Beneficial effects of intracoronary adenosine as an adjunct to primary angioplasty in acute myocardial infarction

Exogenous adenosine triphosphate disodium administration during primary percutaneous coronary intervention reduces no-reflow and preserves left ventricular function in patients with acute anterior myocardial infarction: a study using myocardial contrast echocardiography

BACKGROUND

It is unknown whether adenosine triphosphate disodium (ATP) administration during primary percutaneous coronary intervention (PCI) is useful in anterior acute myocardial infarction (AMI).

METHODS

The study was a prospective, non-randomized, open-label trial. Primary PCI was successfully performed in 204 consecutive patients with first anterior AMI. ATP at a mean dose of 117 microg/kg/min for 45 min on an average was infused intravenously during PCI in 100 patients (Group 1). In the other 104 patients, normal saline was administered (Group 2). ST-segment resolution (STR) was estimated 90 min after recanalization. The no-reflow ratio was measured 2 weeks later, using intravenous myocardial contrast echocardiography. Left ventricular ejection fraction (LVEF), LV regional wall motion (LVRWM), and LV end-diastolic volume index (LVEDVI) were measured 6 months later.

RESULTS

Baseline patient characteristics of the two groups were similar, including TIMI risk scores. Significant STR (> or =50% resolution compared to baseline) (66% versus 50%; Group 1 versus Group 2, p=0.02), no-reflow ratio (24% versus 34%, indicated by mean values, p=0.02), LVEF (61% versus 55%, p=0.0007), LVRWM (-1.56 versus -2.05, using the SD/chord, p=0.0001), and LVEDVI (60 ml/m(2) versus 71 ml/m(2), p=0.0007) were significantly better in Group 1, and the no-reflow ratio, LVEF, LVRWM and LVEDVI were significantly better in ATP-administered patients, regardless of antecedent angina or advanced age. ATP Administration was consistently identified as a significant determinant for STR, no-reflow ratio, LVEF, LVRWM, and LVEDVI.

CONCLUSIONS

Intravenous ATP administration during reperfusion is an independent determinant of STR and the no-reflow ratio, and LVEF, LVRWM, and LVEDVI at 6 months after primary PCI.

Acadesine, an adenosine-regulating agent with the potential for widespread indications

BACKGROUND

Acadesine is an adenosine-regulating agent that increases bioavailability of adenosine and has important metabolic effects, partly through activation of the key metabolic regulatory enzyme, AMP-activated protein kinase.

OBJECTIVE

This review aimed to summarise and critique available data on the mechanism of action and clinical utility of acadesine, with a focus on treatment of ischaemic reperfusion injury, B-cell chronic lymphocytic leukaemia and diabetes mellitus.

METHODS

The literature was acquired through numerous avenues including Medline, Pubmed, institutional libraries and relevant pharmaceutical companies using keyword search criteria for all trade and common names of acadesine and its derivatives.

RESULTS

Acadesine has proven intravenous efficacy in the amelioration of ischaemic reperfusion injury associated with coronary artery bypass graft surgery in Phase III clinical trials. Acadesine is active only in metabolically stressed tissues in the presence of ATP catabolism and therefore has fewer unwanted peripheral side effects than systemic administration of adenosine. Metabolism of the drug is through the endogenous purine pathway and acadesine has been proven to be safe and well tolerated. More recently, acadesine has entered Phase I trials for B-cell chronic lymphocytic leukaemia to compete with purine antagonists that are used at present. AMPK-activating agents with high oral bioavailability have potential application in impaired glucose tolerance, insulin resistance and types 1 and 2 diabetes, however the poor oral bioavailability of acadesine precludes such application.

CONCLUSIONS

This review highlights that, although limited to intravenous application, acadesine is a potentially viable therapy for ischaemic reperfusion injury following coronary artery bypass surgery. Further studies are required to determine the efficacy of acadesine for other ischaemic indications, including during percutaneous transluminal coronary angioplasty for acute myocardial infarction.

Intracoronary Vasodilators for the No-Reflow Phenomenon

Objective:

To review the literature relating to the use of intracoronary vasodilators to prevent and/or treat the no-reflow phenomenon in patients undergoing percutaneous coronary intervention (PCI).

Data Sources:

A literature search was conducted using MEDLINE (1966–March 2008) and Science Citation Index (1945–March 2008) using the search terms vasodilators, no-reflow, and intracoronary.

Study Selection and Data Extraction:

English-language clinical trials and case series were selected from articles retrieved. References of reviewed articles were examined for additional sources. Studies relating to the use of intracoronary vasodilators in the prevention and/or treatment of no-reflow in PCI were evaluated for safety and efficacy data. Articles relating to agents not available in the US were excluded.

Data Synthesis:

Evidence of intracoronary adenosine's utility in no-reflow treatment is limited. Its use in no-reflow prevention was associated with outcomes ranging from no difference to nearly an 88% reduction in no-reflow development; the drug was generally well tolerated. No-reflow treatment with intracoronary verapamil improved flow in 87–100% of cases. Preventive trials with verapamil failed to demonstrate efficacy. Atrioventricular block requiring treatment was the most commonly reported adverse event with intracoronary verapamil. Literature on intracoronary diltiazem and intracoronary nicardipine is limited. Both agents produced greater than 95% efficacy in no-reflow treatment, while prevention studies found no-reflow developing in less than 4% of patients. Although adverse event reporting was limited, hemodynamic instability was noted in patients receiving diltiazem. Response rates ranged from 73% to 100% when intracoronary nitroprusside was studied as treatment for no-reflow associated with acute myocardial infarction (AMI). Systemic hypotension was noted with nitroprusside administration.

Conclusions:

The available data are predominately from case series and retrospective reviews. Prevention of no-reflow with intracoronary vasodilators in elective PCI is not warranted. Nitroprusside should be considered first-line treatment in no-reflow associated with AMI.

The diagnostic accuracy of pharmacological stress echocardiography for the assessment of coronary artery disease: a meta-analysis

BACKGROUND

Recent American Heart Association/American College of Cardiology guidelines state that "dobutamine stress echo has substantially higher sensitivity than vasodilator stress echo for detection of coronary artery stenosis" while the European Society of Cardiology guidelines and the European Association of Echocardiography recommendations conclude that "the two tests have very similar applications". Who is right?

AIM

To evaluate the diagnostic accuracy of dobutamine versus dipyridamole stress echocardiography through an evidence-based approach.

METHODS

From PubMed search, we identified all papers with coronary angiographic verification and head-to-head comparison of dobutamine stress echo (40 mcg/kg/min +/- atropine) versus dipyridamole stress echo performed with state-of-the art protocols (either 0.84 mg/kg in 10' plus atropine, or 0.84 mg/kg in 6' without atropine). A total of 5 papers have been found. Pooled weight meta-analysis was performed.

RESULTS

the 5 analyzed papers recruited 435 patients, 299 with and 136 without angiographically assessed coronary artery disease (quantitatively assessed stenosis > 50%). Dipyridamole and dobutamine showed similar accuracy (87%, 95% confidence intervals, CI, 83-90, vs. 84%, CI, 80-88, p = 0.48), sensitivity (85%, CI 80-89, vs. 86%, CI 78-91, p = 0.81) and specificity (89%, CI 82-94 vs. 86%, CI 75-89, p = 0.15).

