In vivo assessment of coronary artery angioplasty and stent deployment from balloon pressure-volume data.

This study assessed the clinical and practical value of angioplasty balloon pressure-volume data, obtained by a computer-controlled balloon inflation device, during standard percutaneous coronary intervention (PCI) procedures. Stent deployment was studied for 57 lesions in 34 patients. Angiographic predilation data were available in 9 patients. Vessel lumen improvement with pre-dilation was determined using the area difference under the pressure-volume curves of two consecutive inflations and compared to the angiographically determined lumen improvement. Stent opening pressure, the inflation volume needed to unfold the stent and the shape of the pressure-volume curve were assessed for differences between stent sizes (diameter, length) and manufacturer types. A Pearson correlation of 0.8 between the pressure-volume area difference and the angiographic lumen improvement was significant (p = 0.01), confirming that pressure-volume curves are useful in assessing lumen improvement after pre-dilation. There was a significant difference in stent opening pressure between stent types but not between different stent sizes (length, diameter). The inflation volume measured during the unfolding process of the stent correlated with the calculated stent lumen when deployed (Pearson correlation: 0.65, p = 0.001). The shape of the pressure-volume curve during stent deployment illustrated differences between different stent sizes (length, diameter) during inflation. Pressure-volume curves obtained from an automatic balloon inflation device have shown their usefulness in providing additional feedback about lumen improvement and the mechanical characteristics and quality of stent deployment.

Survival following coronary angioplasty versus coronary artery bypass surgery in anatomic subsets in which coronary artery bypass surgery improves survival compared with medical therapy. Results from the Bypass Angioplasty Revascularization Investigation (BARI).

OBJECTIVES: We sought to compare survival after coronary artery bypass graft (CABG) and percutaneous transluminal coronary angioplasty (PTCA) in high-risk anatomic subsets. BACKGROUND: Compared with medical therapy, CABG decreases mortality in patients with three-vessel disease and two-vessel disease involving the proximal left anterior descending artery (LAD), particularly if left ventricular (LV) dysfunction is present. How survival after PTCA and CABG compares in these high-risk anatomic subsets is unknown. METHODS: In the Bypass Angioplasty Revascularization Investigation (BARI), 1,829 patients with multivessel disease were randomized to an initial strategy of PTCA or CABG between 1988 and 1991. Stents and IIb/IIIa inhibitors were not utilized. Since patients in BARI with diabetes mellitus had greater survival with CABG, separate analyses of patients without diabetes were performed. RESULTS: Seven-year survival among patients with three-vessel disease undergoing PTCA and CABG (n = 754) was 79% versus 84% (p = 0.06), respectively, and 85% versus 87% (p = 0.36) when only non-diabetics (n = 592) were analyzed. In patients with three-vessel disease and reduced LV function (ejection fraction <50%), seven-year survival was 70% versus 74% (p = 0.6) in all PTCA and CABG patients (n = 176), and 82% versus 73% (p = 0.29) among non-diabetic patients (n = 124). Seven-year survival was 87% versus 84% (p = 0.9) in all PTCA and CABG patients (including diabetics) with two-vessel disease involving the proximal LAD (n = 352), and 78% versus 71% (p = 0.7) in patients with two-vessel disease involving the proximal LAD with reduced LV function (n = 72). CONCLUSION: In high-risk anatomic subsets in which survival is prolonged by CABG versus medical therapy, revascularization by PTCA and CABG yielded equivalent survival over seven years.

Extent and distribution of in-stent intimal hyperplasia and edge effect in a non-radiation stent population.

