Tyrone J. Collins

Nitinol Stent Implantation Versus Balloon Angioplasty for Lesions in the Superficial Femoral Artery and Proximal Popliteal Artery Twelve-Month Results From the RESILIENT Randomized Trial

Background—Controversy still exists regarding the best endovascular treatment strategy for patients with symptomatic disease of the superficial femoral artery. There are conflicting data regarding the benefits of superficial femoral artery stenting and the role of primary stenting compared with balloon angioplasty with provisional stent implantation. Methods and Results—A total of 206 patients from 24 centers in the United States and Europe with obstructive lesions of the superficial femoral artery and proximal popliteal artery and intermittent claudication were randomized to implantation of nitinol stents or percutaneous transluminal angioplasty. The mean total lesion length was 71 mm for the stent group and 64 mm for the angioplasty group. Acute lesion success (<30% residual stenosis) was superior for the stent group compared with the angioplasty group (95.8% versus 83.9%; P<0.01). Twenty-nine (40.3%) patients in the angioplasty group underwent bailout stenting because of a suboptimal angiographic result or flow-limiting dissection. Bailout stenting was treated as a target lesion revascularization and loss of primary patency in the final analysis. At 12 months, freedom from target lesion revascularization was 87.3% for the stent group compared with 45.1% for the angioplasty group (P<0.0001). Duplex ultrasound-derived primary patency at 12 months was better for the stent group (81.3% versus 36.7%; P<0.0001). Through 12 months, fractures occurred in 3.1% of stents implanted. No stent fractures resulted in loss of patency or target lesion revascularization. Conclusions—In this multicenter trial, primary implantation of a self-expanding nitinol stent for moderate-length lesions in the superficial femoral artery and proximal popliteal artery was associated with better acute angiographic results and improved patency compared with balloon angioplasty alone. Clinical Trial Registration—URL: http://www.clinicaltrials.gov. Unique identifier: NCT00673985.

Nitinol Stent Implantation Versus Balloon Angioplasty for Lesions in the Superficial Femoral Artery and Proximal Popliteal ArteryClinical Perspective

Background—Controversy still exists regarding the best endovascular treatment strategy for patients with symptomatic disease of the superficial femoral artery. There are conflicting data regarding the benefits of superficial femoral artery stenting and the role of primary stenting compared with balloon angioplasty with provisional stent implantation. Methods and Results—A total of 206 patients from 24 centers in the United States and Europe with obstructive lesions of the superficial femoral artery and proximal popliteal artery and intermittent claudication were randomized to implantation of nitinol stents or percutaneous transluminal angioplasty. The mean total lesion length was 71 mm for the stent group and 64 mm for the angioplasty group. Acute lesion success (<30% residual stenosis) was superior for the stent group compared with the angioplasty group (95.8% versus 83.9%; P<0.01). Twenty-nine (40.3%) patients in the angioplasty group underwent bailout stenting because of a suboptimal angiographic result or flow-limiting dissection. Bailout stenting was treated as a target lesion revascularization and loss of primary patency in the final analysis. At 12 months, freedom from target lesion revascularization was 87.3% for the stent group compared with 45.1% for the angioplasty group (P<0.0001). Duplex ultrasound-derived primary patency at 12 months was better for the stent group (81.3% versus 36.7%; P<0.0001). Through 12 months, fractures occurred in 3.1% of stents implanted. No stent fractures resulted in loss of patency or target lesion revascularization. Conclusions—In this multicenter trial, primary implantation of a self-expanding nitinol stent for moderate-length lesions in the superficial femoral artery and proximal popliteal artery was associated with better acute angiographic results and improved patency compared with balloon angioplasty alone. Clinical Trial Registration—URL: http://www.clinicaltrials.gov. Unique identifier: NCT00673985.

