R. Jeffrey Snell

Predictors of late cardiac events following treatment with Sr-90 β-irradiation for instent restenosis

BACKGROUND Intracoronary radiation therapy (IRT) with Sr-90 using the Novoste Beta-Cath system has been shown to be an effective therapy for instent restenosis (ISR), but the temporal occurrence of cardiac events and the predictors of late complications require further investigation. METHODS We analyzed the demographics, lesion characteristics and clinical outcomes of 138 consecutive patients with ISR treated with IRT from September 1998 to March 2002. Major adverse cardiac events (MACE) were defined as death, myocardial infarction (MI) or target vessel revascularization (TVR). Characteristics of early (< or =8 months) and late (>8 months) failures were analyzed. RESULTS Thirty-two (23.1%) of 138 patients had MACE on follow-up; 25% (8/32) of failures occurred late after treatment with IRT. A comparison of the clinical and angiographic profile of early and late failures using univariate analysis indicates no correlations to late failure following IRT. Duration to failure after IRT was 14.25+/-3.69 months in the late group compared to 4.63+/-2.86 months in the early group (P<.001). CONCLUSIONS Late MACE after IRT with Sr-90 for ISR occur beyond the traditional period for clinical restenosis in 25% of cases and are difficult to predict. Further study is warranted to identify patients at risk for the development of late complications after IRT.

Carotid artery stent type influences duplex ultrasonography derived peak systolic velocity: Findings of an in-vitro model

Objective: The goal of this study is to evaluate the effect of stenting on Doppler ultrasonography (DU) [velocity] signals in an in‐vitro carotid model. Background: Considerable debate exists about whether DU overestimates velocity signals and thus the degree of stenosis in previously stented carotid arteries. Methods: Constant, pulsatile flow was simulated with an experimental circulatory system containing a nonstenotic ovine internal carotid artery segment. Peak systolic velocity (PSV) and peak diastolic velocity were measured with an intravascular flow wire (FW) and DU. Velocities were evaluated at five predetermined locations within the vessel immediately prior to and following stent placement. Results: Eleven stents were implanted. DU‐derived PSV increased significantly following placement of the X‐Act stent (80 ± 26 cm/sec [pre] vs. 102 ± 29 cm/sec [post], P = 0.02), while FW‐derived PSV (65 ± 23 cm/sec [pre] vs. 66 ± 9 cm/sec [post], P = 0.93) did not change. The Precise stent did not influence PSV with either method (DU: 76 ± 28 cm/sec [pre] vs. 72 ± 35 cm/sec [post], P = 0.95;), while the Acculink stent showed a trend towards a reduction in DU (69 ± 37 cm/sec [pre] vs. 51 ± 10 cm/sec [post], P = 0.075) and FW (50 ± 27 cm/sec [pre] vs. 40 ± 12 cm/sec [post], P = 0.14) derived PSV. Peak diastolic velocity revealed similar trends as PSV signals depending on the type of stent used. Conclusions: Stent type may have significant impact on DU derived velocity signals. DU seems to overestimate PSV in carotid arteries treated with the X‐Act stent, but not with the Precise or Acculink stent. Larger scale clinical comparison of various stent types and their impact on DU are needed in order to clarify the value of DU surveillance following carotid artery stenting.

Clinical outcomes of patients treated with the cutting balloon and Sr-90 β-irradiation for instent restenosis

BACKGROUND The cutting balloon (CB) is an emerging therapy for the treatment of instent restenosis (ISR), but its impact on the clinical outcomes of patients treated with intracoronary radiation therapy (IRT) with Sr-90 compared with conventional PTCA and IRT is not clearly defined. METHODS We compared the baseline demographics, angiographic characteristics and clinical outcomes of 102 consecutive patients with ISR treated either with CB+IRT (n=45) or with conventional PTCA+IRT (n=57). The combined endpoint was the occurrence of major adverse cardiac events (MACE), which was defined as a composite of death, myocardial infarction (MI) or target vessel revascularization (TVR) at 6 months. RESULTS The CB+IRT group had a shorter mean lesion length (14.3+/-6.5 vs. 21.1+/-15.7, P=.009), and greater utilization of glycoprotein IIb/IIIa inhibitors during the procedure (48.9% vs. 26.3%, P=.02) compared to the PTCA+IRT group. There were no significant differences in the baseline demographics, angiographic and procedural results, or subsequent MACE at 6 months between the two groups. CONCLUSION The strategy of CB+IRT using Sr-90 for ISR is associated with similar procedural and clinical outcomes compared to conventional PTCA+IRT. Further study is warranted to determine which patient subgroups would derive the most benefit from this approach.