CONCLUSION

When state-of-the art protocols are considered, dipyridamole and dobutamine stress echo have similar accuracy, specificity and - most importantly - sensitivity for detection of CAD. European recommendations concluding that "dobutamine and vasodilators (at appropriately high doses) are equally potent ischemic stressors for inducing wall motion abnormalities in presence of a critical coronary artery stenosis" are evidence-based.

Use of the TIMI frame count in the assessment of coronary artery blood flow and microvascular function over the past 15 years

Since its introduction, the TIMI frame count method has contributed to the understanding of the pathophysiology of coronary artery disease. In this article, the evolution of the TFC method and its applicability in the assessment of various therapeutic modalities are described.

Relation of corrected thrombolysis in myocardial infarction frame count and ST-segment resolution to myocardial tissue perfusion after acute myocardial infarction

OBJECTIVES

To evaluate myocardial tissue perfusion by corrected thrombolysis in myocardial infarction (TIMI) frame count (CTFC) and ST-segment resolution after successful percutaneous coronary intervention (PCI) in patients with acute myocardial infarction (AMI).

BACKGROUND

Early and sustained potency of infarct-related artery (IRA) has become the main goal of reperfusion therapy in patients with AMI. However, myocardial tissue perfusion may remain impaired even after the achievement of TIMI grade 3 flow of the epicardial artery without residual stenosis.

METHODS

CTFC was measured after successful PCI in 63 patients with first AMI. The extent of ST-segment resolution was recorded 1 hr after reperfusion therapy. The wall motion score index (WMSI) was assessed before and 1 month after PCI. Then we studied the correlation between CTFC, ST-segment resolution, and WMSI.

RESULTS

According to CTFC, the patients with TIMI grade 3 flow after PCI were divided into two groups: CTFC fast group and CTFC slow group. CTFC fast group had higher percentage of complete ST resolution (54.1% vs. 25.0%, P < 0.05) and lower percentage of no ST resolution (2.6% vs. 29.2%, P < 0.05). Improvement of WMSI in the CTFC fast group was significantly greater than that of the CTFC slow group (1.30 +/- 0.41 vs. 0.64 +/- 0.30, P < 0.05). CTFC had a significant negative correlation with the change in WMSI (r = -0.75, P < 0.01).

CONCLUSIONS

Combined with ST-segment resolution, CTFC could predict risk for patients with successful reperfusion therapy after AMI and provide evidence for additional adjunctive treatment.

Adenosine receptor-mediated adhesion of endothelial progenitors to cardiac microvascular endothelial cells

Intracoronary delivery of endothelial progenitor cells (EPCs) is an emerging concept for the treatment of cardiovascular disease. Enhancement of EPC adhesion to vascular endothelium could improve cell retention within targeted organs. Because extracellular adenosine is elevated at sites of ischemia and stimulates neovascularization, we examined the potential role of adenosine in augmenting EPC retention to cardiac microvascular endothelium. Stimulation of adenosine receptors in murine embryonic EPCs (eEPCs) and cardiac endothelial cells (cECs) rapidly, within minutes, increased eEPC adhesion to cECs under static and flow conditions. Similarly, adhesion of human adult culture-expanded EPCs to human cECs was increased by stimulation of adenosine receptors. Furthermore, adenosine increased eEPC retention in isolated mouse hearts perfused with eEPCs. We determined that eEPCs and cECs preferentially express functional A1 and A2B adenosine receptor subtypes, respectively, and that both subtypes are involved in the regulation of eEPC adhesion to cECs. We documented that the interaction between P-selectin and its ligand (P-selectin glycoprotein ligand-1) plays a role in adenosine-dependent eEPC adhesion to cECs and that stimulation of adenosine receptors in cECs induces rapid cell surface expression of P-selectin. Our results suggest a role for adenosine in vasculogenesis and its potential use to stimulate engraftment in cell-based therapies.

Surgery for myocardial salvage in acute myocardial infarction and acute coronary syndromes

This article addresses the pathophysiology, the treatment options, and their rationale in the setting of life-threatening acute myocardial infarction and acute on chronic ischemia. Although biases may exist between cardiologists and surgeons, with this review, we hope to provide the reader with information that will shed light on the options that best suit the individual patient in a given set of circumstances.

Percutaneous coronary intervention and the no-reflow phenomenon

No-reflow during percutaneous coronary intervention (PCI) is observed most commonly during saphenous vein graft intervention, rotational atherectomy and primary PCI for acute ST-elevation myocardial infarction. The contributions of distal embolization and ischemia/reperfusion injury to the pathogenesis of no-reflow vary in these settings, as does prevention and management. Prevention of no-reflow in these high-risk groups is the best treatment strategy, employing antiplatelet agents, vasodilators and/or mechanical devices to prevent distal embolization. Once mechanical factors are excluded as a cause for reduced epicardial flow, the treatment of established no-reflow is mainly pharmacologic, since the obstruction occurs at the level of the microvasculature. Compared with patients in whom no-reflow is transient, refractory no-reflow is associated with a markedly increased risk of 30-day mortality.

IKKbeta inhibition attenuates myocardial injury and dysfunction following acute ischemia-reperfusion injury

Despite years of experimental and clinical research, myocardial ischemia-reperfusion (IR) remains an important cause of cardiac morbidity and mortality. The transcription factor nuclear factor-kappaB (NF-kappaB) has been implicated as a key mediator of reperfusion injury. Activation of NF-kappaB is dependent upon the phosphorylation of its inhibitor, IkappaBalpha, by the specific inhibitory kappaB kinase (IKK) subunit, IKKbeta. We hypothesized that specific antagonism of the NF-kappaB inflammatory pathway through IKKbeta inhibition reduces acute myocardial damage following IR injury. C57BL/6 mice underwent left anterior descending (LAD) artery ligation and release in an experimental model of acute IR. Bay 65-1942, an ATP-competitive inhibitor that selectively targets IKKbeta kinase activity, was administered intraperitoneally either prior to ischemia, at reperfusion, or 2 h after reperfusion. Compared with untreated animals, mice treated with IKKbeta inhibition had significant reduction in left ventricular infarct size. Cardiac function was also preserved following pretreatment with IKKbeta inhibition. These findings were further associated with decreased expression of phosphorylated IkappaBalpha and phosphorylated p65 in myocardial tissue. In addition, IKKbeta inhibition decreased serum levels of TNF-alpha and IL-6, two prototypical downstream effectors of NF-kappaB activity. These results demonstrate that specific IKKbeta inhibition can provide both acute and delayed cardioprotection and offers a clinically accessible target for preventing cardiac injury following IR.

Nitric Oxide Inhalation Improves Microvascular Flow and Decreases Infarction Size After Myocardial Ischemia and Reperfusion

OBJECTIVES

The purpose of this study was to test if nitric oxide (NO) could improve microvascular perfusion and decrease tissue injury in a porcine model of myocardial ischemia and reperfusion (I/R).

