Renovascular disease in diabetes mellitus: treatment by percutaneous transluminal renal angioplasty

Association between red blood cell distribution width and macrovascular and microvascular complications in diabetes

AIMS/HYPOTHESIS

Red blood cell distribution width (RDW) has been reported to be a risk marker of morbidity and mortality for cardiovascular disease in various study populations. However, no studies have investigated the relationship between RDW and diabetes complications. We therefore evaluated RDW as a marker of macrovascular and microvascular complications in a nationally representative sample of the adult diabetes population in the USA.

METHODS

A cross-sectional study was performed using the nationwide 1988 to 1994 data set from the Third National Health and Nutrition Examination Survey. The association between RDW quartiles and macrovascular and microvascular complications was evaluated in 2,497 non-pregnant adults aged 20 years and older and affected by diabetes. Logistic regression modelling was used to adjust for potential confounding.

RESULTS

Compared with the lowest RDW quartile, higher RDW values (3rd and 4th quartiles) were associated with increased adjusted odds of any vascular complication (OR 4th quartile 2.06 [95% CI 1.11, 3.83]), myocardial infarction (OR 4th quartile 2.45 [95% CI 1.13, 5.28]), heart failure (OR 4th quartile 4.40 [95% CI 1.99, 9.72]), stroke (OR 4th quartile 2.56 [95% CI 1.21, 5.42]) and nephropathy (OR 4th quartile 2.33 [95% CI 1.42, 3.82]). The odds of developing diabetic retinopathy were not significantly increased across RDW quartiles.

CONCLUSIONS/INTERPRETATION

Higher RDW values are associated with increased odds of developing cardiovascular disease and nephropathy in a nationally representative sample of USA adults with diabetes. RDW may be an important clinical marker of vascular complications in diabetes and one that is independent of traditional risk factors and disease duration.

Evaluation and approach to treatment of renal artery stenosis in patients with diabetic nephropathy

Patients with diabetes mellitus are at increased risk for developing peripheral vascular disease and renal artery stenosis (RAS). Furthermore, in diabetic patients the progression of renal atherosclerotic disease toward critical stenosis or occlusion occurs more frequently than in their nondiabetic counterparts. Consequently, clinicians must carry a high level of suspicion for detecting RAS in diabetic patients, particularly those with established coronary and/or peripheral atherosclerotic disease and compromised renal function. In this group of patients early detection of this condition, preferably with a noninvasive diagnostic test, is very important to plan revascularization therapy. In nondiabetic patients, several studies have demonstrated that catheter-based revascularization therapy may arrest or revert renal dysfunction in patients with RAS. Although still the subject of debate, a recent study has shown that in diabetic patients with RAS and impaired renal function, revascularization therapy with endovascular stents has a positive impact in the progression of renal dysfunction.

Use of Endovascular Stents in Atherosclerotic Renovascular Stenosis: Blood Pressure and Renal Function Changes in Hypertensive Patients

Atherosclerotic renal artery stenosis may result in hypertension and ischemic nephropathy. Renal artery endovascular stenting has emerged as current therapy; however, the percentage of patients who benefit from this procedure is still not well established. The authors studied 116 hypertensive patients with atherosclerotic renovascular stenosis who underwent successful renal artery stenting for the first time. At 1 year, there was a significant overall decrease in blood pressure in the group after stenting; however, there was no change in renal function. Also, no significant change in the number of antihypertensive drugs was noted. Blood pressure improved in 55% of the patients, worsened in 14%, and remained unchanged in 31%. Renal function improved in 16% of the patients, worsened in 30%, and remained stable in 54%. In relation to blood pressure control, patients with resistant or difficult-to-control hypertension showed the most improvement in blood pressure control after stenting.

Diabetes mellitus does not preclude stabilization or improvement of renal function after stent revascularization in patients with kidney insufficiency and renal artery stenosis

OBJECTIVE

To assess the impact of stent revascularization on the renal function of diabetic and nondiabetic patients with renal insufficiency.

