Devices for Distal Protection During Percutaneous Coronary Revascularization

Coronary microcirculation in nonculprit vessel territory in reperfused acute myocardial infarction

BACKGROUND

There is an ongoing debate on the extension of reperfusion-related microvascular damage (MVD) throughout the remote noninfarcted myocardial regions in patients with ST-elevation myocardial infarction (STEMI) that undergo primary percutaneous intervention (pPCI). The aim of this study was to elucidate the impact of reperfusion on remote microcirculatory territory by analyzing hemodynamic alterations in the nonculprit-vessel in relation to reperfusion.

METHODS

A total of 20 patients with STEMI undergoing pPCI were included. Peri-reperfusion temporal changes in hemodynamic parameters were obtained in angiographically normal nonculprit vessels before and 1-h after reopening of the culprit vessel. Intracoronary pressure and flow velocity data were compared using pairwise analyses (before and 1-h after reperfusion).

RESULTS

In the non-culprit vessel, compared to the pre-reperfusion state, mean resting average peak velocity (33.4 ± 9.4 to 25.0 ± 4.9 cm/s, P < 0.001) and mean hyperemic average peak velocity (53.5 ± 14.4 to 42.1 ± 10.66 cm/s, P = 0.001) significantly decreased; whereas baseline (3.2 ± 1.0 to 4.0 ± 1.0 mmHg.cm^-1.s, P < 0.001) and hyperemic microvascular resistance (HMR) (1.9 ± 0.6 to 2.4 ± 0.7 mmHg.cm^-1.s, P < 0.001) and mean zero flow pressure (Pzf) values (32.5 ± 6.9 to 37.6 ± 8.3 mmHg, P = 0.003) significantly increased 1-h after reperfusion. In particular, the magnitude of changes in HMR and Pzf values following reperfusion were more prominent in patients with larger infarct size and with higher extent of MVD in the culprit vessel territory.

CONCLUSION

Reperfusion-related microvascular injury extends to involve remote myocardial territory in relation to the magnitude of the adjacent infarction and infarct-zone MVD. (GUARD Clinical TrialsNCT02732080).

Current State of the Art in Approaches to Saphenous Vein Graft Interventions

Saphenous vein grafts (SVGs), used during coronary artery bypass graft surgery for severe coronary artery disease, are prone to degeneration and occlusion, leading to poor long-term patency compared with arterial grafts. Interventions used to treat SVG disease are susceptible to high rates of periprocedural MI and no-reflow. To minimise complications seen with these interventions, proper stents, embolic protection devices (EPDs) and pharmacological selection are crucial. Regarding stent selection, evidence has demonstrated superiority of drug-eluting stents over bare-metal stents in SVG intervention. The ACCF/AHA/SCA American College of Cardiology/American Heart Association Task Force on Clinical Practice Guidelines and the Society for Cardiovascular Angiography and Interventions guidelines recommend the use of EPDs during SVG intervention to decrease the risk of periprocedural MI, distal embolisation and no-reflow. The optimal pharmacological treatment for slow or no-reflow remains unclear, but various vasodilators show promise.

The Role of Nitric Oxide during Sonoreperfusion of Microvascular Obstruction

Rationale: Microembolization during PCI for acute myocardial infarction can cause microvascular obstruction (MVO). MVO severely limits the success of reperfusion therapies, is associated with additional myonecrosis, and is linked to worse prognosis, including death. We have shown, both in in vitro and in vivo models, that ultrasound (US) and microbubble (MB) therapy (termed “sonoreperfusion” or “SRP”) is a theranostic approach that relieves MVO and restores perfusion, but the underlying mechanisms remain to be established.

Objective: In this study, we investigated the role of nitric oxide (NO) during SRP.