BACKGROUND

Inhaled NO is a selective pulmonary vasodilator with biologic effects in remote vascular beds.

METHODS

In 37 pigs, the midportion of the left anterior descending coronary artery was occluded for 50 min followed by 4 h of reperfusion. Pigs were treated with a saline infusion (control; n = 14), intravenous nitroglycerin (IV-NTG) at 2 microg/kg/min (n = 11), or inhaled nitric oxide (iNO) at 80 parts per million (n = 12) beginning 10 min before balloon deflation and continuing throughout reperfusion.

RESULTS

Total myocardial oxidized NO species in the infarct core was greater in the iNO pigs than in the control or IV-NTG pigs (0.60 +/- 0.05 nmol/mg tissue vs. 0.40 +/- 0.03 nmol/mg tissue and 0.40 +/- 0.02 nmol/mg tissue, respectively; p < 0.01 for both). Infarct size, expressed as percentage of left ventricle area at risk (AAR), was smaller in the iNO pigs than in the control or IV-NTG pigs (31 +/- 6% AAR vs. 58 +/- 7% AAR and 46 +/- 7% AAR, respectively; p < 0.05 for both) and was associated with less creatine phosphokinase-MB release. Inhaled NO improved endocardial and epicardial blood flow in the infarct zone, as measured using colored microspheres (p < 0.001 vs. control and IV-NTG). Moreover, NO inhalation reduced leukocyte infiltration, as reflected by decreased cardiac myeloperoxidase activity (0.8 +/- 0.2 U/mg tissue vs. 2.3 +/- 0.8 U/mg tissue in control and 1.4 +/- 0.4 U/mg tissue in IV-NTG; p < 0.05 for both) and decreased cardiomyocyte apoptosis in the infarct border zone.

CONCLUSIONS

Inhalation of NO just before and during coronary reperfusion significantly improves microvascular perfusion, reduces infarct size, and may offer an attractive and novel treatment of myocardial infarction.

Adenosine as a Non-Opioid Analgesic in the Perioperative Setting

Adenosine, a ubiquitous metabolic intermediate in the body, is involved in nearly every aspect of cell function, including neuromodulation and neurotransmission. Adenosine A(1) and A(2) receptors are widely distributed in the brain and spinal cord, and are a novel, non-opiate target for pain management. The potential of adenosine as a non-narcotic analgesic in anesthetized patients has been explored in clinical trials, including double-blind studies versus placebo and remifentanil infusion. These studies suggest that, compared to placebo or remifentanil, an intraoperative adenosine infusion stabilizes core hemodynamics and reduces the requirement for anesthesia during surgery. Further, adenosine improves postoperative recovery, as indicated by lower pain scores and less opioid consumption. The safety profile of adenosine has been well characterized based on use of currently approved adenosine products. The most common adverse events associated with its use include flushing, chest discomfort, dyspnea, headache, gastrointestinal discomfort, and lightheadedness. These effects are generally well tolerated and transient. Further studies are warranted to investigate the full potential of adenosine as a non-opioid analgesic in the perioperative setting.

Postconditioning the Human Heart with Adenosine in Heart Valve Replacement Surgery

BACKGROUND

The effect of adenosine postconditioning on myocardial protection in cardiac surgery remains uncertain. The present study evaluated the safety, feasibility, and beneficial effect of adenosine postconditioning as an adjunct to predominantly used cold-blood cardioplegic myocardial protection method in the setting of heart valve replacement operations.

METHODS

Sixty patients with rheumatic heart valve disease undergoing heart valve replacement operations were randomized to an adenosine (1.5 mg/kg) or saline (as control) bolus injection through an arterial catheter immediately after the aorta cross-clamp was removed. The surgical indications were similar in both groups, and heart valve replacement was successful in all patients.

RESULTS

The extubation time and postoperative hospital time were similar in both groups. Compared with the control group, however, the inotrope scores in the intensive care unit (ICU) were much lower (p < 0.01), and the ICU time was significantly shorter (p < 0.05) in adenosine group. More important, cardiac troponin I release was less in the adenosine group, especially at 12 and 24 hours after reperfusion (p < 0.01), and total cardiac troponin I release estimated with the area under curve was also significantly reduced during the first 24 hours after reperfusion (p < 0.01).

CONCLUSIONS

A 1.5-mg/kg bolus administration of adenosine through an arterial catheter immediately after the aorta cross-clamp is removed is feasible and well tolerated in patients undergoing heart valve replacement. An adenosine postconditioning adjunct to high potassium cold blood myocardial protection is related to less troponin I release, less inotropic drug use, and shorter ICU stay.

Reperfusion injury salvage kinase signalling: taking a RISK for cardioprotection

Following an acute myocardial infarction (AMI), early coronary artery reperfusion remains the most effective means of limiting the eventual infarct size. The resultant left ventricular systolic function is a critical determinant of the patient's clinical outcome. Despite current myocardial reperfusion strategies and ancillary antithrombotic and antiplatelet therapies, the morbidity and mortality of an AMI remain significant, with the number of patients developing cardiac failure increasing, necessitating the development of novel strategies for cardioprotection which can be applied at the time of myocardial reperfusion to reduce myocardial infarct size. In this regard, the Reperfusion Injury Salvage Kinase (RISK) Pathway, the term given to a group of pro-survival protein kinases (including Akt and Erk1/2), which confer powerful cardioprotection, when activated specifically at the time of myocardial reperfusion, provides an amenable pharmacological target for cardioprotection. Preclinical studies have demonstrated that an increasing number of agents including insulin, erythropoietin, adipocytokines, adenosine, volatile anesthetics natriuretic peptides and 'statins', when administered specifically at the time of myocardial reperfusion, reduce myocardial infarct size through the activation of the RISK pathway. This recruits various survival pathways that include the inhibition of mitochondrial permeability transition pore opening. Interestingly, the RISK pathway is also recruited by the cardioprotective phenomena of ischemic preconditioning (IPC) and postconditioning (IPost), enabling the use of pharmacological agents which target the RISK pathway, to be used at the time of myocardial reperfusion, as pharmacological mimetics of IPC and IPost. This article reviews the origins and evolution of the RISK pathway, as part of a potential common cardioprotective pathway, which can be activated by an ever-expanding list of agents administered at the time of myocardial reperfusion, as well as by IPC and IPost. Preliminary clinical studies have demonstrated myocardial protection with several of these pharmacological activators of the RISK pathway in AMI patients undergoing PCI. Through the use of appropriately designed clinical trials, guided by the wealth of existing preclinical data, the administration of pharmacological agents which are known to activate the RISK pathway, when applied as adjuvant therapy to current myocardial reperfusion strategies for patients presenting with an AMI, should lead to improved clinical outcomes in this patient group.