Unstable Angina A Comparison of Angioscopic Findings Between Diabetic and Nondiabetic Patients

BACKGROUND Patients with diabetes mellitus have a higher prevalence of atherosclerotic heart disease and a higher incidence of myocardial infarction than the general population. Diabetic patients also have several hematologic, rheologic, and metabolic abnormalities not present in their nondiabetic counterparts that may predispose them to atherosclerotic plaque rupture and intraluminal thrombosis and consequently may lead to the formation of morphologically complex plaques and the development of acute coronary syndromes. METHODS AND RESULTS Percutaneous coronary angioscopy was performed in 55 consecutive patients with unstable angina. We observed plaque color, texture, and the incidence of intracoronary thrombus associated with the culprit lesions of these patients. The population consisted of 17 (31%) diabetic and 38 (69%) nondiabetic patients. The presence of coronary risk factors was not significantly different between the two populations. Ulcerated plaque was found in 16 of 17 (94%) diabetic patients versus 23 of 38 (60%) nondiabetic patients (P = .01). Intracoronary thrombi were seen in 16 of 17 (94%) diabetic patients versus 21 of 38 (55%) nondiabetic patients (P = .004). CONCLUSIONS The results of the angioscopic examination show that diabetic patients with unstable angina have a higher incidence of plaque ulceration and intracoronary thrombus formation than nondiabetic patients. This increased frequency of complex lesion morphology is consistent with the disproportionately higher risk for development of acute coronary syndromes in these patients.

Renal Artery Stent Placement: Utility in Lesions Difficult to Treat With Balloon Angioplasty

OBJECTIVES We assessed the safety and efficacy of stent placement in patients with poorly controlled hypertension and renal artery stenoses, which are difficult to treat with balloon angioplasty alone. BACKGROUND Preliminary experience with stent placement suggests improved results over balloon angioplasty alone in patients with atherosclerotic renal artery stenosis. METHODS Balloon-expandable stents were placed in 100 consecutive patients (133 renal arteries) with hypertension and renal artery stenosis. Sixty-seven of the patients had unilateral renal artery stenosis treated and 33 had bilateral renal artery stenoses treated with stents placed in both renal arteries. RESULTS Angiographic success, as determined by quantitative angiography, was obtained in 132 (99%) of 133 lesions. Early clinical success was achieved in 76% of the patients. Six months after stent placement, the systolic blood pressure was reduced from 173 +/- 25 to 147 +/- 23 mm Hg (p < 0.001); the diastolic pressure from 88 +/- 17 to 76 +/- 12 mm Hg (p < 0.001); and the mean number of antihypertensive medications per patient from 2.6 +/- 1 to 2.0 +/- 0.9 (p < 0.001). Angiographic follow-up at a mean of 8.7 +/- 5.0 months in 67 patients revealed restenosis (>50% diameter narrowing) in 15 (19%) of 80 stented vessels. CONCLUSIONS Renal artery stenting is an effective treatment for renovascular hypertension, with a low angiographic restenosis rate. Stent placement appears to be a very attractive therapy in patients with lesions difficult to treat with balloon angioplasty such as renal aorto-ostial lesions and restenotic lesions, as well as after a suboptimal balloon angioplasty result.

Coronary Thrombi Increase PTCA Risk Angioscopy as a Clinical Tool

BACKGROUND The presence of angiographically identified intracoronary thrombus has been variably associated with complications after coronary angioplasty. Angiography has been shown to be less sensitive than angioscopy for detecting subtle details of intracoronary morphology, such as intracoronary thrombi. The clinical importance of thrombi detectable by angioscopy but not by angiography is not known. METHODS AND RESULTS Percutaneous coronary angioscopy was performed in 122 patients undergoing conventional coronary balloon angioplasty (PTCA) at six medical centers. Unstable angina was present in 95 patients (78%) and stable angina in 27 (22%). Therapy was not guided by angioscopic findings, and no patient received thrombolytic therapy as an adjunct to angioplasty. Coronary thrombi were identified in 74 target lesions (61%) by angioscopy versus only 24 (20%) by angiography. A major in-hospital complication (death, myocardial infarction, or emergency bypass surgery) occurred in 10 of 74 patients (14%) with angioscopic intracoronary thrombus, compared with only 1 of 48 patients (2%) without thrombi (P = .03). In-hospital recurrent ischemia (recurrent angina, repeat PTCA, or abrupt occlusion) occurred in 19 of 74 patients (26%) with angioscopic intracoronary thrombi versus only 5 of 48 (10%) without thrombi (P = .03). Relative risk analysis demonstrated that angioscopic thrombus was strongly associated with adverse outcomes (either a major complication or a recurrent ischemic event) after PTCA (relative risk, 3.11; 95% CI, 1.28 to 7.60; P = .01) and that angiographic thrombi were not associated with these complications (relative risk, 0.85; 95% CI, 0.36 to 2.00; P = .91). CONCLUSIONS The presence of intracoronary thrombus associated with coronary stenoses is significantly underestimated by angiography. Angioscopic intracoronary thrombi, the majority of which were not detected by angiography, are associated with an increased incidence of adverse outcomes after coronary angioplasty.