Intimal hyperplasia within the body of the stent is the primary mechanism for in-stent restenosis; however, stent edge restenosis has been described after brachytherapy. Our current understanding about the magnitude of in vivo intimal hyperplasia and edge restenosis is limited to data obtained primarily from select, symptomatic patients requiring repeat angiography. The purpose of this study was to determine the extent and distribution of intimal hyperplasia both within the stent and along the stent edge in relatively nonselect, asymptomatic patients scheduled for 6-month intravascular ultrasound (IVUS) as part of a multicenter trial: Heparin Infusion Prior to Stenting. Planar IVUS measurements 1 mm apart were obtained throughout the stent and over a length of 10 mm proximal and distal to the stent at index and follow-up. Of the 179 patients enrolled, 140 returned for repeat angiography and IVUS at 6.4 +/- 1.9 months and had IVUS images adequate for analysis. Patients had 1.2 +/- 0.6 Palmaz-Schatz stents per vessel. There was a wide individual variation of intimal hyperplasia distribution within the stent and no mean predilection for any location. At 6 months, intimal hyperplasia occupied 29.3 +/- 16.2% of the stent volume on average. Lumen loss within 2 mm of the stent edge was due primarily to intimal proliferation. Beyond 2 mm, negative remodeling contributed more to lumen loss. Gender, age, vessel location, index plaque burden, hypercholesterolemia, diabetes, and tobacco did not predict luminal narrowing at the stent edges, but diabetes, unstable angina at presentation, and lesion length were predictive of in-stent intimal hyperplasia. In a non-radiation stent population, 29% of the stent volume is filled with intimal hyperplasia at 6 months. Lumen loss at the stent edge is due primarily to intimal proliferation.

Immediate and one-year outcome in patients with coronary bifurcation lesions in the modern era (NHLBI dynamic registry).

Balloon angioplasty of bifurcation lesions has been associated with lower success and higher complication rates than most other lesion types. The development of alternative strategies such as debulking and stenting, either alone or in combination, are currently used relatively often. The relative role of these newer approaches in improving acute or long-term outcome, however, remains uncertain. Of the total of 2,436 patients treated between July 1997 to February 1998 in the National Heart, Lung, and Blood Institute Dynamic Registry, there were 321 patients (group 1) with bifurcation lesions and 2,115 patients without any bifurcation lesions attempted (group 2). Treatment strategies in terms of major devices used were significantly different between the 2 groups (group 1 vs 2): balloon angioplasty alone (23.1% vs 26.5%), balloon angioplasty and rotational atherectomy (6.9% vs 4.4%), balloon angioplasty and stent (55.8% vs 59.9%), and balloon angioplasty, rotational atherectomy, and stent (10.3% vs 7%) with p <0.01. There were no significant differences between the groups in terms of age, gender, and frequency of prior myocardial infarction (MI) or coronary artery bypass graft surgery (CABG). Complete angiographic success was achieved in only 86% of bifurcation lesions versus 93.5% of nonbifurcation lesions (p <0.001). In-hospital complication rates were increased in patients with bifurcation lesions compared with the nonbifurcation group: MI, 3.7% versus 2.6%; CABG, 2.2% versus 1.1%; side branch occlusion, 7.3% versus 2.3% (p <0.001); and the composite of death, MI, and any CABG, 7.2% versus 5.0%. At 1-year follow-up, major adverse cardiac events were 25% higher in group 1 than in group 2 (32.1% vs 25.7%, p <0.05). We conclude that despite the widespread use of newer percutaneous devices, treatment of bifurcation lesions remains difficult and is associated with decreased success and increased complication rates compared with nonbifurcation lesions.

Detailed angiographic analysis of women with suspected ischemic chest pain (pilot phase data from the NHLBI-sponsored Women's Ischemia Syndrome Evaluation [WISE] Study Angiographic Core Laboratory).

The purpose of this study is to provide a contemporary qualitative and quantitative analysis of coronary angiograms from a large series of women enrolled in the Women's Ischemia Syndrome Evaluation (WISE) study who had suspected ischemic chest pain. Previous studies have suggested that women with chest pain have a lower prevalence of significant coronary artery disease (CAD) compared with men. Detailed analyses of angiographic findings relative to risk factors and outcomes are not available. All coronary angiograms were reviewed in a central core laboratory. Quantitative measurement of percent stenosis was used to assess the presence and severity of disease. Of the 323 women enrolled in the pilot phase, 34% had no detectable, 23% had measurable but minimal, and 43% had significant ( > 50% diameter stenosis) CAD. Of those with significant CAD, most had multivessel disease. Features suggesting complex plaque were identified in < 10%. Age, hypertension, diabetes mellitus, prior myocardial infarction (MI), current hormone replacement therapy, and unstable angina were all significant, independent predictors of presence of significant disease (p < 0.05). Subsequent hospitalization for a cardiac cause occurred more frequently in those women with minimal and significant disease compared with no disease (p = 0.001). The common findings of no and extensive CAD among symptomatic women at coronary angiography highlight the need for better clinical noninvasive evaluations for ischemia. Women with minimal CAD have intermediate rates of rehospitalization and cardiovascular events, and thus should not be considered low risk.