Reperfusion injury as a therapeutic challenge in patients with acute myocardial infarction

Cardiomyocyte death secondary to transient ischemia occurs mainly during the first minutes of reperfusion, in the form of contraction band necrosis involving sarcolemmal rupture. Cardiomyocyte hypercontracture caused by re-energisation and pH recovery in the presence of impaired cytosolic Ca(2+) control as well as calpain-mediated cytoskeletal fragility play prominent roles in this type of cell death. Hypercontracture can propagate to adjacent cells through gap junctions. More recently, opening of the mitochondrial permeability transition pore has been shown to participate in reperfusion-induced necrosis, although its precise relation with hypercontracture has not been established. Experimental studies have convincingly demonstrated that infarct size can be markedly reduced by therapeutic interventions applied at the time of reperfusion, including contractile blockers, inhibitors of Na(+)/Ca(2+) exchange, gap junction blockers, or particulate guanylyl cyclase agonists. However, in most cases drugs for use in humans have not been developed and tested for these targets, while the effect of existing drugs with potential cardioprotective effect is not well established or understood. Research effort should be addressed to elucidate the unsolved issues of the molecular mechanisms of reperfusion-induced cell death, to identify and validate new targets and to develop appropriate drugs. The potential benefits of limiting infarct size in patients with acute myocardial infarction receiving reperfusion therapy are enormous.

Frequency of slow coronary flow following successful stent implantation and effect of Nitroprusside

Nitroprusside (NTP) is used for the treatment of slow coronary flow (SCF) after coronary interventions. The wide variation in dosage, route, and timing of its administration in the reported studies prevents an objective assessment of its efficacy. We report the incidence and response to a standardized NTP protocol of SCF after successful stent implantation. Selective intracoronary administration of incremental doses (initial bolus of 80 microg incremented by 40 microg) of NPT was assessed in 21 patients who developed SCF in a series of 2,212 consecutive patients who underwent successful stent placement from January to October 2005. SCF was observed only in patients treated for acute myocardial infarction (AMI; 11.5%, 12 of 105) or saphenous vein graft (SVG) stenosis (8.2%, 9 of 109). An intracoronary bolus of nitroglycerin did not restore normal Thrombolysis In Myocardial Infarction (TIMI) flow in any patient. The first 80-microg dose of NTP restored normal TIMI flow in 58% of patients (7 of 12) with AMI and in 44% of patients (4 of 9)with SVG stenosis. The maximal dose (120/160 microg) restored normal TIMI flow in all remaining patients with AMI but in only 1 additional patient with SVG stenosis. At the end of the procedure, the percent decrease in corrected TIMI frame count was significantly larger in patients with AMI (-44+/-10%) than in those with SVG stenosis (-24+/-16%, p=0.02). In a large consecutive series of successful stent procedures, SCF was found only in patients with ST-elevation AMI (11.5%) or with a stenosed SVG (8.2%). In conclusion, the standardized protocol of intracoronary NTP administration succeeded in normalizing SCF in all patients with AMI but in only 5 of 9 patients with SVG stenosis. This latter subgroup requires other therapeutic strategies.

Adjunctive mechanical devices to prevent distal embolization in patients undergoing mechanical revascularization for acute myocardial infarction: a meta-analysis of randomized trials

BACKGROUND

The benefits of adjunctive mechanical devices to prevent distal embolization in patients with acute myocardial infarction (AMI) are still a matter of debate. The aim of this meta-analysis was to combine data from all randomized trials conducted with adjunctive mechanical devices to prevent distal embolization in AMI.

METHODS

The literature was scanned by formal searches of electronic databases (MEDLINE and Central) from January 1990 to October 2006, scientific session abstracts (from January 1990 to October 2006), and oral presentation and/or expert slide presentations (from January 2002 to October 2006) (on the Transcatheter Cardiovascular Therapeutics, American Heart Association, European Society of Cardiology, American College of Cardiology, and European Percutaneous Revascularization Web sites). We examined all randomized trials on adjunctive mechanical devices to prevent distal embolization in AMI. The following key words were used: randomized trial, myocardial infarction, reperfusion, primary angioplasty, rescue angioplasty, thrombectomy, thrombus aspiration, proximal or distal protection device, X-sizer, Diver, Export Catheter, Angiojet, Rescue catheter, Pronto catheter, PercuSurge, GuardWire, FilterWire, and SpideRX. Disagreements were resolved by consensus.

RESULTS

A total of 21 trials with 3721 patients were included (1877 patients [50.4%] in the adjunctive mechanical device group and 1844 [49.6%] in the control group); 1502 patients (40.3%) were randomized in trials with distal protection devices, and 2219 patients (59.7%) were randomized in trials with thrombectomy devices. Adjunctive mechanical devices were associated with a higher rate of postprocedural TIMI 3 flow (89.4% vs 87.1%, P = .03), a significantly higher rate of postprocedural myocardial blush grade 3 (48.8% vs 36.5%, P < .0001), and less distal embolization (6.0% vs 9.3%, P = .008), without any benefit in terms of 30-day mortality (2.5% vs 2.6%, P = .88). No difference was observed in terms of coronary perforations (0.27% vs 0.07%, P = .24).

CONCLUSIONS

This meta-analysis demonstrates that, among patients with AMI treated with percutaneous coronary intervention, the use of adjunctive mechanical devices to prevent distal embolization is associated with better myocardial perfusion and less distal embolization, but without an apparent improvement in survival.

The no-reflow phenomenon: A basic mechanism of myocardial ischemia and reperfusion

Both animal models of experimental myocardial infarction and clinical studies on reperfusion therapy for acute myocardial infarction have provided evidence of impaired tissue perfusion at the microvascular level after initiation of reperfusion despite adequate restoration of epicardial vessel patency. Characteristics of this "no-reflow" phenomenon found in basic science investigations, such as distinct perfusion defects, progressive decrease of resting myocardial flow with ongoing reperfusion and functional vascular alterations are paralleled by clinical observations demonstrating similar features during the course of reperfusion. In experimental animal investigations of coronary occlusion and reperfusion, this no-reflow phenomenon could be characterized as a fundamental mechanism of myocardial ischemia and reperfusion. Major determinants of the amount of no-reflow are the duration of occlusion, infarct size, but also the length of reperfusion, as rapid expansion of perfusion defects occurs during reperfusion. Moreover, no-reflow appears to persist over a period of at least four weeks, a period when major steps of infarct healing take place. The significant association of the degree of compromised tissue perfusion at four weeks and indices of infarct expansion, found in chronic animal models of reperfused myocardial infarction, might be the pathoanatomic correlate for the prognostic significance observed in the clinical setting.

Coronary microembolization

Atherosclerotic plaque rupture is the key event in the pathogenesis of acute coronary syndromes and it also occurs during coronary interventions. Atherosclerotic plaque rupture does not always result in complete thrombotic occlusion of the epicardial coronary artery with subsequent impending myocardial infarction, but may in milder forms result in the embolization of atherosclerotic and thrombotic debris into the coronary microcirculation. This review summarizes the present experimental pathophysiology of coronary microembolization in animal models of acute coronary syndromes and highlights the main consequences of coronary microembolization--reduced coronary reserve, microinfarction, inflammation and oxidative modification of contractile proteins, contractile dysfunction and perfusion-contraction mismatch.Furthermore, the review presents the available clinical evidence for coronary microembolization in patients and compares the clinical observations with observations in the experimental model.