Methods and results: We first demonstrated in plated cells that US-stimulated MB oscillations induced a 6-fold increase in endothelial nitric oxide synthase (eNOS) phosphorylation in vitro. We then monitored the kinetics of intramuscular NO and perfusion flow rate responses following 2-min of SRP therapy in the rat hindlimb muscle, with and without blockade of eNOS with LNAME. Following SRP, we found that starting at 6 minutes, intramuscular NO increased significantly over 30 min and was higher than baseline after 13 min. Concomitant contrast enhanced burst reperfusion imaging confirmed that there was a marked increase in perfusion flow rate at 6 and 10 min post SRP compared to baseline (>2.5 fold). The increases in intramuscular NO and perfusion rate were blunted with LNAME. Finally, we tested the hypothesis that NO plays a role in SRP by assessing reperfusion efficacy in a previously described rat hindlimb model of MVO during blockade of eNOS. After US treatment 1, microvascular blood volume was restored to baseline in the MB+US group, but remained low in the LNAME group. Perfusion rates increased in the MB+US group after US treatment 2 but not in the MB+US+LNAME group.

Conclusions: These data strongly support that MB oscillations can activate the eNOS pathway leading to increased blood perfusion and that NO plays a significant role in SRP efficacy.

Coronary covered stents

Covered stents offer an effective bail-out strategy in vessel perforations, are an alternative to surgery for the exclusion of coronary aneurysms, and have a potential role in the treatment of friable embolisation-prone plaques. The aim of this manuscript is to offer an overview of currently available platforms and to report results obtained in prior studies.

A review of strategies for infarct size reduction during acute myocardial infarction

Advances in medical and interventional therapy over the last few decades have revolutionized the treatment of acute myocardial infarction. Despite the ability to restore epicardial coronary artery patency promptly through percutaneous coronary intervention, tissue level damage may continue. The reported 30-day mortality after all acute coronary syndromes is 2 to 3%, and around 5% following myocardial infarction. Post-infarct complications such as heart failure continue to be a major contributor to cardiovascular morbidity and mortality. Inadequate microvascular reperfusion leads to worse clinical outcomes and potentially strategies to reduce infarct size during periods of ischemia-reperfusion can improve outcomes. Many strategies have been tested, but no single strategy alone has shown a consistent result or benefit in large scale randomised clinical trials. Herein, we review the historical efforts, current strategies, and potential novel concepts that may improve myocardial protection and reduce infarct size.

Effect of Thrombus Composition and Viscosity on Sonoreperfusion Efficacy in a Model of Micro-Vascular Obstruction

Distal embolization of micro-thrombi during stenting for myocardial infarction causes micro-vascular obstruction (MVO). We have previously shown that sonoreperfusion (SRP), a microbubble (MB)-mediated ultrasound (US) therapy, resolves MVO from venous micro-thrombi in vitro in saline. However, blood is more viscous than saline, and arterial thrombi that embolize during stenting are mechanically distinct from venous clot. Therefore, we tested the hypothesis that MVO created with arterial micro-thrombi are more resistant to SRP therapy compared with venous micro-thrombi, and higher viscosity further increases the US requirement for effective SRP in an in vitro model of MVO. Lipid MBs suspended in plasma with adjusted viscosity (1.1 cP or 4.0 cP) were passed through tubing bearing a mesh with 40-μm pores to simulate a micro-vascular cross-section; upstream pressure reflected thrombus burden. To simulate MVO, the mesh was occluded with either arterial or venous micro-thrombi to increase upstream pressure to 40 mmHg ± 5 mmHg. Therapeutic long-tone-burst US was delivered to the occluded area for 20 min. MB activity was recorded with a passive cavitation detector. MVO caused by arterial micro-thrombi at either blood or plasma viscosity resulted in less effective SRP therapy compared to venous thrombi. Higher viscosity further reduced the effectiveness of SRP therapy. The passive cavitation detector showed a decrease in inertial cavitation when viscosity was increased, while stable cavitation was affected in a more complex manner. Overall, these data suggest that arterial thrombi may require higher acoustic pressure US than venous thrombi to achieve similar SRP efficacy; increased viscosity decreases SRP efficacy; and both inertial and stable cavitation are implicated in observed SRP efficacy.

