Distal Myocardial Protection During Percutaneous Coronary Intervention

Microvascular coronary flow comparison in acute myocardial infarction angioplasty treated with a mesh covered stent (MGUARD stent) versus bare metal stent: MICAMI-MGUARD

BACKGROUND

Distal embolization of thrombus/platelet aggregates decreases myocardial reperfusion during primary percutaneous coronary intervention (PCI), and is associated with worse immediate and long-term prognosis of patients with ST-elevation myocardial infarction (STEMI).

OBJECTIVE

Assess the efficacy of a mesh covered stent (MGuard™ stent, MGS) in preventing distal embolization and microvascular reperfusion impairment during primary PCI, compared with a bare metal stent (BMS).

METHODS

Forty patients with STEMI referred for primary PCI were randomized for stenting the culprit lesion with the MGS (n = 20) or a BMS (n = 20). Blinded experts performed off-line measurements of angiographic epicardial and microvascular reperfusion criteria: TIMI flow grade, myocardial blush, corrected TIMI frame count (cTFC).

RESULTS

At baseline clinical, angiographic and procedural variables were not different between groups. Post PCI TIMI flow grade was similar in both groups. We observed better myocardial Blush grade in group MGS compared to BMS (median value 3.0 vs 2.5, 2p = 0.006) and cTFC (mean cTFC: MGS 19.65 ± 4.07 vs BMS 27.35 ± 7.15, 2p < 0.001, cTFC mean difference MGS-BMS: 7.7, CI 95%: 3.94 to 11.46). MGS stent group had a higher percentage of successful angioplasty (cTFC ≤ 23: MGS 85% vs BMS 30%, 2p < 0.001). We had two cases of acute stent thrombosis (one for each group) at 30days follow up, but no clinical events at 6 months follow up.

CONCLUSIONS

In this exploratory study, MGS significantly improved microvascular reperfusion criteria compared with a BMS in primary PCI. However its safety and impact on clinical outcomes should be verified in larger randomized clinical trials.

Embolic Protection Devices for Saphenous Vein Graft Percutaneous Coronary Interventions

Saphenous vein graft (SVG) percutaneous coronary interventions (PCIs) are associated with adverse clinical events caused by distal embolization in 10% to 20% of cases. Various embolic protection devices (EPDs) have been developed to lower the risk of distal embolization during SVG PCI: distal balloon occlusive devices, distal embolic filters, and proximal balloon occlusive devices. Despite evidence for improved outcomes and cost-effectiveness, rates of national EPD use remain low, the main cause of underutilization being operator preference. With increasing familiarity of operators with EPDs, their use should continue to increase in SVG PCI and lead to better outcomes.

Management of Complications During Saphenous Vein Graft Interventions

Because of greater patient comorbidities, more diffusely diseased vessels, and the greater possibility of mechanical complications, saphenous vein graft interventions are fraught with complications. The greatest risk is a higher risk of periprocedural myocardial infarction due to distal embolization of microemboli. The risk for noreflow in a patient with concomitant native critical vessel disease can have grave consequences. Minimizing the risk of periprocedural myocardial infarction with the use of distal embolic protection, understanding the role of adjunctive pharmacotherapy, and learning how to manage less common but serious mechanical complications during saphenous vein graft interventions are important to ensure optimal patient outcomes.

Contemporary incidence and predictors of major adverse cardiac events after saphenous vein graft intervention with embolic protection (an AMEthyst trial substudy)