Early management of ST elevation myocardial infarction: a review of practice

The last two decades of the 20th century witnessed continuous evolution in the understanding of the pathophysiology of ST elevation myocardial infarction. In parallel, the management of these patients developed steadily throughout this time and into the early years of the 21st century. From humble beginnings involving oxygen therapy, bed rest and analgesia, the relative merits of different strategies to open 'infarct-related arteries' (IRAs) are now being debated: pharmacological reperfusion, mechanical reperfusion or a combination of both these modalities. The current understanding of the process of thrombotic occlusion of the coronary artery has led to the appreciation of the importance of not simply opening the IRA, but also maintaining its patency once opened. Considerable attention is now being afforded to the significant minority of patients who do not achieve early, complete myocardial reperfusion, despite restoration of adequate flow down the epicardial IRA. Those patients who fail to achieve myocardial reperfusion, either due to late presentation or failure of reperfusion therapy, and are left with permanent myocardial scarring can now be considered. This article critically appraises the recent and emerging evidence and clinical implications of the contemporary management of ST elevation myocardial infarction.

Successful thrombus extraction with the Rescue thrombus management system during acute percutaneous coronary intervention improves flow but does not necessarily restore optimal myocardial tissue perfusion

We determined the effectiveness of the Rescue device in restoring flow and achieving optimal tissue perfusion during percutaneous coronary intervention (PCI) in thrombus-laden coronary arteries.

METHODS

A total of 30 patients with an acute coronary syndrome underwent PCI using the Rescue device.

RESULTS

The mean age was 65.5 +/- 9.8 years. Although the Rescue device could not be passed across the lesion in 6 (20%) cases, debris was aspirated in 26 (87%). The uncorrected TIMI frame count improved following the use of the Rescue device and improved further at the completion of PCI (92.2 +/- 23.9 pre-PCI vs. 38.7 +/- 31.3 post-Rescue vs. 21.96 +/- 24 post-PCI, P < 0.0001). The thrombus score improved from 4 +/- 0 to 2.2 +/- 1.29 to 0.86 +/- 1.4 (P < 0.0001). TIMI flow grade (TFG) 3 was restored in 60% of cases following the Rescue device and in 87% after PCI. Myocardial blush grade 3 occurred in only 13% of patients following the Rescue device and 37% of patients after PCI.

CONCLUSION

These data suggest that the Rescue device can aspirate considerable amounts of debris in the majority of patients and significantly improves the angiographic epicardial coronary blood flow. How effective such a device is in improving tissue perfusion and, thereby, clinical outcomes for patients remains to be seen.

Different effects of adenosine and calcium channel blockade on myocardial no-reflow after acute myocardial infarction and reperfusion

BACKGROUND

Adenosine and calcium channel blockers have been used in the treatment of angiographic no-reflow directly after angioplasty for acute myocardial infarction (AMI). However, their effects on tissue perfusion after AMI and reperfusion are undefined. The present study was designed to compare the effect of adenosine with that of the calcium channel blockers diltiazem and verapamil on myocardial no-reflow.

MATERIALS AND METHODS

Coronary ligation area and area of no-reflow were determined with both myocardial contrast echocardiography in vivo and histopathological evaluation in 44 Yorkshire mini-swines randomized into five study groups: ten in control, eight in adenosine-treated, nine in diltiazem-treated, nine in verapamil-treated and eight in sham-operated. An acute myocardial infarction and reperfusion model was created with 3-h occlusion of the left anterior descending coronary artery followed by 1-h reperfusion.

RESULTS

Compared with the control group, adenosine significantly decreased the area of no-reflow measured with both methods from 78.5 and 82.3% to 20.7 and 21.5% of ligation area, respectively (both P < 0.01), reduced necrosis area, maintained VE-cadherin, beta-catenin and gamma-catenin levels in reflow myocardium (P < 0.05-0.01). Although diltiazem and verapamil also significantly decreased the area of no-reflow, they failed to significantly modify necrosis area, VE-cadherin, beta-catenin and gamma-catenin levels.

CONCLUSIONS

These findings support the concept that adenosine can reduce both structural and functional no-reflow, while calcium channel blockade can only reduce functional no-reflow.

No-reflow phenomenon and prognosis in patients with acute myocardial infarction

The rapid restoration of coronary flow to the jeopardized myocardium has become an essential part of therapy after acute myocardial infarction. Despite an open infarct-related artery, breakdown of or obstruction to coronary microvasculature can markedly reduce blood flow to the infarct zone. This effect is known as the no-reflow phenomenon. Advances in imaging modalities have improved visualization of no reflow, showing its frequency to be higher than was estimated by clinical judgment alone. This phenomenon is important because it correlates with infarct size and provides useful prognostic information. No reflow is associated with reduced left ventricular ejection fraction, left ventricular remodeling, and poor clinical outcomes, placing patients with this effect in a high-risk group among reperfused patients. The focus of reperfusion therapy is shifting towards improved myocardial perfusion, which could promote functional recovery of viable muscle, reduce infarct expansion, and increase the delivery of blood-borne components, thereby accelerating the healing process. Various pharmacologic interventions and catheter-based devices to retrieve embolic materials have been proposed. Further studies to improve understanding of the pathophysiology of microvascular dysfunction will, however, help in the further development of preventive and therapeutic strategies. In this article, I discuss in depth the data available on the no-reflow phenomenon.

Intracoronary nitroprusside for the prevention of the no-reflow phenomenon after primary percutaneous coronary intervention in acute myocardial infarction. A randomized, double-blind, placebo-controlled clinical trial

BACKGROUND

The aim of this study was to test whether nitroprusside (NTP) injected intracoronary immediately before primary angioplasty for acute ST-elevation acute myocardial infarction (STEMI) prevents no-reflow and improves vessel flow and myocardial perfusion.

METHODS

Ninety-eight patients presenting with STEMI were evenly randomized to receive either NTP (60 microg) or placebo. The drug was selectively injected into the infarct-related artery, distal to the occlusion, in a double-blind manner. The primary end points were postintervention angiographic corrected thrombolysis in myocardial infarction frame count and the proportion of patients with complete (>70%) ST-segment elevation resolution. Secondary end points included myocardial blush score and clinical outcome at 6 months follow-up.

RESULTS

Mean (+/-SD) age was 62 (+/-12) years, and 87% were men. Baseline characteristics (excluding sex) did not differ between groups. The corrected thrombolysis in myocardial infarction frame count after angioplasty was 20.8 (+/-18.6) and 20.3 (+/-21.3) in patients given NTP and placebo, respectively (P = .78). Complete ST-segment resolution was achieved in 61.7% and 61.2% of NTP and placebo subjects, respectively (P = .96). The distribution of myocardial blush score did not differ between groups. At 6 months, the rate of target lesion revascularization, myocardial infarction, or death occurred in 6.3% of the NTP group and 20.0% of the placebo group (P = .05).

CONCLUSIONS

In patients with STEMI, selective intracoronary administration of a fixed dose of NTP failed to improve coronary flow and myocardial tissue reperfusion but improved clinical outcomes at 6 months.