The Contemporary Management of Acute Myocardial Infarction

The contemporary management of acute myocardial infarction continues to evolve rapidly. The ultimate goal of therapy is timely, complete, and sustained myocardial reperfusion. There is a powerful time-dependent effect on mortality, and thus the balance between the time and likelihood of maximal reperfusion is crucial in deciding whether to use primary percutaneous balloon angioplasty or thrombolysis as the initial reperfusion strategy. Newer thrombolytic agents allow for equivalent coronary reperfusion compared with the standard accelerated alteplase (tPA) regimen with the advantage of easier dosing regimens. Low molecular weight heparin has been shown to be superior to unfractionated heparin and likely will be the standard of care in the near future. The use of glycoprotein IIb/IIIa inhibitors has been shown to decrease the short- and long-term complication rates in patients with acute coronary syndromes treated medically and with percutaneous coronary interventions; however, the choice of the optimal agent and dosing regimen in various clinical settings remains controversial. Combination therapy with low-dose fibrinolytics, glycoprotein IIb/IIIa inhibitors, and low molecular weight heparin, with or without subsequent early planned percutaneous coronary interventions, may provide the optimal strategy for maximal coronary reperfusion, but the results of large, randomized mortality trials currently underway need to be analyzed. Risk stratification will continue to play a major role in determining which patients should receive a specific therapy. The care of the patient with an acute myocardial infarction will continue to be a challenge requiring the proper selection from the vast pharmaceutic and interventional options available.

Correlates of failure following treatment with Sr-90 beta irradiation for in-stent restenosis.

We sought to determine the correlates of failure following intracoronary radiation therapy (IRT) with Sr‐90 using the Novoste Beta‐Cath system for the treatment of in‐stent restenosis (ISR) in a broad range of patients. IRT has been shown to be more efficacious compared to placebo for the treatment of ISR in large randomized trials. However, even in patients treated with IRT, major adverse cardiac events occur in approximately 20% of cases on follow‐up. This trial sought to elucidate the correlates of failure following successful IRT for ISR. To determine the correlates of IRT failure, we retrospectively compared the demographics, lesion characteristics, and clinical outcomes of 102 consecutive patients with ISR treated with Sr‐90 from September 1998 to July 2001. IRT failure was defined as death, myocardial infarction (MI), or target vessel revascularization (TVR) due to repeat ISR on follow‐up. A comparison of the clinical and angiographic profile of IRT failures (n = 16) vs. IRT successes (n = 86) revealed that a history of smoking (75% vs. 40%; P = 0.012), current use of calcium channel blockers (84% vs. 45%; P = 0.013), ostial location of target lesion (44% vs. 16%; P = 0.020), and mean posttreatment minimal luminal diameter (MLD; 1.64 ± 0.19 vs. 2.21 ± 0.29 mm; P < 0.001), respectively, were correlated with failure using univariate analysis. After multivariate regression analysis, the correlates of failure that remained significant were treatment of an ostial lesion (OR = 31.2; 95% CI = 2.6–382.7; P = 0.007) and final posttreatment MLD (P < 0.001). Ostial location of target lesion and smaller posttreatment MLD are correlated with subsequent death, MI, and TVR following therapy with Sr‐90 for ISR. Cathet Cardiovasc Intervent 2003;59:176–183.

Visual assessment of procedural results following treatment with Sr-90 β-radiation for instent restenosis

BACKGROUND Visual assessment (VA) of postprocedural % diameter stenosis (DS) is used routinely in clinical practice to determine the adequacy of coronary intervention. Although VA has been shown to underestimate final %DS after balloon angioplasty compared to quantitative coronary angiography (QCA), the impact of this effect on clinical outcomes following treatment with intracoronary radiation therapy (IRT) with Sr-90 for instent restenosis (ISR) is unknown. METHODS To determine the effect of VA on the rate of major adverse cardiac events (MACEs) after IRT for ISR, we compared the clinical outcomes of 102 consecutive patients based on postprocedural %DS by QCA vs. %DS by VA. MACE was defined as death, M1 or need for target vessel revascularization (TVR). RESULTS MACE rates for the 102 consecutive patients grouped according to postprocedural %DS by QCA and VA were compared. The mean %DS by QCA was 30.7%, while the mean %DS by VA was 12.5%. The mean %DS by VA across the QCA subgroups were 13.67%, 10.71% and 13.37%, respectively (P = .244). Fifty-two patients (51.0%) had %DS > 30% by QCA with the highest MACE percentage occurring in this subgroup. CONCLUSION VA underestimated the %DS compared to QCA, and it was associated with worse MACE following treatment with Sr-90 for ISR.