The incidence and predictors of major adverse cardiac events after percutaneous coronary intervention of saphenous vein grafts have not been evaluated in the era of routine embolic protection device (EPD) use and the current standards of antiplatelet therapy. The Assessment of the Medtronic AVE Interceptor Saphenous Vein Graft Filter System (AMEthyst) is the largest randomized trial of vein graft intervention comparing the Interceptor EPD and either the GuardWire or FilterWire EPD as the control. The baseline demographic, procedural, and clinical characteristics and the 30-day major adverse cardiac events ([MACE] death, myocardial infarction, and repeat revascularization [either surgery or percutaneous coronary intervention] of the target vessel) were recorded for 748 patients who had undergone vein graft intervention with distal embolic protection. At 30 days, MACE had occurred in 58 patients (7.8%). The univariate predictors of MACE at 30 days included plaque volume (odds ratio 1.005/mm(3), p <0.0001), target lesion length (odds ratio 1.046/mm, p <0.001), vein graft degeneration score (odds ratio 1.631, p = 0.001), coronary narrowing classification (odds ratio 1.697, p = 0.004), reference vessel diameter (odds ratio 1.689, p = 0.004), and male gender (odds ratio 2.406, p = 0.046) and was independent of device type (p = 0.74). The plaque volume was the most important and only multivariate predictor of MACE. The highest quartile of plaque volume defined a subset at particular risk, despite EPD use (MACE 15.8% vs 5.0%, p <0.001). In conclusion, in a patient population in which EPD and preprocedure thienopyridine therapy were uniformly implemented, MACE occurred with an incidence of 7.8% at 30 days. An increasing plaque volume was the most important determinant of MACE and defined a population at particular risk.

Multicentre experience with MGuard net protective stent in ST-elevation myocardial infarction: safety, feasibility, and impact on myocardial reperfusion

OBJECTIVE

To report, for the first time, angiographic and ECG results as well as in-hospital and 1-month clinical follow-up, after MGuard net protective stent (Inspire-MD, Tel-Aviv, Israel-MGS) implantation in consecutive, not randomized, STEMI patients undergoing primary or rescue PCI.

BACKGROUND

Distal embolization may decrease coronary and myocardial reperfusion after percutaneous coronary intervention (PCI), in ST-elevation myocardial infarction (STEMI) setting.

METHODS

One-hundred consecutive patients underwent PCI, with MGS deployment for STEMI, in five different high-volume PCI centres. Sixteen patients presented cardiogenic shock at admission.

RESULTS

All patients underwent successful procedures: mean TIMI flow grade and mean corrected TIMI frame count-cTFC(n)-improved from baseline values to 2.85 +/- 0.40 and to 17.20 +/- 10.51, respectively, with a mean difference in cTFC(n) between baseline and postprocedure of 46.88 +/- 31.86. High-myocardial blush grade (90% MBG 3; 10% MBG 2) was also achieved in all patients. Sixty minutes post-PCI, a high rate (90%) of complete (>or=70%) ST-segment resolution was achieved. At in-hospital follow-up, seven deaths occurred: noteworthy, 5 of 16 patients with cardiogenic shock at admission died. After hospital discharge, no Major Adverse Cardiac Events have been reported up to 30-day follow-up.

CONCLUSIONS

MGS might represent a safe and feasible option for PCI in STEMI patients, providing high perfusional and ECG improvement. Further randomized trials comparing this strategy with the conventional one are needed in the near future to assess the impact on clinical practice of this strategy.

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.

The role of distal myocardial protection devices during percutaneous coronary interventions

The success of intervention and clinical outcome is markedly reduced in patients who sustain distal embolization during percutaneous coronary intervention (PCI). Such embolization occurs in up to 15% of patients with acute myocardial infarction (AMI) undergoing PCI, and angiographic indicators of embolization are highly predictive of clinical and functional outcome. Saphenous vein graft (SVG) interventions carry a 20% risk of major adverse cardiac events (MACE), predominantly AMI, and significant risk of no-reflow. There are four types of embolic protection: distal occlusion/aspiration systems, filters, proximal occlusion/aspiration devices, and thrombectomy catheters. There seem to be no data to suggest that routine use of any embolic protection system is beneficial in patients with ST-elevation myocardial infarction (STEMI) undergoing PCI. The message from both the EMERALD and PROMISE trials is that embolic protection does not improve perfusion in the setting of AMI. Although pretreatment with thrombus aspiration before PCI improves angiographic reperfusion rates compared with standard PCI, enzymatic release and early clinical outcomes are not improved. Although the clinical implications of routine thrombus aspiration have yet to be established, selective use may be justified in patients with the highest thrombus burden. In addition, it should be considered in those with acute stent thrombosis and elective use of filter-based protection considered in very high risk vessel PCI (eg, last remaining conduit). There is no easy way to anticipate which SVG intervention will result in embolization. In SVG intervention, both balloon occlusion/aspiration and filter-based distal protection devices have significantly reduced the incidence of 30-day MACE, driven by AMI and should, I believe, be used routinely. Risk of complications is low with all the established devices. The profile and deliverability are continuing to improve with newer devices. Cost-effectiveness of selective use in high-risk graft cases has only recently been demonstrated.