BACKGROUND

Renal artery revascularization has been shown to stabilize or improve renal function in patients with significant renal artery stenosis and impaired renal function. However, some studies have suggested negligible or no benefit of renal function in diabetic patients with the same condition.

METHODS

We retrospectively compared data from 50 consecutive patients undergoing renal artery stent placement with renal insufficiency (serum creatinine > or = 1.5-4.0 mg/dl) and global ischemia (bilateral or solitary [single] kidney renal artery stenosis) There were 17 diabetic (DM) and 33 nondiabetic (NDM) patients. The endpoints included the follow-up measurements of renal function, blood pressure, and number of antihypertensive medications.

RESULTS

After stent placement, at a mean follow-up of 42 +/- 18 months (range: 6-62 months), 79% NDM (N = 26), and 76% DM patients (N = 13) (P = NS) had improvement in the slope of the reciprocal of creatinine (1/SCr), indicating a beneficial effect in renal function in many patients.

CONCLUSION

Renal artery stent placement appears to be equally beneficial in preserving renal function in DM and NDM patients with ischemic nephropathy and global renal ischemia.

Survival after stenting of severe atherosclerotic ostial renal artery stenoses

PURPOSE

To examine long-term survival after angioplasty and stenting of atherosclerotic renal artery stenosis (RAS).

METHODS

Over a 5-year period, 241 consecutive patients (153 men; mean age 67+/-9 years, range 44-84) were treated with angioplasty and stent implantation for 355 ostial renal stenoses >70%. The procedures were performed in standard fashion using a variety of stents. For survival analysis, the patients were divided into 3 groups based on baseline creatinine levels: group 1: 115 (48%) patients with normal renal function (creatinine <1.2 mg/dL); group 2: 93 (39%) patients with moderately impaired renal function (creatinine 1.2 to 2.5 mg/dL); and group 3: 33 (13%) patients with severely impaired renal function (creatinine >2.5 mg/dL).

RESULTS

All patients were treated successfully without any procedure-related mortality. The 30-day mortality was 0.4% (1/241). Twenty-two patients died during a follow-up of 27+/-15 months (range 1-60) (overall survival 91%). The causes of death were cardiac (congestive heart failure or myocardial infarction, 73%), stroke (13.5%), and malignant disease (13.5%). The survival rate was significantly lower (29.6%) in patients with a baseline serum creatinine >2.5 mg/dL (p<0.0001) than in groups 2 (89.1%) or 1 (95.4%). Long-term survival without hemodialysis or restenosis was 66.6% at 48 months. Independent predictors for a reduced survival were left ventricle function (HR 2.59, 95% CI 1.45 to 4.63, p=0.001 for each 15% incremental decrease), age (HR 1.13, 95% CI 1.03 to 1.25, p=0.011), and baseline renal function (HR 1.58, 95% CI 1.10 to 2.29, p=0.014).

CONCLUSIONS

Survival after successful stenting for severe ostial RAS depends on baseline serum creatinine and left ventricle function. Efforts must be made to avoid the development of advanced ischemic nephropathy and congestive heart failure.

Stent angioplasty of severe atherosclerotic ostial renal artery stenosis in patients with diabetes mellitus and nephrosclerosis