Does Proximal Location of Culprit Lesion Confer Worse Prognosis in Patients Undergoing Primary Percutaneous Coronary Intervention for ST Elevation Myocardial Infarction?

ST segment elevation myocardial infarction (STEMI) from proximally located culprit lesion is associated with greater myocardium at jeopardy. In STEMI patients treated with thrombolytics, proximal culprit lesions are known to have worse prognosis. This relation has not been studied in patients undergoing primary percutaneous coronary intervention (PCI). In 3,535 STEMI patients with native coronary artery occlusion pooled from the primary angioplasty in myocardial infarction database, we compared in-hospital and 1-year outcomes between those with proximal (n = 1,606) versus non-proximal (n = 1,929) culprit lesions. Patients with proximal culprits were more likely to die and suffer major adverse cardiovascular events (MACE) during the index hospital stay (3.8% vs 2.2%, P = 0.006; 8.2% vs 5.8%, P = 0.0066, respectively) as well as during 1-year follow-up (6.9% vs 4.5%, P = 0.0013; 22% vs 17%, P = 0.003, respectively) compared to those with non-proximal culprits. After adjustment for baseline differences, proximal culprit was independently predictive of in-hospital death (adjusted odds ratio% 1.58, 95% confidence intervals, CI 1.05-2.40) and MACE (OR 1.41, CI 1.06-1.86), but not 1-year death or MACE. In addition, proximal culprit was independently associated with higher incidence of ventricular arrhythmias and sustained hypotension during the index hospitalization. The univariate impact of proximal culprit lesion on in-hospital death and MACE was comparable to other adverse angiographic characteristics, such as multivessel disease and poor initial thrombolysis in myocardial infarction flow, and greater than that of anterior wall STEMI. In conclusion, proximal location of the culprit lesion is a strong independent predictor of worse in-hospital outcomes in patients with STEMI undergoing primary PCI.

Post-Reperfusion Myocardial Infarction

OBJECTIVES

The purpose of this study was to assess the safety and efficacy of the adenosine regulating agent (ARA) acadesine for reducing long-term mortality among patients with post-reperfusion myocardial infarction (MI).

BACKGROUND

No prospectively applied therapy exists that improves long-term survival after MI associated with coronary artery bypass graft (CABG) surgery-a robust model of ischemia/reperfusion injury. Pretreatment with the purine nucleoside autocoid adenosine mitigates the extent of post-ischemic reperfusion injury in animal models. Therefore, we questioned whether use of the ARA acadesine-by increasing interstitial adenosine concentrations in ischemic tissue-would improve long-term survival after post-reperfusion MI.

METHODS

At 54 institutions, 2,698 patients undergoing CABG surgery were randomized to receive placebo (n = 1,346) or acadesine (n = 1,352) by intravenous infusion (0.1 mg/kg/min; 7 h) and in cardioplegia solution (placebo or acadesine; 5 microg/ml). Myocardial infarction was prospectively defined as: 1) new Q-wave and MB isoform of creatine kinase (CK-MB) elevation (daily electrocardiography; 16 serial CK-MB measurements); or 2) autopsy evidence. Vital status was assessed over 2 years, and outcomes were adjudicated centrally.

RESULTS

Perioperative MI occurred in 100 patients (3.7%), conferring a 4.2-fold increase in 2-year mortality (p < 0.001) compared with those not suffering MI. Acadesine treatment, however, reduced that mortality by 4.3-fold, from 27.8% (15 of 54; placebo) to 6.5% (3 of 46; acadesine) (p = 0.006), with the principal benefit occurring over the first 30 days after MI. The acadesine benefit was similar among diverse subsets, and multivariable analysis confirmed these findings.

CONCLUSIONS

Acadesine is the first therapy proven to be effective for reducing the severity of acute post-reperfusion MI, substantially reducing the risk of dying over the 2 years after infarction.

Role of Adenosine as Adjunctive Therapy in Acute Myocardial Infarction

Although early reperfusion and maintained patency is the mainstay therapy for ST elevation myocardial infarction, experimental studies demonstrate that reperfusion per se induces deleterious effects on viable ischemic cells. Thus "myocardial reperfusion injury" may compromise the full potential of reperfusion therapy and may account for unfavorable outcomes in high-risk patients. Although the mechanisms of reperfusion injury are complex and multifactorial, neutrophil-mediated microvascular injury resulting in a progressive decrease in blood flow ("no-reflow" phenomenon) likely plays an important role. Adenosine is an endogenous nucleoside found in large quantities in myocardial and endothelial cells. It activates four well-characterized receptors producing various physiological effects that attenuate many of the proposed mechanisms of reperfusion injury. The cardio-protective effects of adenosine are supported by its role as a mediator of pre- and post-conditioning. In experimental models, administration of adenosine in the peri-reperfusion period results in a marked reduction in infarct size and improvement in ventricular function. The cardioprotective effects in the canine model have a narrow time window with the drug losing its effect following three hours of ischemia. Several small clinical studies have demonstrated that administration of adenosine with reperfusion therapy reduces infarct size and improves ventricular function. In the larger AMISTAD and AMISTAD II trials a 3-h infusion of adenosine as an adjunct to reperfusion resulted in a striking reduction in infarct size (55-65%). Post hoc analysis of AMISTAD II showed that this was associated with significantly improved early and late mortality in patients treated within 3.17 h of symptoms. An intravenous infusion of adenosine for 3 h should be considered as adjunctive therapy in high risk-patients undergoing reperfusion therapy.

The role of vasodilators in the prevention and treatment of no-reflow following percutaneous coronary intervention

The routine use of vasodilators in patients with acute coronary syndromes or other groups undergoing percutaneous coronary intervention (PCI) cannot be recommended at present. However, in the event of no-reflow occurring following PCI, intracoronary adenosine or verapamil should be administered.

Amelioration of Ischemia/Reperfusion-Induced Myocardial Infarction by the 2-Alkynyladenosine Derivative 2-Octynyladenosine (YT-146)

The present study was aimed at determining whether the novel adenosine A2-agonist YT-146 may have cardioprotective effects against ischemia-reperfusion injury. Anesthetized open-chest dogs underwent 90-min occlusion of the left anterior descending artery and subsequent 300-min reperfusion. The animals were randomly assigned to receive vehicle, 3, or 10 microg/kg YT-146 or ischemic preconditioning (4 episodes of 5 min occlusion followed by 5 min of reperfusion). Blood pressure, heart rate, and regional myocardial blood flow throughout the experiment were measured, as was the myocardial infarct size after reperfusion. The infarct size of the vehicle-treated dog was 56.2% +/- 2.7% (n = 5), whereas that of 3 or 10 microg/kg YT-146-treated dog was smaller (ie, 29.5% +/- 8.7% or 20.2% +/- 7.0%, respectively; n = 5). The infarct size of the dog treated with 10 microg/kg YT-146 was reduced to a degree similar to that of the ischemic preconditioning (19.2% +/- 6.3%, n = 5). YT-146 at both doses elicited a dose-dependent increase in acute hyperemic coronary flow immediately after reperfusion. The cardioprotective effect may be attributed to the limitation of the infarct size, probably via A2-receptor-mediated coronary artery dilatation during the early period of reperfusion.