Distal embolic protection during percutaneous intervention of aorto-coronary venous bypass grafts: The FIRST Trial

OBJECTIVE

Interventions in aorto-coronary venous bypass grafts (CABG) can cause acute procedural complications due to distal embolization of debris. In the FIRST (First European Investigation Regarding the Systematic use of the TriActiv device) multicenter trial the distal endovascular protection system TriActiv (Kensey Nash) was evaluated during intervention of CABG.

METHODS

195 patients in 17 centers in Germany with significant disease of a vein graft were enrolled. Inclusion and exclusion criteria were comparable to the SAFER trial.

RESULTS

Acute procedural success was achieved in 98% of cases. Aspirated debris was found in 96.5% of patients. Primary endpoints (MACE at 30 days) occurred in 8.7% of all pts. (ITT). No patient died and 7.2% of patients suffered from MI. The rate of early revascularization was 1.5%. Secondary endpoints (MACCE at 30 days) were found in 9.2% and at hospital discharge in 8.7% of patients.

CONCLUSIONS

The TriActiv system is safe and effective. Normal post procedural flow can be preserved and the MACE rate is with 8.7% considerably low. The FIRST trial supports the growing belief that PCI of CABG should be performed with protection systems.

Imaging microvascular obstruction and its clinical significance following acute myocardial infarction

Obstruction of the coronary microvasculature contributes to the pathophysiology of MI and adversely affects post-MI recovery. This "no-reflow" phenomenon resulting from microvascular obstruction is an indicator of lack of adequate tissue perfusion within the infarcted myocardium, even after restoration of epicardial blood flow. Regions of microvascular obstruction can be detected and quantifed because of rapid advances in and refinement of imaging technologies over the past decade. This article focuses on the non-invasive imaging modalities used to assess MO, discusses the prognostic implications of MO, and briefly addresses strategies for reducing MO.

Risk-adjusted mortality analysis of percutaneous coronary interventions by American College of Cardiology/American Heart Association guidelines recommendations

An American College of Cardiology (ACC)/American Heart Association (AHA) task force on practice guidelines in 2001 published evidence-based recommendations for performing percutaneous coronary interventions (PCIs). These guidelines grouped the indications for PCI into 4 classes (I, IIa, IIb, and III) based on analyses of risks and benefits. In a previous study, we found that clinical success and in-hospital adverse events varied by indications class. However, no adjustment for risk was used in those comparisons. The ACC/National Cardiovascular Data Registry (ACC-NCDR) previously developed a risk-adjustment model for the adverse event of in-hospital PCI mortality. We investigated how the 14 individual risk factors in the ACC-NCDR PCI mortality model might differ across the 4 indications classes and whether estimated mortality for each class approximated the observed mortality for that class. We analyzed the ACC-NCDR PCI database for January 1, 2001 to December 31, 2004. We excluded procedures performed for treatment of acute ST-segment elevation myocardial infarction; all others were included, yielding 559,273 procedures for analysis. An algorithm derived from the 2001 guidelines was used to assign procedures to an indications class. Increasing frequencies of risk components were observed across classes I, IIa, IIb, and III. Expected mortalities for each class calculated by the risk-adjustment model were close to observed values (expected 0.52%, 0.59%, 1.72%, and 1.96%, respectively; observed 0.49%, 0.63%, 1.88%, and 1.60%, respectively). In conclusion, the ACC-NCDR risk-adjusted mortality model can be linked to the ACC/AHA PCI guidelines, and together these produce mortality risk estimates by indications classes that are close to actual observed values. With further refinement, these methods should be able to be used as powerful analytic tools for quality assurance and appropriateness purposes.