Early and midterm major adverse cardiac events in patient with saphenous vein graft using direct stenting or embolic protection device stenting

Background:

The treatment of an occluded saphenous vein graft (SVG) with percutaneous coronary intervention may encounter major adverse cardiac events (MACE). MACE rates have been reduced significantly by using the embolic protection device (EPD).

Objectives:

The aim of this study was to clarify the risks and the benefits of embolic protection devices.

Patients and Methods:

In a prospective, non-randomized observational study, patients aged 33 to 85 years old who underwent elective percutaneous coronary intervention due to SVG stenosis at our tertiary care center were enrolled between 2009 and 2011. The incidence rates of adverse events, including MACE, were obtained during the patients’ hospitalization and at 30-day and 6-month follow-up. MACE included death, Q-wave and non-Q-wave myocardial infarction, in-stent thrombosis, target lesion revascularization, and target vessel revascularization.

Results:

From 150 patients enrolled to the study, 128 (85.3%) patients underwent direct stenting and the rest underwent the EPD procedure. In-hospital MACE occurred in 17.2% of the patients in the direct stenting group versus only 9.1% in the EPD group (P = 0.530). MACE incidence was gradually increased at one and 6-month follow-up periods in the direct stenting group (19.5% and 21.9%, respectively), and remained unchanged in the EPD group (9.1% at six-month follow-up). Multivariate logistic regression model showed that the stenting procedure type could not predict early and midterm MACE with the presence of baseline characteristics as cofounders.

Conclusions:

Despite the considerable lower early and midterm MACE rates, numerically following the EPD procedure compared to direct stenting, the difference in the MACE rates between the two groups was not significant.

Assessment of plaque composition by intravascular ultrasound and near-infrared spectroscopy: from PROSPECT I to PROSPECT II

Atherosclerosis is the main cause of coronary artery disease (CAD), which is today the leading cause of death worldwide and will continue to be the first in the world in 2030. Vulnerable coronary plaques are usually characterized by a high content of necrotic core, a thin inflamed fibrous cap (intense accumulation of macrophages) and scarce presence of smooth muscle cells. None of these characteristics can be estimated by coronary angiography, which on the contrary underestimates the magnitude of atherosclerotic burden, particularly in earlier stage disease when positive vascular remodeling may allow "normal" lumen caliber despite substantial vascular wall plaque. The recognition of the ubiquity of substantial but non-flow limiting lesions that may be at high risk for subsequent plaque rupture has resulted in a paradigm shift in thinking about the pathophysiology of CAD, with the focus no longer solely on the degree of arterial luminal narrowing. This growing need for more information about coronary atherosclerosis in order to identify patients and lesions at risk for complications during PCI and for future adverse cardiac events has been the primary impetus for the development of novel intracoronary imaging methods able to detect plaque composition, in particular presence of a necrotic core/lipid pool, such as intravascular ultrasound virtual histology and near-infrared spectroscopy. These imaging technologies and their clinical and clinical/research applications are discussed in detail.

Filter neuroprotection of a single patent internal carotid artery during transapical aortic valve implantation

The finding of a mobile calcific plaque attached to the aortic valve cusp during transcatheter aortic valve implantation (TAVI/TAVR) necessitated utilization of an embolic protection device, for cerebral protection. We report the urgent but successful deployment of such a filter in a patient with a single patent internal carotid artery. Although stroke rates observed in first-generation TAVI trials were higher than those reported following conventional open aortic valve replacement, adjunctive neuroprotective measures, particularly in patients with a large amount of threatened cerebral territory, may minimize potential neurologic injury.