Changes in the practice of percutaneous coronary intervention: a comparison of enrollment waves in the National Heart, Lung, and Blood Institute (NHLBI) Dynamic Registry.

The National Heart, Lung, and Blood Institute Dynamic Registry includes 15 clinical sites in wave 1, and 16 sites in wave 2 as well as a data-coordinating center. The first wave of enrollment began in July 1997 and was completed in February 1998. The second wave began in February 1999 and ended in June 1999. There were a total of 2,526 patients in wave 1 and 2,109 patients in wave 2. Comprehensive pre-, intra-, and postprocedure (in-hospital) data were analyzed for changes between recruitment waves. Patients in wave 2 were more frequently nonwhite (p < or = 0.001), hypertensive by history (p < or = 0.001), had more significant noncardiac comorbidity (p < or = 0.01), and had more frequently undergone prior percutaneous coronary intervention (p < 0.05). Patients in wave 2 underwent percutaneous coronary intervention in a setting of acute coronary syndromes more frequently than wave 1 patients (p < or = 0.001). However, most interventions in both waves were performed on 1 vessel, irrespective of the extent of disease. Attempted lesions in wave 2 were longer (p < or = 0.001), less frequently totally occluded (p < or = 0.001), and more frequently in vessels with a prior stent (p < or = 0.01). Using the American Heart Association/American College of Cardiology lesion classification scheme, attempted lesions in wave 2 were less complex than those in wave 1 (p < or = 0.001). Stent use increased significantly from wave 1 (67%) to wave 2 (79%, p < or = 0.001) as did the use of platelet glycoprotein IIb/IIIa antagonists (wave 1, 24%; wave 2, 32%: p < 0.001). Procedural outcomes (angiographic success without major in-hospital adverse events) were excellent in both waves 1 (94.6%) and 2 (95.6%) and were not significantly different. However, the frequency of significant procedural coronary dissection and in- and out-of-laboratory abrupt closure were significantly less in wave 2 (p < or = 0.001) Discharge medications were more likely to include angiotensin-converting enzyme inhibitors, beta-adrenergic blocking agents, and hypolipidemic treatment in wave 2 than in wave 1 (p < or = 0.001). These data indicate a continuing aggressive approach to patient care over the time interval analyzed. Although overall procedural outcomes are excellent, procedural safety has been further enhanced. There is also a growing awareness of the importance of secondary prevention among interventional cardiologists.

Comparison of immediate and one-year outcome after coronary angioplasty of narrowing < 3 mm with those > or =3 mm ( the National Heart, Lung, and Blood Institute Dynamic Registry).

Balloon angioplasty of small coronary artery lesions has been associated with lower success and higher complication rates than large coronary artery lesions. This study evaluates the in-hospital and 1-year outcome of the treatment of small coronary artery lesions in the modern era of interventional cardiology and compares it with the outcome of treating large coronary artery lesions. Of 1,658 patients with a single lesion treated from July 1997 to February 1998 in the National Heart, Lung, and Blood Institute (NHLBI) Dynamic Registry, there were 587 patients with small coronary artery lesions (<3 mm) and 1,071 patients with large coronary artery lesions (> or =3 mm). Success, in-hospital, and 1-year outcomes between both groups were compared. Patients with lesions in small coronary arteries were more often women, insulin-treated diabetics, and had undergone more prior coronary bypass graft surgery. Conventional angioplasty alone was performed more often and angioplasty with stents was performed less often in the small coronary artery than in the large coronary artery group. Angiographic success was slightly lower in the small coronary artery group (94.2% vs 96.9%, p <0.05). Periprocedural and in-hospital complication rates were similar in both groups. Likewise, at 1-year follow-up, major adverse cardiac events including death, myocardial infarction, and coronary artery bypass graft surgery were relatively low and comparable between the 2 groups, although patients with small coronary arteries were more likely to undergo repeat revascularization (17.4% vs 13.6%, p <0.05). Treatment of lesions in small coronary arteries in the modern era is associated with high success and low complication rates, comparable to the treatment of large coronary artery lesions, although the incidence of repeat revascularization was significantly greater at follow-up even if stents were used.

Results of the study to determine rotablator and transluminal angioplasty strategy (STRATAS).