Prospective, randomised, controlled trial to study the effect of intracoronary injection of verapamil and adenosine on coronary blood flow during percutaneous coronary intervention in patients with acute coronary syndromes

OBJECTIVES

To study the impact of injection of verapamil and adenosine in the coronary arteries on TIMI (Thrombolysis in Myocardial Infarction) frame count (TFC) after percutaneous coronary intervention (PCI) in patients with an acute coronary syndrome (ACS).

METHODS

Prospective, randomised, controlled study of the intracoronary administration of normal saline versus verapamil versus adenosine in patients undergoing PCI in the setting of an ACS, even when flow is visually established to be normal or near normal. Patients were randomised to receive verapamil (n = 49), adenosine (n = 51) or normal saline (n = 50) after PCI. Quantitative angiography, TIMI flow grade (TFG), TFC and myocardial blush grade were assessed before PCI, after PCI and after drugs were given. Wall motion index (WMI) was measured at days 1 and 30.

RESULTS

9 patients in the verapamil group developed transient heart block, not seen with adenosine (p <or= 0.001). Compared with saline, coronary flow measured by TFC improved significantly and WMI improved slightly but insignificantly in both the verapamil (TFC: p = 0.02; mean difference in improvement in WMI: 0.09, 95% confidence interval (CI) 0.015 to 0.17, p = 0.02) and the adenosine groups (TFC: p = 0.002; mean difference in improvement in WMI: 0.08, 95% CI 0.004 to 0.16, p = 0.04). The improvements in TFC and WMI did not differ significantly between the verapamil and the adenosine groups (TFC: p = 0.2; mean difference in improvement in WMI: 0.01, 95% CI -0.055 to 0.08, p = 0.7, respectively).

CONCLUSION

Administration of verapamil or adenosine significantly improves coronary flow and WMI after PCI in the setting of an ACS. Flow and WMI did not differ significantly between verapamil and adenosine but verapamil was associated with the development of transient heart block.

Comparison of carvedilol and metoprolol in patients with acute myocardial infarction undergoing primary coronary intervention

BACKGROUND

The value of early therapy with beta-blocking agents in acute myocardial infarction (AMI) undergoing reperfusion is not yet well established. Newer beta-blocking agents such as carvedilol offer potential advantages in the setting of ischemia and reperfusion injury.

METHODS

We randomized 100 patients with acute ST-elevation myocardial infarction (STEMI) to receive either 12.5 mg carvedilol or 50 mg metoprolol tartrate orally already before percutaneous coronary intervention (PCI) of the infarct-related artery, uptitrating to a daily target dose of 50 mg carvedilol or 150 mg metoprolol during the first week. Pts. were subjected to left ventricular (LV) angiography just before reperfusion and after 14 days to compare ejection fraction (EF) and regional wall motion abnormalities by quantitative LV analysis. Furthermore, kinetics of cardiac troponin T (cTnT), NT-proANP, NT-proBNP, endothelin, argenine vasopressin, epinephrine and norepinephrine were assessed during the first 12 hours and again at 2 weeks. In addition, reperfusion-induced rhythm abnormalities like VT, triplets, couplets, and bradycardic events were assessed continuously during the first 12 hours starting at reperfusion by Holter analysis.

RESULTS

Both groups did not differ with respect to onset of pain, target vessel, extent of coronary heart disease, age, gender, rate of stenting or use of a GP IIb/IIIa inhibitor, pre- and postinterventional TIMI flow grade, time course of heart rate or blood pressure. There were neither significant differences in the cardiac and neurohumoral markers nor in the occurrence of arrhythmias between both treatment groups. Within 14 days, EF improved by 5.8+/-2.0% (mean+/-SEM) in the metoprolol group and by 5.2+/-2.1% in the carvedilol group (n.s.). Area of infarction was reduced by 6.1+/-2.9% in the metoprolol group and by 12.8+/-3.6% of total LV outline in the carvedilol group (n.s.). Maximum hypokinesia in the central infarcted region was diminished by 0.40+/-0.11 standard deviation (SD) in the metoprolol group and by 0.34+/-0.13 SD in the carvedilol group (n.s.).

CONCLUSION

In the setting of direct PCI in acute STEMI, administration of carvedilol before reperfusion appears not to be superior to metoprolol with respect to myocardial injury and improvement of global and regional LV function. The study documents equivalent improvement of LV function and similar kinetics of cardiac and neurohumoral markers in pts. with acute STEMI undergoing direct PCI if the pts. were immediately treated with either carvedilol or metoprolol. Thus, superiority of carvedilol in experimental studies did not translate into a clinical benefit.

Adenosine prevents neutrophil adhesion to human endothelial cells after hypoxia/reoxygenation

BACKGROUND

Neutrophil adhesion to vascular endothelium has been implicated in the pathogenesis of myocardial injury after ischaemia/reperfusion (IR) and the "no-reflow" phenomenon. Adenosine and sodium-nitroprusside (SNP) have been used clinically to ameliorate this injury. We set out to establish a human cellular model for the study of IR and to evaluate the effects of adenosine and SNP on neutrophil adhesion in vitro.

METHODS

Cultured human umbilical vein endothelial cells (HUVEC) were exposed to hypoxia (5% CO2, 95% N2) or normoxia (room air, 5% CO2) for 2 h, followed by reoxygenation for 30 min (IR condition). Human neutrophils were then added together with adenosine (50 microM), SNP (10 microM) or no additive (control). After incubation for 1 h, neutrophil adhesion to endothelial cells was quantified via automated cell counts. The experiment was repeated with the adenosine treatment alone, with and without the addition of the adenosine A2A receptor blocker ZM-241385.

RESULTS

Compared with baseline neutrophil adhesion after normoxia, hypoxia followed by reoxygenation increased adhesion to 189+/-43% (p=0.01), but this effect was prevented by the addition of adenosine (109+/-17%, p=NS compared to control conditions). SNP did not affect the increased adhesion caused by hypoxia (166+/-25%, p=NS). The addition of ZM-241385 did not inhibit the effect of adenosine on neutrophil adhesion after hypoxia/reoxygenation.

CONCLUSIONS

Exposure of human endothelial cells to hypoxia/reoxygenation causes increased neutrophil adhesion. This effect is prevented by adenosine, but not mediated by the A2A receptor. SNP does not prevent neutrophil adhesion after IR in vitro.