An update on coronary bypass graft intervention

Coronary artery bypass grafting (CABG) remains one of the most common surgical procedures. In spite of great advancements like arterial grafts and off-pump bypass procedure, recurrent ischaemia may ensue with the lesions of the graft. Early postoperative ischaemia (<30 days) is due to graft occlusion or stenosis, and percutaneous coronary intervention (PCI) is frequently feasible. Late postoperative ischaemia (>3 years) is most often due to a saphenous vein graft (SVG) lesion. Multiple diseased grafts, reduced left ventricular function, and available arterial conduits favour repeat CABG, whereas, a patent left internal mammary artery to left anterior descending favours PCI. Embolic protection reduces atheroembolic myocardial infarction during PCI of SVG and should be routinely used in treatment of SVG lesions. A variety of vasodilators may reduce the risk of or mitigate the consequences of no-reflow. Drug-eluting stents reduce restenosis in SVG grafts, and have become the default strategy for many interventionalists.

Spontaneous and procedural plaque embolisation in native coronary arteries: pathophysiology, diagnosis, and prevention

The detachment of atherothrombotic material from the atherosclerotic coronary plaque and downstream embolisation is an underrecognized phenomenon and it causes different degrees of impairment of the coronary microcirculation. During treatment of obstructive atherosclerotic plaque by percutaneous coronary intervention (PCI) distal embolisation (DE) is considered to be inevitable and it is associated with potential clinical and prognostic implications. This review aims to assess the main aspects of both spontaneous and procedural DE, analyze their different pathophysiology, provide specific insights on the main diagnostic tools for their identification, and finally focus on the main strategies for their treatment and prevention.

Degenerated Saphenous Vein Graft Intervention: Should We Target the Native Vessel instead?

Coronary interventions of degenerated saphenous vein grafts (SVGs) continue to present a management challenge. Although repeat coronary artery bypass grafting (CABG) remains a significant risk factor for operative mortality, percutaneous coronary intervention (PCI) is still associated with a high risk for periprocedural events. There is a lack of consensus on the optimal treatment strategy for patients with severe stenosis of SVGs. It is imperative to review the characteristics of native versus SVG disease, risk factors for complications after SVG intervention, procedural treatment strategies important to the decision on which therapeutic strategy to follow, and measures to mitigate the risks of periprocedural complications.

Meta-analysis of plaque composition by intravascular ultrasound and its relation to distal embolization after percutaneous coronary intervention

Controversies exist regarding the association between plaque composition and distal embolization phenomenon after percutaneous coronary intervention (PCI). We evaluated the effect of plaque characteristics on embolization after PCI by grayscale and virtual histology-intravascular ultrasound (IVUS). We searched PubMed, Ovid MEDLINE, and Cochrane databases for IVUS studies evaluating the coronary plaque characteristics in no reflow, distal embolization, and periprocedural myocardial infarction after PCI. Sixteen studies were included, totaling 1,697 patients who underwent PCI (292 patients with embolization and 1,405 patients without embolization). At the minimum lumen sites, the external elastic membrane (weighted mean difference 2.38 mm(2), 95% confidence interval [CI] 1.02 to 3.74) and the plaque and media cross-sectional areas (weighted mean difference 2.44 mm(2), 95% CI 1.44 to 3.45) were significantly greater in the embolization group than in the no embolization group. Pooled analysis showed that the absolute necrotic core volume (standardized mean difference 0.49, 95% CI 0.13 to 0.85), absolute (standardized mean difference 0.73, 95% CI 0.14 to 1.31) and relative (standardized mean difference 1.02, 95% CI 0.72 to 1.31) necrotic core areas at the minimum lumen sites were significantly greater in the embolization group than in the no embolization group, but the other plaque components were similar in the 2 groups. In conclusion, the necrotic core component derived from virtual histology-IVUS and the morphologic characteristics of plaque derived from grayscale IVUS are closely related to the distal embolization phenomenon after PCI.