Rotational atherectomy is used to debulk calcified or complex coronary stenoses. Whether aggressive burr sizing with minimal balloon dilation (<1 atm) to limit deep wall arterial injury improves results is unknown. Patients being considered for elective rotational atherectomy were randomized to either an "aggressive" strategy (n = 249) (maximum burr/artery >0.70 alone, or with adjunctive balloon inflation < or = 1 atm), or a "routine" strategy (n = 248) (maximum burr/artery < or =0.70 and routine balloon inflation > or =4 atm). Patient age was 62 +/- 11 years. Fifty-nine percent routine and 60% aggressive strategy patients had class III to IV angina. Fifteen percent routine and 16% aggressive strategy patients had a restenotic lesion treated; lesion length was 13.6 versus 13.7 mm. Reference vessel diameter was 2.64 mm. Maximum burr size (1.8 vs 2.1 mm), burr/artery ratio (0.71 vs 0.82), and number of burrs used (1.9 vs 2.7) were greater for the aggressive strategy, p <0.0001. Final minimum lumen diameter and residual stenosis were 1.97 mm and 26% for the routine strategy versus 1.95 mm and 27% for the aggressive strategy. Clinical success was 93.5% for the routine strategy and 93.9% for the aggressive strategy. Creatine kinase-myocardial band (CK-MB) was >5 times normal in 7% of the routine versus 11% of the aggressive group. CK-MB elevation was associated with a decrease in rpm of >5,000 from baseline for a cumulative time >5 seconds, p = 0.002. At 6 months, 22% of the routine patients versus 31% of the aggressive strategy patients had target lesion revascularization. Angiographic follow-up (77%) showed minimum lumen diameter to be 1.26 mm in the routine group versus 1.16 mm in the aggressive group, and the loss index 0.54 versus 0.62. Dichotomous restenosis was 52% for the routine strategy versus 58% for the aggressive strategy. Multivariable analysis indicated that left anterior descending location (odds ratio 1.67, p = 0.02) and operator-reported excessive speed decrease >5,000 rpm (odds ratio 1.74, p = 0.01) were significantly associated with restenosis. Thus, the aggressive rotational atherectomy strategy offers no advantage over more routine burr sizing plus routine angioplasty. Operator technique reflected by an rpm decrease of >5,000 from baseline is associated with CK-MB elevation and restenosis.

Percutaneous coronary intervention in the current era compared with 1985-1986: the National Heart, Lung, and Blood Institute Registries.

BACKGROUND: Although refinements have occurred in coronary angioplasty over the past decade, little is known about whether these changes have affected outcomes. METHODS AND RESULTS: Baseline features and in-hospital and 1-year outcomes of 1559 consecutive patients in the 1997-1998 Dynamic Registry who were having first coronary intervention were compared with 2431 patients in the 1985-1986 National Heart, Lung, and Blood Institute Registry. Compared with patients in the 1985-1986 Registry, Dynamic Registry patients were older (mean age, 62 versus 58 years; P:<0.001) and more often female (32.1% versus 25.5%; P:<0.001). In the Dynamic Registry, procedures were more often performed for acute myocardial infarction (22.9% versus 9.9%; P:<0.001) and treated lesions were more severe (84.5% versus 82.5% diameter reduction; P:<0.001), thrombotic (22.1% versus 11.3%; P:<0.001) or calcified (29.5% versus 10.8%; P:<0.001). Stents were used in 70.5% of Dynamic Registry patients, whereas 1985-1986 patients received balloon angioplasty alone. Procedural success was higher in the Dynamic Registry (92.0% versus 81.8%; P:<0.001) and the rate of in-hospital death, myocardial infarction, and emergency coronary bypass surgery combined was lower (4.9% versus 7.9%; P:=0.001) than in the 1985-1986 Registry. The 1-year rate for CABG was lower in the Dynamic Registry (6.9% versus 12.6%; P:<0.001). CONCLUSIONS: Although Dynamic Registry patients had more unstable and complex coronary disease than those in the 1985-1986 Registry, their rate of procedural success was higher whereas rates of complications and subsequent CABG were lower. Results of percutaneous coronary intervention have improved substantially over the past decade.

Long-term clinical outcome in the Bypass Angioplasty Revascularization Investigation Registry: comparison with the randomized trial. BARI Investigators.

