Renovascular Disease in Older Adults

Risks for mortality and renal replacement therapy in atherosclerotic renovascular disease compared with other causes of chronic kidney disease

AIM

Patients with atherosclerotic renovascular disease (ARVD) have an increased risk for death and likelihood of initiating renal replacement therapy (RRT) compared with the general population. No data exist to describe prognosis in ARVD compared with other causes of chronic kidney disease (CKD). We compare patient outcomes between ARVD and other causes of CKD.

METHODS

Patients were selected from two prospective observational cohort studies of outcome in ARVD and CKD. Multivariate Cox regression was used to compare risk for RRT and death (both prior to and following initiation of RRT) between patients with ARVD and other causes of CKD.

RESULTS

Of 1472 patients (563 (38%) ARVD, 909 (62%) non-ARVD), 242 (16%) progressed to RRT and 640 (44%) died over a median follow-up period of 4.1 (2.4-5.6) years. Patients with ARVD had an increased risk for death (HR 1.5 (1.2-1.8), P < 0.001) but not for RRT (HR 1.0 (0.7-1.4), P = 0.9). The largest increase in risk for death was observed relative to renal limited diseases, e.g. pyelonephritis (HR 2.4 (1.3-4.5), P = 0.004) and interstitial/infiltrative disease (HR 2.2 (1.3-4.5), P = 0.02). Following initiation of RRT, patients with ARVD had a significantly increased risk for death compared with patients without ARVD (HR 3.3 (2.2-5.0), P < 0.001).

CONCLUSIONS

Patients with ARVD as a cause of CKD have an increased risk for death both prior to and following initiation of RRT. Further work should seek to identify modifiable risk factors relevant to prognosis.

Atherosclerotic renovascular disease in United States patients aged 67 years or older: Risk factors, revascularization, and prognosis

BACKGROUND

Although atherosclerotic renovascular disease is increasingly recognized in chronic kidney disease, few national level studies have examined its clinical epidemiology.

METHODS

Claims data from a 5% random sample of the United States Medicare population were used to select patients without atherosclerotic renovascular disease in the 2 years preceding December 31, 1999 (N= 1,085,250), followed until December 31, 2001.

RESULTS

The incidence of atherosclerotic renovascular disease was 3.7 per 1000 patient-years. Major antecedent associations [P < 0.05, with adjusted hazards ratios (HR) > 1.5] included chronic kidney disease (adjusted HR 2.54), hypertension (2.42), peripheral vascular disease (2.00), and atherosclerotic heart disease (1.70). Adverse event rates after incident atherosclerotic renovascular disease greatly exceeded those in the general population (P < 0.0001): atherosclerotic heart disease, 303.9 per 1000 patient-years (vs. 73.5 in the general population); peripheral vascular disease, 258.6 (vs. 52.2); congestive heart failure, 194.5 (vs. 56.3); cerebrovascular accident or transient ischemic attack, 175.5 (vs. 52.9); death, 166.3 (vs. 63.3); and renal replacement therapy, 28.8 (vs. 1.3). Among atherosclerotic renovascular disease patients, 16.2% underwent a renal revascularization procedure, percutaneously in 96%. Revascularization was not associated with renal replacement therapy, congestive heart failure, or death but was associated with atherosclerotic heart disease (adjusted HR 1.42) (P= 0.004) and peripheral vascular disease (adjusted HR 1.38) (P= 0.002).

CONCLUSION

Atherosclerotic renovascular disease is strongly associated with cardiovascular disease, both past and future. Absolute cardiovascular risk exceeds that of renal replacement therapy. Renal revascularization is used selectively and shows inconsistent associations with cardiovascular outcomes, renal replacement therapy, and death.

Dilemmas in the management of renal artery stenosis

Atherosclerotic renovascular disease (ARVD) accounts for >90% of renal artery stenosis (RAS) in Western populations; the remainder are due to fibromuscular disease (FMD). The epidemiology is quite different in the Indian subcontinent and the Far East where Takayasu's arteritis may be responsible for up to 60% of RAS cases. ARVD is very commonly associated with hypertension and renal dysfunction; it is a disease of ageing and is frequently observed in association with other vascular diseases. There is increasing evidence that in patients with ARVD and chronic renal dysfunction the aetiology of the latter is more often due to long-standing intra-renal vascular disease and parenchymal injury than to reversible ischaemia. This is reflected in the variability in renal functional outcome following revascularization, with an improvement in renal function being observed in only a minority of patients; the majority show no apparent change or even a decline in renal function. A major current challenge concerns the identification of patients who are likely to benefit from renal revascularization procedures, but technological advances in imaging offer potential in aiding this selection. Large-scale randomized controlled trials are required to determine the overall effects of renal artery intervention and, more specifically, to help identify which subgroups of patients will benefit from revascularization.

Spiral laminar flow in the abdominal aorta: a predictor of renal impairment deterioration in patients with renal artery stenosis?

BACKGROUND

Spiral or helical arterial blood flow patterns have been widely observed in both animals and humans. The absence of spiral flow has been associated with carotid arterial disease. The aim of this study was to detect the presence of aortic spiral flow using magnetic resonance imaging (MRI) and to evaluate the relationship of the presence of spiral aortic flow with renal arterial disease and renal function in the follow-up of patients with suspected renal atheromatous disease.