Percutaneous revascularization for ischemic nephropathy: the past, present, and future

Occlusion of the renal arteries can threaten the viability of the kidney when severe, in addition to accelerating hypertension and circulatory congestion. Renal artery stenting procedures have evolved from a treatment mainly for renovascular hypertension to a maneuver capable of recovering threatened renal function in patients with “ischemic nephropathy” and improving management of congestive heart failure. Improved catheter design and techniques have reduced, but not eliminated hazards associated with renovascular stenting. Expanded use of endovascular stent grafts to treat abdominal aortic aneurysms has introduced a new indication for renal artery stenting to protect the renal circulation when grafts cross the origins of the renal arteries. Although controversial, prospective randomized trials to evaluate the added benefit of revascularization to current medical therapy for atherosclerotic renal artery stenosis until now have failed to identify major benefits regarding either renal function or blood pressure control. These studies have been limited by selection bias and have been harshly criticized. While studies of tissue oxygenation using blood oxygen level dependent (BOLD) MR establish that kidneys can adapt to reduced blood flow to some degree, more severe occlusive disease leads to cortical hypoxia associated with microvascular rarefication, inflammatory injury and fibrosis. Current research is directed toward identifying pathways of irreversible kidney injury due to vascular occlusion and to increase the potential for renal repair after restoring renal artery patency. The role of nephrologists likely will focus upon recognizing the limits of renal adaptation to vascular disease and identifying kidneys truly at risk for ischemic injury at a time point when renal revascularization can still be of benefit to recovering kidney function.

Embolic protection devices in saphenous vein graft and native vessel percutaneous intervention: a review

The clinical benefit of percutaneous intervention (PCI) depends on both angiographic success at the site of intervention as well as the restoration of adequate microvascular perfusion. Saphenous vein graft intervention is commonly associated with evidence of distal plaque embolization, which is correlated with worse clinical outcomes. Despite successful epicardial intervention in the acute MI patient treated with primary PCI, distal tissue perfusion may still be absent in up to 25% of cases [1-3]. Multiple devices and pharmacologic regimens have been developed and refined in an attempt to protect the microvascular circulation during both saphenous vein graft intervention and primary PCI in the acute MI setting. We will review the evidence for various techniques for embolic protection of the distal myocardium during saphenous vein graft PCI and primary PCI in the native vessel.

Distal protection devices in primary percutaneous coronary intervention of native coronary artery lesions: a meta-analysis of randomized controlled trials

OBJECTIVE

The use of embolic protection devices to decrease major adverse cardiac events (MACEs) in patients with saphenous vein graft lesions is considered class I therapy by the recent practice guidelines. However, the benefits of adjunctive protection devices to prevent distal embolization in patients with native coronary artery lesions are still a matter of debate. Therefore, we performed the meta-analysis to determine whether the use of distal protection devices during revascularization can improve myocardial perfusion and reduce the occurrence of MACEs compared with primary percutaneous coronary intervention (PCI) alone.

METHODS AND RESULTS

Studies were identified in English-language articles by search of Medline and Embase database (inception to December 2011). A total of 15 prospective randomized controlled trials involving 2783 patients were included for analysis (1378 patients in the distal protection device group and 1405 cases in the control group). Overall, adjunctive embolic protection was associated with significantly improved postprocedural TIMI 3 (thrombolysis in myocardial infarction 3) flow (OR 1.71; 95% CI 1.13-2.57; P = 0.01) and MBG 3 (myocardial blush grade 3) (OR 1.50; 95% CI 1.09-2.07; P = 0.01), whereas the overall MACEs analysis demonstrated that a nonsignificant trend was observed toward better clinical outcomes associated with adjunctive protection devices at 1 month (OR 0.80; 95% CI 0.55-1.15; P = 0.23) and at 6 months (OR 0.80; 95% CI 0.55-1.17; P = 0.24). When stratified by MACEs, no statistical differences were found among mortality, reinfarction, and target vessel revascularization (TVR), respectively.

CONCLUSIONS

The meta-analysis indicated an improvement of myocardial perfusion in AMI patients treated with adjunctive protection devices. However, a nonsignificant trend was observed toward a lower risk of MACEs in the distal protection device group when compared with the control group.