BACKGROUND: The Bypass Angioplasty Revascularization Investigation (BARI) included 4039 patients with multivessel coronary artery disease; 1829 consented to randomization, and 2010 did not but were followed up in a registry. Thus, we can evaluate the outcome of physician-guided versus random assignment of percutaneous transluminal coronary angioplasty (PTCA) versus coronary artery bypass graft surgery (CABG). METHODS AND RESULTS: We compared the baseline features and outcomes for PTCA and CABG in the overall registry and its predesignated subgroups. We assessed the impact of treatment by choice versus random assignment by comparing the results in the registry with those of the randomized trial. Statistical adjustments for differences in baseline characteristics were made. Within the registry, nearly twice as many patients were selected for PTCA (1189) as CABG (625); mortality at 7 years was similar for PTCA (13.9%) and CABG (14.2%) (P=0.66) before and after adjustment for baseline differences between patients selected for PTCA versus CABG (adjusted RR, 1.02; P=0.86). In contrast to the randomized trial, the 7-year mortality rate of treated diabetics in the registry was equally high (26%) with PTCA or CABG. Seven-year mortality was higher for patients undergoing PTCA in the randomized trial than in the registry (19.1% versus 13.9%, P<0.01) but not for those undergoing CABG (15.6% versus 14.2%, P=0.57). The adjusted relative mortality risk for PTCA in the randomized versus registry population was 1.17 (P=0.16). CONCLUSIONS: BARI physicians were able to select PTCA rather than CABG for 65% of registry patients who underwent revascularization without compromising long-term survival either in the overall population or in treated diabetics.

Heparin infusion prior to stenting (HIPS) trial: final results of a prospective, randomized, controlled trial evaluating the effects of local vascular delivery on intimal hyperplasia.

BACKGROUND: Local delivery of pharmacologic agents or genes at the site of angioplasty is a promising approach to reduce restenosis. However, there are unresolved questions concerning the safety and feasibility of local vascular delivery in clinical practice as well as the efficacy of delivered drug. To this end, the safety, feasibility, and efficacy of local delivery of heparin were evaluated in the Heparin Infusion Prior to Stenting (HIPS) trial. METHODS AND RESULTS: A total of 179 patients were enrolled in this multicenter, randomized, prospective, core laboratory-evaluated trial. Patients were randomly assigned to 5000 U heparin either administered to the coronary artery lumen or infused into the arterial wall immediately after angioplasty and before stent placement. End points included procedural events and clinical, angiographic, and intravascular ultrasound events at 6 months. Patient groups were evenly matched. There was no difference in the incidence of arterial injury, defined as an increase in arterial dissection, acute closure, or decrease in Thrombolysis In Myocardial Infarction grade blood flow in the group receiving local delivery. At follow-up there was no difference in the major adverse event rate between intraluminal (22.7%) and local groups (24.7%). There was no difference between intraluminal and local therapy in the angiographic in-stent restenosis rate (12.5%, 12.7%) or the in-stent volumetric analysis by intravascular ultrasound (IVUS) (37.19 +/- 20. 86 mm(3) vs 43.79 +/- 25.52 mm(3)). CONCLUSIONS: Local delivery of 5000 U heparin into the arterial wall before stent implantation is safe and feasible. There was not a favorable effect of locally delivered heparin on clinical, angiographic, or IVUS end points of restenosis. The use of IVUS to measure volume of intimal hyperplasia in a multicenter, core laboratory-controlled trial is feasible.

Acute and nine-month clinical outcomes after "suboptimal" coronary stenting: results from the STent Anti-thrombotic Regimen Study (STARS) registry.

OBJECTIVES: This registry collected the 30-day and 9-month clinical outcomes of patients whose coronary stent implantation was suboptimal, and compared them with the cohort of patients with "optimal" stenting in the randomized portion of the STent Anti-thrombotic Regimen Study (STARS) trial. BACKGROUND: Although "optimal" stenting combined with an aspirin and ticlopidine regimen carries a low (0.5%) incidence of subacute stent thrombosis, only limited data are available for patients in whom stents are deployed suboptimally. METHODS: In the STARS, 312 (15.9%) of 1,965 patients enrolled were excluded from participation in the randomized trial based on a perceived "suboptimal" result of coronary stenting. Of these, 265 patients met prespecified criteria for suboptimal stenting, and were followed in a parallel registry, which was compared with the randomized STARS optimal stenting cohort. The primary end point was a 30-day composite of death, emergent target lesion revascularization, angiographic thrombosis of the target vessel without revascularization and nonfatal myocardial infarction (MI) unrelated to direct procedural complications. RESULTS: Registry patients had a similar frequency of the primary end point compared with the overall randomized cohort (3.0% vs. 2.2%), with this end point correlating to use of multiple stents, smaller final lumen diameter and absence of ticlopidine from the poststent regimen. Overall 30-day mortality (1.1% vs. 0.06%, p = 0.009) and periprocedural non-Q wave MI (8.7% vs. 4.2%, p = 0.003) were more frequent in registry patients, and appeared to be related to acute procedural complications. Clinical restenosis was significantly higher for registry patients (26.8% vs. 16.0%, p = 0.001), relating to greater prevalence of independent predictors such as smaller final lumen diameter and multiple stent use. CONCLUSIONS: In the STARS registry, the inability to perform optimal stenting correlated with smaller final lumen diameter and longer stent length. With ticlopidine-containing regimens, the acute clinical results of "suboptimal" stent deployment are clinically acceptable, although they are not quite as good as those of optimal stenting using similar drug therapy.