Atherosclerotic renal artery stenosis (ARAS) may lead to deterioration of renal function or hypertension. The clinical outcome after stent angioplasty of ARAS on renal function and blood pressure control in patients with diabetes and nephrosclerosis is the subject of some controversy. We have analyzed the results of our single-center experience with stent angioplasty for severe (>/= 70%) ostial ARAS and present here the results of a subgroup analysis of those patients who had diabetes mellitus and nephrosclerosis. From 1996 to 2001, 241 patients underwent stent angioplasty for the treatment of ARAS at our center. Of these, 99 patients had diabetes mellitus (41%) and 176 patients (73%) had nephrosclerosis defined as intrarenal resistance index (RI) >/= 0.7 diagnosed by duplex ultrasound. All lesions (n = 355) were treated successfully. Mean blood pressure at baseline was comparable and significantly improved immediately after the intervention in all groups (nondiabetics: 102 +/- 12 to 93 +/- 10 mm Hg; diabetics: 102 +/- 14 to 93 +/- 11 mm Hg; RI < 0.7: 105 +/- 13 to 95 +/- 10 mm Hg; RI = 0.7-0.8: 100 +/- 12 to 92 +/- 10 mm Hg; RI > 0.8: 102 +/- 15 to 92 +/- 11 mm Hg; P < 0.0001 each). Baseline serum creatinine was not significantly lower in nondiabetics compared to diabetics (1.46 +/- 0.9 vs. 1.62 +/- 1.2 mg %; P < 0.05) and increased in patients with nephrosclerosis (RI < 0.7: 1.18 +/- 0.6 mg %; RI = 0.7-0.8: 1.57 +/- 1.1 mg %; RI > 0.8: 1.96 +/- 1.6 mg %). Except for patients without nephrosclerosis who had a normal baseline creatinine, serum creatinine decreased significantly in all subgroups during follow-up. Stent angioplasty of ARAS offers favorable acute and long-term clinical results for the preservation of the renal function and for blood pressure control in patients with diabetes mellitus and nephrosclerosis.

The impact of atherosclerotic renovascular disease on diabetic renal failure

Atherosclerotic renovascular disease (ARVD) is common in the general population, and its prevalence increases with age. Parallel studies show it is also common in patients with diabetes. The widespread use of angiotensin converting enzyme inhibitors and angiotensin receptor antagonists for heart and kidney disease might therefore expose arteriopathic diabetic patients to potential harm if they had critical renal artery stenosis. This review looks at the natural history of ARVD in the diabetic and non-diabetic populations: while it is common, it only rarely leads to renal failure. Hence intervention to revascularize ischaemic kidney son the basis of radiological appearances alone may subject some patients to unnecessary therapy. Although untested by randomized trial, a policy of watchful waiting may be the simplest strategy for most diabetic patients with suspected ARVD, reserving angiography and angioplasty (usually backed up by a stent) for those with an abrupt decline in renal function and no other cause for renal deterioration. Future clinical trials may better define subgroups of patients who will truly benefit from renal revascularization.

Combination antihypertensive therapy in the treatment of diabetic nephropathy

Diabetic nephropathy is one of the major causes of end-stage renal disease and is often associated with other macrovascular complications such as ischemic heart disease and peripheral vascular disease. Angiotensin converting enzyme inhibitors (ACE-I) and angiotensin II receptor blockers (AIIR) have both been shown to have a protective effect on the progression of diabetic nephropathy and have thus become the first choice for treatment of hypertension and/or renal involvement in patients with diabetes. However, most of these patients, especially those with type 2 diabetes, require two of more medications in order to reduce their blood pressure to the levels, which have been proposed in recently published consensus papers. These target blood pressure levels are 130/80 mm Hg in diabetic subjects with proteinuria of up to 1 g/day and 125/75 mm Hg in those with proteinuria in excess of 1 g/day. Combinations of different medications may have a synergistic effect. Some of the early studies using a combination of either a nondihydropyridine or a dihydropyridine calcium channel blocker with ACE-I demonstrated a synergistic effect on proteinuria in patients with diabetic nephropathy. However, these studies have not been substantiated, but calcium channel blockers, with their proven ability to reduce blood pressure, play an important role in the treatment of patients with diabetic nephropathy and hypertension. The combination of ACE-I with AIIR may have several theoretical advantages. Many studies using this combination have been performed in animal models of diabetes and in patients with diabetic and nondiabetic renal disease. Some of these studies have demonstrated a synergistic effect of the combination on proteinuria or hypertension, but the results have not been consistent in all studies. It may be concluded that, until additional studies provide more convincing evidence, this combination could be used in patients whose proteinuria or hypertension has not responded to either one of the agents as monotherapy or to a combination of other medications.