–5·5 cm) were monitored for aneurysm growth by ultrasonography (mean follow-up 2·6 years). They also provided a DNA sample for analysis of the −1306 C &gt; T, −1171 5A &gt; 6A, −1562 C &gt; T, −82 A &gt; G and −675 4G &gt; 5G alleles of MMP-2, MMP-3, MMP-9, MMP-12 and PAI-1, respectively. Mean linear AAA growth rates were calculated by flexible modelling; the sample size was sufficient to detect variants that influenced the growth rate by 25 per cent.

Results

For MMP-2, MMP-9 and MMP-12 genotypes, growth rates were similar to the mean linear growth rate of 3·08 mm per year. For MMP-3, growth rates were 3·05 (for 5A5A), 3·19 (for 5A6A) and 2·90 (for 6A6A) mm per year. For PAI-1, patients with 4G4G, 4G5G and 5G5G genotypes had growth rates of 3·18, 2·92 and 3·47 mm per year, respectively, for aneurysms with a baseline diameter of 45·1, 44·6 and 46·2 mm. The increased growth rate for patients with PAI-1 5G5G genotype was not statistically significant (P = 0·061), although these patients had the lowest plasma PAI-1 concentrations (P = 0·018).

Conclusion

There was no evidence that any specific MMP polymorphism had a clinically significant effect on AAA expansion. The plasminogen system may have a small but clinically significant role in AAA development. Much larger studies would be needed to evaluate genes of smaller effect.

Perioperative β-blockade (Pobble) for patients undergoing infrarenal vascular surgery: Results of a randomized double-blind controlled trial

OBJECTIVE

To assess whether a pragmatic policy of perioperative beta-blockade, with metoprolol, reduced the 30-day cardiovascular morbidity and mortality and reduced the length of hospital stay in average patients undergoing infrarenal vascular surgery.

METHODS

This was a double-blind randomized placebo-controlled trial that occurred in vascular surgical units in four UK hospitals. Participants were 103 patients without previous myocardial infarction who had infrarenal vascular surgery between July 2001 and March 2004. Interventions were oral metoprolol (50 mg twice daily, supplemented by intravenous doses when necessary) or placebo from admission until 7 days after surgery. Holter monitors were kept in place for 72 hours after surgery.

RESULTS

Eighty men and 23 women (median age, 73 years) were randomized, 55 to metoprolol and 48 to placebo, and 97 (94%) underwent surgery during the trial. The most common operations were aortic aneurysm repair (38%) and distal bypass (29%). Intraoperative inotropic support was required in 64% and 92% of patients in the placebo and metoprolol groups, respectively. Within 30 days, cardiovascular events occurred in 32 patients, including myocardial infarction (8%), unstable angina (9%), ventricular tachycardia (19%), and stroke (1%). Four (4%) deaths were reported. Cardiovascular events occurred in 15 (34%) and 17 (32%) patients in the placebo and metoprolol groups, respectively (unadjusted relative risk, 0.94; 95% confidence interval, 0.53-1.66; adjusted [for age, sex, statin use, and aortic cross-clamping] relative risk, 0.87; 95% confidence interval, 0.48-1.55). Time from operation to discharge was reduced from a median of 12 days (95% confidence interval, 9-19 days) in the placebo group to 10 days (95% confidence interval, 8-12 days) in the metoprolol group (adjusted hazard ratio, 1.71; 95% confidence interval, 1.09-2.66; P < .02).

CONCLUSIONS

Myocardial ischemia was evident in a high proportion (one third) of the patients after surgery. A pragmatic regimen of perioperative beta-blockade with metoprolol did not seem to reduce 30-day cardiovascular events, but it did decrease the time from surgery to discharge.

Vitamin D, Shedding Light on the Development of Disease in Peripheral Arteries

Vitamin D is generally associated with calcium metabolism, especially in the context of uptake in the intestine and the formation and maintenance of bone. However, vitamin D influences a wide range of metabolic systems through both genomic and nongenomic pathways that have an impact on the properties of peripheral arteries. The genomic effects have wide importance for angiogenesis, elastogenesis, and immunomodulation; the nongenomic effects have mainly been observed in the presence of hypertension. Although some vitamin D is essential for cardiovascular health, excess may have detrimental effects, particularly on elastogenesis and inflammation of the arterial wall. Vitamin D is likely to have a role in the paradoxical association between arterial calcification and osteoporosis. This review explores the relationship between vitamin D and a range of physiological and pathological processes relevant to peripheral arteries.

Comparison of endovascular aneurysm repair with open repair in patients with abdominal aortic aneurysm (EVAR trial 1), 30-day operative mortality results: randomised controlled trial

BACKGROUND

Endovascular aneurysm repair (EVAR) is a new technology to treat patients with abdominal aortic aneurysm (AAA) when the anatomy is suitable. Uncertainty exists about how endovascular repair compares with conventional open surgery. EVAR trial 1 was instigated to compare these treatments in patients judged fit for open AAA repair.

METHODS

Between 1999 and 2003, 1082 elective (non-emergency) patients were randomised to receive either EVAR (n=543) or open AAA repair (n=539). Patients aged at least 60 years with aneurysms of diameter 5.5 cm or more, who were fit enough for open surgical repair (anaesthetically and medically well enough for the procedure), were recruited for the study at 41 British hospitals proficient in the EVAR technique. The primary outcome measure is all-cause mortality and these results will be released in 2005. The primary analysis presented here is operative mortality by intention to treat and a secondary analysis was done in per-protocol patients.

FINDINGS

Patients (983 men, 99 women) had a mean age of 74 years (SD 6) and mean AAA diameter of 6.5 cm (SD 1). 1047 (97%) patients underwent AAA repair and 1008 (93%) received their allocated treatment. 30-day mortality in the EVAR group was 1.7% (9/531) versus 4.7% (24/516) in the open repair group (odds ratio 0.35 [95% CI 0.16-0.77], p=0.009). By per-protocol analysis, 30-day mortality for EVAR was 1.6% (8/512) versus 4.6% (23/496) for open repair (0.33 [0.15-0.74], p=0.007). Secondary interventions were more common in patients allocated EVAR (9.8% vs 5.8%, p=0.02).

INTERPRETATION

In patients with large AAAs, treatment by EVAR reduced the 30-day operative mortality by two-thirds compared with open repair. Any change in clinical practice should await durability and longer term results.