Incidence and predictors of target vessel revascularization following percutaneous transluminal coronary angioplasty: a report from the National Heart, Lung, and Blood Institute Percutaneous Transluminal Coronary Angioplasty Registry.

We sought to determine the rate of target vessel revascularization (TVR) after percutaneous transluminal coronary angioplasty (PTCA) and to determine factors that predispose to its occurrence. The 10-year outcome of 2,262 patients in the National Heart, Lung, and Blood institute PTCA Registry was analyzed to determine the incidence and characterize predictors of TVR. TVR was performed in 30.4% of patients. Male gender (relative risk [RR] 1.26; p <0.05), diabetes (RR 1.57; p <0.001), multiple discrete lesions (RR 1.38, p <0.01), diffuse lesions (RR 1.27; p <0.05), and calcium at the lesion site (RR 1.25; p <0.05) were predictors for TVR. TVR was performed early (< or = 1 year) in 18.3% and late (> 1 year) in 12.2%. Age > or = 65 years (RR 1.24; p <0.05), congestive heart failure (RR 1.70; p <0.05), acute coronary insufficiency (RR 1.28; p <0.05), and left anterior descending lesion location (RR 1.34, p <0.01) were significant predictors of early versus late TVR by multivariate analysis. Coronary artery bypass grafting (CABG) rather than PTCA was the TVR procedure in 21% of patients undergoing early TVR and 58% of those undergoing late TVR. Significant independent predictors of CABG as the TVR procedure were multivessel disease (RR 1.97; p <0.001), presence of collateral vessels (RR 1.81; p <0.05), diffuse (RR 1.89; p <0.01), or occluded (RR 1.82; p <0.05) target lesions, and a greater residual stenosis after the initial PTCA (RR 1.19; p <0.001). Age > or = 65 years (RR 0.65; p <0.05) conferred a lower risk for CABG.

Effects of intracoronary beta-radiation therapy after coronary angioplasty: an intravascular ultrasound study.

BACKGROUND: Endovascular radiation is emerging as a potential solution for the prevention and treatment of restenosis. Its effects on the morphology of unstented vessels cannot be determined by angiography and therefore require the use of intravascular ultrasound. METHODS AND RESULTS: Through a 5F noncentered catheter for delivery of a 90Sr/Y source train, 12, 14, or 16 Gy at 2 mm was delivered to native coronary arteries after successful balloon angioplasty in 30 patients. Four patients required stent deployment in the first week. Quantitative coronary angiography and IVUS were performed during the initial procedure and at 6-month follow-up. Binary angiographic restenosis was present in 3 of 30 patients, with target lesion and vessel revascularization performed in 3 and 5 patients, respectively. Angiographic late loss was -0.02+/-0.60 mm, with a -0.09+/-0.46 loss index. IVUS demonstrated no significant reduction in lumen area (from 5.69+/-1.72 mm2 after treatment to 6. 04+/-2.63 mm2 at follow-up), with no significant change in external elastic membrane area (13.71+/-4.54 to 14.22+/-4.71 mm2) over the 6-month follow-up. Wall area was 8.01+/-3.85 mm2 after radiation therapy and 8.19+/-3.44 mm2 at follow-up (P=NS). No significant differences were noted between the different dose groups. CONCLUSIONS: beta-Radiation therapy resulted in a low restenosis rate with negligible late loss by angiography. By IVUS, beta-radiation was shown to inhibit neointima formation, with no reduction of total vessel area at 6-month follow-up.