METHODS

Prospective study of 100 patients with suspected renal arterial disease and 44 patient controls. Using a 1.5 T MRI unit (Siemens Symphony), phase contrast flow quantification and three-dimensional contrast enhanced MR angiography of the abdominal aorta were performed. Renal arterial stenoses (RAS) were classified minimal, moderate or severe. Renal function was followed at 3 months before and 6 months after MRI.

RESULTS

Non-spiral flow was more prevalent in patients with more severe RAS. Renal impairment progressed significantly in severe RAS without spiral flow (P = 0.0065), but did not progress significantly in severe RAS with spiral flow (P = 0.12). In minimal or moderate RAS with or without spiral flow there was no significant progression (P = 0.16, 0.13, 0.47, 0.092, respectively).

CONCLUSIONS

Aortic spiral blood flow can be assessed with MRI. Lack of aortic spiral blood flow in patients with severe RAS is associated with significant short-term renal function deterioration. Determination of blood flow patterns may be a useful indicator of renal impairment progression in patients with suspected renal artery stenosis.

Prévalence des sténoses des artères rénales dépistées au cours de coronarographies diagnostiques : dans quels cas doit-on réaliser une aortographie abdominale ?

PURPOSE

To define a subgroup of patients at increased risk of renal artery stenosis (RAS) in a population of patients undergoing cardiac catheterization.

MATERIALS AND METHODS

A total of 467 patients (mean age of 64 Years +/-11) underwent cardiac catheterization and aortography Results were evaluated to detect correlations between the presence or absence of RAS and clinical and biological parameters.

RESULTS

A total of 42 (9%) patients had a renal artery stenosis. Univariate analysis defined parameters correlated with the presence of RAS: systolic blood pressure (p=0.03), pulse pressure (p=0.005), age (p<0.0001), creatinine clearance (p<0.0001), 2-vessel (p=0.028) and 3-vessel (p=0.037) coronary artery diseases. Multivariate analysis showed that the presence of RAS correlated to creatinine clearance (p=0.02) and 2-vessel coronary artery disease. A creatinine clearance between 30 and 60 ml/min and multi-vessel coronary artery disease defined a subgroup at increased risk of RAS with sensitivity, specificity, positive and negative predictive values of: 47.6, 90.1, 32.3 and 94.6%. The prevalence of renal artery stenosis was 5.2% when both parameters were absent.

CONCLUSION

Patients with mild renal insufficiency and multi-vessel coronary artery disease defined a subgroup of patients at increased risk of RAS (32.5%) that may benefit from abdominal aortography performed at the time of cardiac catheterization.

Increasing the diagnostic yield of renal angiography for the diagnosis of atheromatous renovascular disease

Atheromatous renovascular disease (ARVD) is a common cause of hypertension and chronic renal failure (CRF). In this unit, intravenous digital subtraction angiography (DSA) (or intraarterial DSA if indicated) is used as a screening angiographic study when ARVD is suspected. However, increased use of these investigations has resulted in a longer waiting time for angiography. As the majority of studies are negative for ARVD, clinical features and results of investigations of patients undergoing angiography were reviewed to identify those having the greatest likelihood of ARVD. The clinical notes were reviewed for all 249 patients undergoing angiography over an 18-month period. Primary indications for investigation were: hypertension 71 (28.5%), CRF 156 (62.7%) and CRF with severe hypertension 22 (8.8%). 12 of the CRF patients had end-stage renal failure. 166 (66.7%) patients had no evidence of ARVD, while only 83 (33.3%) patients showed some degree of ARVD, 29 (35%) of which had bilateral renal artery disease. There was no significant difference between the ARVD group and the non-ARVD group for mean age (69.0 years vs 63.3 years), male to female ratio, history of smoking (68.7% vs 55.4%), severe hypertension (10.8% vs 9.0%), hypercholesterolaemia (61.4% vs 47.0%), diabetes mellitus (28.6% vs 25.3%) or angiotensin converting enzyme inhibitor-related renal dysfunction (9.6% vs 6.1%). More patients in the ARVD group were investigated for CRF than in the non-ARVD group, as reflected by the higher serum creatinine level and the lower creatinine clearance in the ARVD group. 55 (33.1%) of the non-ARVD patients had no comorbid vascular disease, vascular bruits or ultrasound discrepancy in the size of the two kidneys, whereas all ARVD patients had at least one of these features (negative predictive value 100%). All three features were present in 19.3% of ARVD patients but in only 3.0% of the non-ARVD patients (positive predictive value 76.2%, specificity 97%). We plan to rationalize the criteria for angiography in the light of these findings, anticipating an increase in the diagnostic yield of renal angiography from its current 33.3% to above 42%.

Renovascular hypertension

Approximately 5% of all hypertensive patients have renovascular hypertension, although its true incidence is unknown. The pathophysiology of renovascular hypertension has been linked to other intrarenal systems, the lipoxygenase pathway, and renin angiotensin. Many advances have been made in this field, but emphasis is now being placed on using less invasive or non-invasive tests to identify functionally significant lesions with a high degree of accuracy. The treatment modalities have shifted from aggressive surgical revascularization to less invasive management. The use of arterial stents has simplified the management of patients with renovascular hypertension, but long-term results are not yet available.