Saphenous vein graft intervention

Saphenous vein grafts are commonly used conduits for surgical revascularization of coronary arteries but are associated with poor long-term patency rates. Percutaneous revascularization of saphenous vein grafts is associated with worse clinical outcomes including higher rates of in-stent restenosis, target vessel revascularization, myocardial infarction, and death compared with percutaneous coronary intervention of native coronary arteries. Use of embolic protection devices is a Class I indication according to the American College of Cardiology/American Heart Association guidelines to decrease the risk of distal embolization, no-reflow, and periprocedural myocardial infarction. Nonetheless, these devices are underused in clinical practice. Various pharmacological agents are available that may also reduce the risk of or mitigate the consequences of no-reflow. Covered stents do not decrease the rates of periprocedural myocardial infarction and restenosis. Most available evidence supports treatment with drug-eluting stents in this high-risk lesion subset to reduce angiographic and clinical restenosis, although large, randomized trials comparing drug-eluting stents and bare-metal stents are needed.

Management of the no-reflow phenomenon

The lack of reperfusion of myocardium after prolonged ischaemia that may occur despite opening of the infarct-related artery is termed "no reflow". No reflow or slow flow occurs in 3-4% of all percutaneous coronary interventions, and is most common after emergency revascularization for acute myocardial infarction. In this setting no reflow is reported to occur in 30% to 40% of interventions when defined by myocardial perfusion techniques such as myocardial contrast echocardiography. No reflow is clinically important as it is independently associated with increased occurrence of malignant arrhythmias, cardiac failure, as well as in-hospital and long-term mortality. Previously the no-reflow phenomenon has been difficult to treat effectively, but recent advances in the understanding of the pathophysiology of no reflow have led to several novel treatment strategies. These include prophylactic use of vasodilator therapies, mechanical devices, ischaemic postconditioning and potent platelet inhibitors. As no reflow is a multifactorial process, a combination of these treatments is more likely to be effective than any of these alone. In this review we discuss the pathophysiology of no reflow and present the numerous recent advances in therapy for this important clinical problem.

Embolic protection device use in renal artery stent placement

PURPOSE

The purpose of the present study was to report safety, efficacy, and renal function outcomes with use of the GuardWire embolic protection device (EPD) in renal artery stent placement for patients with renal artery stenosis (RAS) and chronic renal insufficiency (CRI).

MATERIALS AND METHODS

This was a retrospective study of all patients with RAS and CRI treated concomitantly with a GuardWire EPD and renal artery stents from December 2002 through June 2006. Renal function was determined by calculating the estimated glomerular filtration rate (eGFR) according to the Modification of Diet in Renal Disease formula, and subjects were divided into Kidney Disease Outcomes and Quality Initiative (K-DOQI) classes based on baseline eGFR. After revascularization, an improvement from baseline of at least one K-DOQI class was defined as improvement, unchanged K-DOQI class as stabilization, and worsening of at least one K-DOQI class as deterioration.

RESULTS

There were 63 patients (54% men) with a mean age of 75.2 years +/- 7.7. The mean baseline serum creatinine level and eGFR were 1.87 mg/dL +/- 0.6 (range, 1-3.8 mg/dL) and 36.63 mL/min per 1.73 m(2) +/- 11.42 (range, 13.85-59.99 mL/min per 1.73 m(2)), respectively, and at the last clinical follow-up, the respective measurements were 1.96 mg/dL +/- 0.72 and 38.75 mL/min per 1.73 m(2) +/- 13.25 (P = not significant). Over a mean follow-up period of 16 months +/- 12, 14 patients (25%) showed improvement, 33 (58%) had stable renal function, and 10 (18%) showed deterioration. There was one GuardWire-related dissection, which was successfully treated with a stent.

CONCLUSIONS

The GuardWire EPD, used during renal artery stent placement, is safe and was associated with stabilization or improvement in kidney function in 83% of patients with RAS and CRI.