Nitinol Stent Implantation vs. Balloon Angioplasty for Lesions in the Superficial Femoral and Proximal Popliteal Arteries of Patients With Claudication: Three-Year Follow-up From the RESILIENT Randomized Trial:

Purpose To evaluate longer outcomes of primary nitinol stenting for the treatment of femoropopliteal lesions up to 15 cm long after these stents were found to have superior short-term patency vs. balloon angioplasty. Methods Two hundred and six patients (143 men; mean age 67 years) with intermittent claudication due to superficial femoral and proximal popliteal artery lesions were randomized (2:1) to treatment with nitinol stents or balloon angioplasty at 24 US and European centers and followed for 3 years. In that time, 15 patients died, 20 withdrew consent, and 10 were lost to follow-up, leaving 161 (78.2%) patients for 36-month assessment. Results The 12-month freedom from target lesion revascularization (TLR) was 87.3% for the stent group vs. 45.2% for the angioplasty group (p<0.0001). At 3 years, there was no difference in survival (90.0% vs. 91.7%, p=0.71) or major adverse events (75.2% vs. 75.2%, p=0.98) between the stent and angioplasty groups. Duplex ultrasound was not mandated after the first year, so stent patency could not be ascertained beyond 1 year, but freedom from TLR at 3 years was significantly better in the stent group (75.5% vs. 41.8%, p<0.0001), as was clinical success (63.2% vs. 17.9%, p<0.0001). At 18 months, a 4.1% (12/291) stent fracture rate was documented. Conclusion In this multicenter trial, primary implantation of a nitinol stent for moderate-length lesions in the femoropopliteal segment of patients with claudication was associated with better long-term results vs. balloon angioplasty alone.

Percutaneous angioscopy during coronary angioplasty using a steerable microangioscope

The feasibility of using a flexible, steerable angioscope to perform coronary angioscopy before and after percutaneous coronary angioplasty was tested. The microangioscope fits through an 8F coronary angioplasty guiding catheter and contains a multifiber viewing bundle incorporated into the body of a 4.3F balloon catheter with a central lumen for distal flushing and guide-wire passage. Angioscopy was performed without complications 45 times in 24 patients, including 6 patients with stable and 18 with unstable angina. Circumferential visualization of the target lesion was successful in 20 (83%) of the 24 patients and improved with operator experience. Excellent visualization of the target lesion was achieved in 16 (94%) of the last 17 patients. Plaque, thrombus and dissection were among the abnormal findings in the 20 patients (4 with stable, 16 with unstable angina) in whom circumferential viewing of the target lesion was achieved. In four patients with restenosis after angioplasty, the lesion morphology was distinctly different from that of lesions in arteries without prior angioplasty. In patients with stable angina, no thrombus or dissection was seen by angiography or angioscopy before angioplasty. In patients with unstable angina, thrombus was detected more frequently by angioscopy than by angiography before angioplasty (8 versus 2 of 16) and after (15 versus 2 of 16) angioplasty. Intimal dissection was also seen much more frequently by angioscopy than by angiography before angioplasty (7 versus 0 of 16) and after angioplasty (16 versus 7 of 16). It is concluded that high resolution percutaneous coronary angioscopy can be performed safely in conjunction with balloon angioplasty. Further investigation is needed before this diagnostic tool can be applied clinically.

Elevated brain natriuretic peptide predicts blood pressure response after stent revascularization in patients with renal artery stenosis.