Thrombus predicts ischemic complications during percutaneous coronary intervention in saphenous vein grafts: Results from TARGET (do tirofiban and reopro give similar efficacy trial?)

BACKGROUND

Saphenous vein graft (SVG) percutaneous coronary intervention (PCI) carries a high risk of ischemic complications. However, there are scant recent data to identify which SVG lesions carry particularly high risk in recent years. We studied demographic and angiographic factors associated with ischemic complications after SVG PCI without distal protection in the TARGET (do tirofiban and reopro give similar efficacy trial?) study.

METHODS

TARGET was a multicenter double-dummy, double-blinded study randomizing 4,809 PCI patients to tirofiban or abciximab. Of these, 254 patients underwent PCI involving an SVG lesion. The primary endpoint of this analysis was major adverse cardiac events (MACEs) at 30 days, including death, nonfatal myocardial infarction (MI), and urgent target vessel revascularization.

RESULTS

No demographic characteristic was associated with 30-day MACE. Lesion length > 20 mm (odds ratio [OR] = 2.7, P = 0.03), thrombus (OR = 3.9, P = 0.003), eccentricity (P = 0.001), thrombolysis in myocardial infarction flow < 3 post-procedure (OR = 5.6, P = 0.037), and >1 target lesion (OR = 2.5, P = 0.035) were univariate variables associated with 30-day MACE. Multivariate analysis associated only thrombus (OR = 3.8, P = 0.015) with 30-day MACE. No difference in outcomes was noted between patients receiving abciximab and tirofiban. SVG patients had lesser angiographic success (95.6% vs. 98%, P = 0.04) and increased 30-day Q-wave MI (2.5% vs. 0.9%, P = 0.039) compared with non-SVG patients, but a similar incidence of death (0% vs. 0.4%), non-Q-MI (5.9% vs. 4.5%), and target vessel revascularization (0.5% vs. 1%).

CONCLUSION

In the era of routine stenting and GpIIb/IIIa inhibitors, thrombus is the angiographic characteristic most closely associated with adverse outcomes of SVG PCI.

Distal protection in cardiovascular medicine: current status

Iatrogenic and spontaneous downstream microembolization of atheromatous material is increasingly recognized as a source of cardiovascular morbidity and mortality. Devising ways of reducing this distal embolization using a variety of mechanical means--distal protection--is currently under intense and diverse investigation. This review therefore summarizes the present status of distal protection. It examines the problem of distal embolization, describes the available distal protection devices, reviews those areas of cardiovascular medicine where distal protection devices are being investigated, and discusses potential future developments.

Mechanical thrombectomy options in complex percutaneous coronary interventions

Percutaneous coronary interventions (PCI) of thrombus-containing lesions are associated with an increased risk of acute complications and poorer long term vessel patency. Dealing with these vessels provides many technical challenges, especially with the significant risk of coronary no reflow and distal embolization. Pharmacological strategies, including intravenous and intracoronary glycoprotein IIbIIIa inhibitors reduce intracoronary thrombus propagation, improve TIMI flow and are associated with a reduction in adverse event rates. Mechanical strategies (particularly embolic protection and thrombectomy catheters) help to improve coronary blood flow and myocardial perfusion. However, their impact on clinical outcomes is less clear. The use of embolic protection devices is associated with better perfusion, blood flow, and clinical outcomes among patients undergoing saphenous vein graft (SVG) PCI. However, the role for these devices in primary PCI and native coronary artery interventions is uncertain. This study examines the current approaches to manage thrombotic lesions during PCI and reviews the evidence in support of the different mechanical thrombectomy options that are available to the interventional cardiologist.