Improvement in microvascular reflow and reduction of infarct size with adenosine in patients undergoing primary coronary stenting

The aim of this study was to use myocardial contrast echocardiography to evaluate the effect of intravenous adenosine on microvascular reflow in patients with acute myocardial infarction who underwent primary coronary stenting (PCS). Thirty patients who underwent primary PCS for acute myocardial infarction were randomized to intravenous adenosine (50 to 70 mug/kg/min) or vehicle for 3 hours. Myocardial contrast echocardiography was performed before and sequentially after PCS to determine the risk area during coronary occlusion and infarct size. The risk area was similar in the adenosine- and placebo-treated patients. The infarct size as a ratio to the risk area was smaller in patients treated with adenosine when measured at 3 to 5 days (0.37 +/- 0.29 vs 0.68 +/- 0.25, p <0.01) and at 4 weeks (0.34 +/- 0.26 vs 0.60 +/- 0.21, p <0.01) after PCS. This effect was greatest when patency was achieved <4 hours after symptom onset (0.18 +/- 0.18 vs 0.74 +/- 0.31, p <0.05), with little effect after 4 hours. The relative microvascular blood volume in the risk area at 4 weeks was higher in patients receiving adenosine than in those receiving placebo (0.73 +/- 0.22 vs 0.57 +/- 0.20, p <0.01), and was highest when patency was achieved in <4 hours. In conclusion, the adjunctive use of intravenous adenosine after PCS reduces the infarct size relative to the risk area. This beneficial effect occurs primarily in those undergoing early intervention.

Left ventricular remodeling after primary coronary angioplasty in patients treated with abciximab or intracoronary adenosine

BACKGROUND

Primary angioplasty is the best treatment of acute myocardial infarction but fails to achieve adequate myocardial reperfusion in 25% to 30% of patients, despite TIMI grade 3 flow. Drug treatment aimed at reducing the no-reflow phenomenon may improve myocardial salvage, thus preventing left ventricular remodeling. Our aim was to evaluate the impact of abciximab and adenosine on immediate angiographic results and on 6-month left ventricular remodeling.

METHODS

Ninety consecutive patients undergoing primary angioplasty with coronary stenting were randomized in a sequential alternating fashion to standard abciximab treatment (ABCX) group, intracoronary adenosine distal to the occlusion (ADO) group, or neither (CTRL) group. All patients underwent a clinical and echocardiographic follow-up at 1 and 6 months. The primary end point was the prevalence of 6-month left ventricular remodeling.

RESULTS

Baseline clinical, echocardiographic, and angiographic characteristics were similar. Mean final corrected TIMI frame count was 17 +/- 9, 16 +/- 12, and 23 +/- 11 frames in ABCX, ADO, and CTRL patients, respectively (P = .002). Angiographic no-reflow was observed in 7%, 13%, and 17% of ABCX, ADO, and CTRL patients, respectively (P > .20). At 6 months, left ventricular remodeling occurred in 7%, 30%, and 30% of ABCX, ADO, and CTRL patients, respectively (P = .045), with a percent increase in end-diastolic volume of 5% +/- 13%, 15% +/- 15%, and 12% +/- 18% (P = .04).

CONCLUSIONS

During primary angioplasty, abciximab enhances myocardial reperfusion, translating into a reduced incidence of 6-month left ventricular remodeling. In contrast, adenosine administration improves angiographic results but does not prevent left ventricular remodeling.

Unsuccessful reperfusion in patients with ST-segment elevation myocardial infarction treated by primary angioplasty

BACKGROUND

Several studies have shown that patency of the epicardial vessel does not guarantee optimal myocardial perfusion in patients undergoing primary angioplasty for ST-segment elevation myocardial infarction (STEMI). The aim of the current study was to identify clinical and angiographic correlates of unsuccessful reperfusion by the use of myocardial blush grade in a large consecutive cohort of STEMI patients.

METHODS

Our population is represented by a total of 1,548 consecutive patients with STEMI treated by primary angioplasty at our institution. All clinical and angiographic data were prospectively collected. Successful reperfusion was defined as postprocedural thrombolysis in myocardial infarction (TIMI) 3 flow with myocardial blush grades 2 to 3.

RESULTS

Poor myocardial reperfusion was observed in 358 patients (23.1%) and was associated with a significantly larger infarct size (1838 [350-3387] vs 1187 [607-2257], P < .0001) and lower ejection fraction (41 [31-48.2] vs 65 [36.5-52.5] P < .0001). At multivariate analysis, preprocedural TIMI flow 0 to 1, anterior infarction, ischemic time, postprocedural residual stenosis, advanced Killip class at presentation, and age were identified as independent predictors of poor myocardial reperfusion. At 1-year follow-up, a total of 92 patients (5.9%) had died. At multivariate analysis, including clinical and angiographic variables, unsuccessful reperfusion was an independent predictor of 1-year mortality (relative risk 3.11, 95% CI 1.99-4.87, P < .0001).

CONCLUSIONS

The prevalence of poor myocardial reperfusion is relatively high in patients undergoing primary angioplasty for STEMI, with a significant impact on 1-year mortality. Preprocedural TIMI flow, anterior infarction, ischemic time, Killip class at presentation, and age were independently associated with unsuccessful reperfusion. Future research should be focused on these high-risk patients, and treatment strategies should be developed to improve myocardial perfusion and clinical outcome.

X-sizer for thrombectomy in acute myocardial infarction improves ST-segment resolution: results of the X-sizer in AMI for negligible embolization and optimal ST resolution (X AMINE ST) trial

OBJECTIVES

We sought to compare, in a prospective randomized multicenter study, the effect of adjunctive thrombectomy using X-Sizer (eV3, White Bear Lake, Minnesota) before percutaneous coronary intervention (PCI) versus conventional PCI in patients with acute myocardial infarction (AMI) for <12 h and Thrombolysis In Myocardial Infarction (TIMI) flow grade 0 to 1. The primary end point was the magnitude of ST-segment resolution after PCI.

BACKGROUND

Despite a high rate of TIMI flow grade 3 achieved by PCI in patients with AMI, myocardial reperfusion remains relatively low. Distal embolization of thrombotic materials may play a major role in this setting.

METHODS

We conducted a prospective, randomized, multicenter study in patients with AMI <12 h and initial TIMI flow grade 0 to 1 who were treated with primary PCI. The magnitude of ST-segment resolution 1 h after PCI was the primary end point.

RESULTS

A total of 201 patients were included. Treatment groups were comparable by age (61 +/- 13 years), diabetes (22%), previous MI (8%), anterior MI (52%), onset-to-angiogram (258 +/- 173 min), and glycoprotein IIb/IIIa inhibitor use (59%). The magnitude of ST-segment resolution was greater in the X-Sizer group compared with the conventional group (7.5 vs. 4.9 mm, respectively; p = 0.033) as ST-segment resolution >50% (68% vs. 53%; p = 0.037). The occurrence of distal embolization was reduced (2% vs. 10%; p = 0.033) and TIMI flow grade 3 was obtained in 96% vs. 89%, respectively (p = 0.105). Myocardial blush grade 3 was similar (30% vs. 31%; p = NS). Six-month clinical outcome was comparable (death, 6% vs. 4% and major adverse cardiac and cerebral events, 13% vs. 13%, respectively). By multivariate analysis, independent predictors of ST-segment resolution >50% were: younger age, non-anterior MI, use of the X-Sizer, and a short time interval from symptom onset.

CONCLUSIONS

Reducing thrombus burden with X-Sizer before stenting leads to better myocardial reperfusion, as illustrated by a reduced risk of distal embolization and better ST-segment resolution.