Background—A significant number (20% to 40%) of hypertensive patients with renal artery stenosis will not have blood pressure improvement after successful percutaneous revascularization. Identifying a group of patients with refractory hypertension and renal artery stenosis who are likely to respond to renal stent placement would be beneficial. Methods and Results—Brain natriuretic peptide (BNP) was measured in 27 patients with refractory hypertension and significant renal artery stenosis before and after successful renal artery stent placement. This neuropeptide was elevated (median, 187 pg/mL; 25th to 75th percentiles, 89 to 306 pg/mL) before stent placement and fell within 24 hours of the successful stent procedure (96 pg/mL; 25th to 75th percentiles, 61 to 182 pg/mL; P=0.002), remaining low (85 pg/mL; 25th to 75th percentiles, 43 to 171 pg/mL) at follow-up. Clinical improvement in hypertension was observed in the patients with a baseline BNP >80 pg/mL (n=22) in 17 patients (77%) compared with 0% of the patients with a baseline BNP ≤80 pg/mL (n=5) (P=0.001). After correction for glomerular filtration rate, BNP was strongly correlated with improvement in hypertension. Conclusions—BNP is increased in patients with severe renal artery stenosis and decreases after successful stent revascularization. In addition, an elevated baseline BNP level of >80 pg/mL appears to be a good predictor of a blood pressure response after successful stent revascularization.

Predictive model to assess risk for cardiac allograft vasculopathy: an intravascular ultrasound study.

OBJECTIVES This study was performed to assess the influence and interdependence of immunologic and nonimmunologic risk factors in the development of cardiac allograft vasculopathy. Another primary objective was to establish a clinically useful model for risk assessment of cardiac allograft vasculopathy that would facilitate identifying those heart transplant recipients likely to have severe intimal proliferation and thereby at greater risk for adverse clinical events. BACKGROUND To our knowledge, no comprehensive intravascular ultrasound study has assessed the relative influences of both nonimmunologic and immunologic factors in the development of cardiac allograft vasculopathy, currently the major limitation to long-term cardiac allograft survival. METHODS Using a computer-assisted model of stepwise logistic regression, immunologic and nonimmunologic risk factors were evaluated to help identify the development of severe intimal thickening in 101 subjects who underwent intravascular ultrasound. Prospective validation of the findings was performed in a separate consecutive cohort of 37 heart transplant recipients, and the accuracy of this model to predict a relative risk > 1 for the development of severe intimal hyperplasia was assessed. RESULTS Significant independent predictors of severe intimal hyperplasia in this model included a donor age > 35 years, a first-year mean biopsy score > 1 (a measure not only of severity of rejection, but also of frequency of insidious rejection) and hypertriglyceridemia at two incremental levels of risk (150 to 250 mg/dl [1.70 to 2.83 mmol/liter] and > 250 mg/dl [2.83 mmol/liter]). Based on the absence (0) or presence (1) of these factors, 12 individual categories of risk were ascertained with increasing relative risks and predicted probabilities for severe intimal hyperplasia. Prospective validation of this model revealed a sensitivity and specificity of 70% and 90%, respectively, and the positive and negative predictive values were 85% and 80%, respectively. Additionally, subjects with severe intimal thickening had a four-fold higher cardiac event rate than those without severe intimal proliferation on intravascular ultrasound. CONCLUSIONS This study establishes a clinically useful predictive model that can be applied to individual heart transplant recipients to assess their risk for developing significant cardiac allograft vasculopathy and, thus, aids in the identification of patients at risk for cardiac events in whom closer surveillance and risk factor modification may be warranted.

An intravascular ultrasound study of the influence of angiotensin-converting enzyme inhibitors and calcium entry blockers on the development of cardiac allograft vasculopathy.

In conclusion, this intravascular ultrasound study suggests that treatment of cardiac transplant recipients with either ACE inhibitors or CEBs is associated with a decrease in the degree of vascular intimal hyperplasia at 1 year after transplantation. Thus, early intervention with CEBs or ACE inhibitors offers a preventive option for the devastating consequences of cardiac allograft vasculopathy.