Catheter-Based Treatment of Coronary Artery Disease

September 2007 marked the 30-year anniversary of the first human percutaneous coronary intervention, an index event that changed the course of modern-day cardiovascular care. Before that first procedure, adult invasive cardiology focused on diagnostic angiography as well as hemodynamic assessment of structural heart disease. Since that initial procedure, percutaneous coronary intervention has become the most frequently performed coronary revascularization procedure worldwide. Several factors have been responsible for this dramatic paradigm shift, the most prominent being identification of opportunities for technical improvement and the application of innovation and investigation in concert with colleagues, professional societies, and industry. These approaches will continue to be of paramount importance as new technologies are brought to bear on an increasingly broader group of patients with cardiovascular disease.

Time-dependent benefit of initial thrombosuction on myocardial reperfusion in primary percutaneous coronary intervention

BACKGROUND

In ST-segment elevation acute myocardial infarction (STEMI), dislodgement of thrombus within the culprit artery during primary percutaneous coronary intervention (PCI) may cause distal embolisation and impaired myocardial reperfusion. Clinical results of thromboembolic protection strategies have been controversial. We conducted this study to investigate whether the benefit of thrombus removal is time dependent.

METHODS

Seventy-four STEMI patients within 12 h from onset were randomised to receive either primary PCI with initial thrombosuction (IT) or standard strategy. Results were analysed in subgroups according to the onset-to-lab time intervals (subgroup 1: 0-240 min, subgroup 2: 241-480 min and subgroup 3: 481-720 min).

RESULTS

The primary end-points were improvements in thrombolysis in myocardial infarction flow (DeltaTIMI) and myocardial blush grade (DeltaMBG) postprocedure. Better DeltaTIMI (2.2 +/- 1.1 vs. 1.5 +/- 1.3, p = 0.014) and DeltaMBG (2.3 +/- 1.1 vs. 1.0 +/- 1.5, p < 0.001) were observed in IT patients, compared with standard PCI patients. In onset-to-lab time subgroup analysis, the difference between IT and standard PCI is significant only in subgroup 2 (DeltaTIMI 2.6 +/- 1.0 vs. 1.3 +/- 1.2, p = 0.007; DeltaMBG 2.6 +/- 0.9 vs. 1.0 +/- 1.1, p = 0.010), but not in the other two subgroups.

CONCLUSIONS

This prospective randomised study shows that primary PCI with IT may improve epicardial flow and myocardial reperfusion in patients with STEMI, and this benefit is the most significant in patients treated within 4-8 h after symptom onset.

Saphenous Vein Graft Stenting and Major Adverse Cardiac Events

Background— Treatment of saphenous vein graft (SVG) stenosis with percutaneous coronary intervention has a 15% to 20% incidence of major adverse cardiac events (MACE) within 30 days. Although MACE rates are reduced significantly by the use of embolic protection devices (EPDs), neither the level of baseline risk nor the benefit provided by EPDs has been well characterized.

Methods and Results— Data from 5 randomized controlled trials and 1 registry evaluating EPDs in SVG percutaneous coronary intervention (n=3958 patients) were pooled for analysis. MACE was defined as a composite of death, myocardial infarction, and target vessel revascularization. Baseline variables and 2 summary angiographic variables (an SVG degeneration score and an estimate of lesion plaque volume) were included in a multivariable logistic regression model to predict 30-day MACE, with adjustment for the type of device used and inter-study variation. The angiographic variables were potent predictors of MACE (increasing SVG degeneration score, P <0.0001; larger estimated plaque volume, P <0.0001), with significant contributions from the presence of thrombus ( P <0.01), increasing patient age ( P <0.01), glycoprotein IIb/IIIa inhibitor use ( P =0.02), and current tobacco abuse ( P =0.03). The treatment benefit of EPDs was preserved across all categories of risk as categorized by SVG degeneration or plaque volume.

Conclusions— The strongest predictors of 30-day MACE in SVG percutaneous coronary intervention are angiographic estimates of plaque volume and SVG degeneration. Identification of these predictors of 30-day MACE allows reliable prediction of patient outcomes and confirms consistent treatment benefit with the use of EPDs across the range of patients tested in randomized trials.

CT Angiography of Renal Artery Anatomy for Evaluating Embolic Protection Devices

PURPOSE

To determine which commercially available embolic protection devices are suitable for use in renal arteries.

MATERIAL AND METHODS

A retrospective study was conducted of 97 patients who underwent three-dimensional computed tomographic (CT) angiography with either 16- or 64-detector row helical CT of the renal arteries for the evaluation of renal artery stenosis. Nine anatomic measurements were obtained of the renal artery from each reformatted CT angiogram. These data were used to evaluate seven commercially available embolic protection devices (SpideRX, BSC FilterWire EZ, GuardWire, Angioguard, Accunet, Emboshield, TriActiv FX) to determine suitability for use in conjunction with renal artery stent placement. The authors evaluated the reference vessel diameter (diameter to which the stent would be expanded) and length of device.

RESULTS

The mean length (+/- standard deviation) of the main renal artery on the left (39.9 mm +/- 6.7) was significantly less than that on the right (44.9 mm +/- 7.4, P < .001). The mean distal diameter of the main renal artery was significantly larger on the left (6.0 mm +/- 0.5) than on the right (5.6 mm +/- 0.6, P = .02). For a reference vessel diameter of 4-7 mm necessitating a 12-mm-long stent, only three of the seven devices tested (SpideRx, Angioguard, and Accunet) could be used.

CONCLUSION

Three of the seven devices tested could be used for reference vessel diameters of 4-7 mm necessitating a 12-mm-long stent.

Safety and efficacy of the FilterWire EZ in acute ST-segment elevation myocardial infarction

Primary percutaneous coronary intervention (PCI) for ST-segment elevation myocardial infarction (STEMI) achieves a high epicardial reperfusion rate; however, it is often suboptimal in achieving myocardial reperfusion due to distal embolization of atherothrombotic particles. The present study assessed whether the capture of embolic particles during PCI would improve myocardial reperfusion outcome. In a multicenter, prospective, randomized, controlled study, 100 patients with STEMI and coronary angiographic evidence of thrombotic occlusion were randomly assigned to PCI using the FilterWire EZ (n=51) or a control group (n=49) using regular guidewires. The FilterWire EZ was successfully delivered across the lesion in 84% of patients in the FilterWire EZ group. Primary efficacy end points, including markers of epicardial (Thrombolysis In Myocardial Infarction grade flow) and myocardial reperfusion (myocardial blush score and percent early resolution of ST-segment elevation), did not differ between the 2 study groups. Further, 60- and 90-minute percent ST-segment resolutions were identical in the 2 groups. In a subgroup analysis, a blush score of 3 was achieved in 94% of patients in whom the filter's landing zone was in a vessel diameter>2.5 mm compared with only 55% in those with smaller vessel diameter (p=0.04). This corresponds to a better debris capture in filters located in large versus small vessels (p=0.08). In conclusion, in patients with STEMI, use of the FilterWire EZ as an adjunct to primary PCI did not improve angiographic or electrocardiographic measurements of reperfusion compared with conventional PCI only.

Percutaneous Saphenous Vein Graft Intervention—A Review

Re-do coronary artery bypass graft (CABG) surgery carries significant risk to the patient and existing patent internal thoracic artery grafts. Stenting stenotic saphenous vein grafts (SVGs) with drug-eluting stents (DES) using embolic protection devices (EPDs) is therefore probably the optimum treatment. However, this is fraught with challenges such as distal embolisation and restenosis which may result in peri-procedural myocardial infarction and target vessel failure, respectively. This review focuses on the nature of SVG disease, percutaneous intervention utilising embolic protection and future directions aimed at combating the disappointingly high procedural complication rate and long-term recurrence in this group.

Revascularization in atherosclerotic renovascular disease: Problems beyond the obstruction

The main goal in the treatment of obstructive atherosclerotic renovascular disease (ARVD) is to preserve or recover renal function. The ARVD kidney continues to deteriorate in 20-40% of cases despite restoration of blood flow. Holden et al. report that renal function stabilized or improved in up to 97% of patients with the use of a distal embolic protection device.