Incidence and importance of thrombolysis in myocardial infarction grade 3 flow after primary percutaneous transluminal coronary angioplasty for acute myocardial infarction

Plasminogen activator inhibitor-1 activity and long-term outcome in patients with ST-elevation myocardial infarction treated with primary percutaneous coronary intervention: a prospective cohort study

AIM

To determine the relationship between plasminogen activator inhibitor-1 (PAI-1) activity rise during the first 24 hours of ST-elevation myocardial infarction (STEMI) treatment and death after 5 years.

METHODS

From May 1, 2009 to March 23, 2010, 87 STEMI patients treated with primary percutaneous coronary intervention (PCI) at the Sestre Milosrdnice University Hospital Center were consecutively enrolled in prospective single-center cohort study. PAI-1 activity was determined on admission and 24 hours later. The primary end-point was death after 5 years. The predictive value of PAI-1 activity variables as biomarkers of death was assessed using receiver operating characteristic (ROC) curve, independent predictors of death were assessed using multivariate Cox regression, and covariates independently related to higher PAI-1 activity rise were assessed using linear regression.

RESULTS

Two patients died during the hospital treatment and 11 during the follow-up. PAI-1 activity rise had the largest area under curve (0.748) for predicting death rate (optimal cut-off point 3.7 U/mL, sensitivity 53.8%, specificity 90.5%). Patients with PAI-1 activity rise higher than 3.7 U/mL had significantly higher mortality (P<0.001). Kaplan-Meier survival curve diverged within the first year after STEMI. Independent predictors of death were PAI-1 rise and final Thrombolysis in Myocardial Infarction flow. PAI-1 activity rise was independently related to heart failure, thrombus aspiration, and body weight.

CONCLUSION

PAI-1 activity rise higher than 3.7 U/mL is associated with higher 5-year death rate in STEMI patients treated with primary PCI.

Impact of myocardial salvage assessed by (99m)Tc-sestamibi scintigraphy on cardiac autonomic function in patients undergoing mechanical reperfusion therapy for acute myocardial infarction

OBJECTIVES

The purpose of this study was to analyze the impact of myocardial salvage on cardiac autonomic function in patients undergoing mechanical reperfusion therapy for acute myocardial infarction (MI).

BACKGROUND

Heart rate deceleration capacity (DC) and heart rate turbulence slope (TS) are strong predictors of post-MI mortality. Salvage of jeopardized myocardium is the main mechanism by which patients benefit from reperfusion therapy. The impact of myocardial salvage on DC and TS is unknown.

METHODS

The study enrolled 854 consecutive patients undergoing mechanical reperfusion therapy for first MI. Paired (99m)Tc-sestamibi scintigraphy studies (acute and 7 to 14 days after reperfusion) were used to calculate myocardial salvage index. DC and TS were assessed from Holter recordings 7 to 14 days after reperfusion. Patients were categorized into 3 groups by salvage index: <30% (n = 244), 30% to 60% (n = 257), and > or =60% (n = 353).

RESULTS

In the 3 groups, DC was 5.2 (interquartile range 3.5 to 7.1) ms, 5.7 (4.1 to 7.3) ms, and 6.4 (5.0 to 8.0) ms, whereas TS was 5.3 (2.6 to 8.4) ms/R-R interval, 6.9 (3.2 to 11.7) ms/R-R interval, and 7.8 (4.1 to 13.2) ms/R-R interval, respectively (p < 0.0001 for both). After adjustment for left ventricular ejection fraction (LVEF), initial perfusion defect, creatine kinase, age, diabetes mellitus, sex, and medical therapy, patients with salvage index <30% had a 2.6-fold risk (95% confidence interval: 1.8 to 3.9, p < 0.001) of having abnormal DC (< or =4.5 ms) or TS (< or =2.5 ms/R-R interval) compared with patients with salvage index > or =60%. However, patients who had autonomic dysfunction defined by abnormal DC and TS had a poor prognosis independent of whether or not the salvage index was <30% (5-year mortality rates of 16.5% and 17.3%, respectively). In contrast, prognosis was excellent when both factors were normal (5-year mortality rates of 2.9% and 4.0%, respectively). Predictive value of impaired LVEF (< or =40%) was also independent of salvage index. Multivariably, both autonomic dysfunction and impaired LVEF were independent predictors of 5-year mortality.

CONCLUSIONS

In patients undergoing mechanical reperfusion therapy for acute MI, salvage index is an independent predictor of autonomic dysfunction but does not affect its prognostic value.

Abciximab in patients with acute ST-segment-elevation myocardial infarction undergoing primary percutaneous coronary intervention after clopidogrel loading: a randomized double-blind trial

BACKGROUND

The glycoprotein IIb/IIIa receptor inhibitor abciximab has improved the efficacy of primary percutaneous coronary interventions in patients with acute myocardial infarction. However, it is not known whether abciximab remains beneficial after adequate clopidogrel loading in patients with acute ST-segment-elevation myocardial infarction.

METHODS AND RESULTS

A total of 800 patients with acute ST-segment-elevation myocardial infarction within 24 hours from symptom onset, all treated with 600 mg clopidogrel, were randomly assigned in a double-blind fashion to receive either abciximab (n=401) or placebo (n=399) in the intensive care unit before being sent to the catheterization laboratory. The primary end point, infarct size measured by single-photon emission computed tomography with technetium-99m sestamibi before hospital discharge, was 15.7+/-17.2% (mean+/-SD) of the left ventricle in the abciximab group and 16.6+/-18.6% of the left ventricle in the placebo group (P=0.47). At 30 days, the composite of death, recurrent myocardial infarction, stroke, or urgent revascularization of the infarct-related artery was observed in 20 patients in the abciximab group (5.0%) and 15 patients in the placebo group (3.8%) (relative risk, 1.3; 95% CI, 0.7 to 2.6; P=0.40). Major bleeding complications were observed in 7 patients in each group (1.8%).

CONCLUSIONS

Upstream administration of abciximab is not associated with a reduction in infarct size in patients presenting with acute myocardial infarction within 24 hours of symptom onset and receiving 600 mg clopidogrel.

Predictors of infarct size after primary coronary angioplasty in acute myocardial infarction from pooled analysis from four contemporary trials

Determinates of infarct size in patients with acute myocardial infarction (AMI) undergoing percutaneous coronary intervention (PCI) have been incompletely characterized, in part because of the limited sample size of previous studies. Databases therefore were pooled from 4 contemporary trials of primary or rescue PCI (EMERALD, COOL-MI, AMIHOT, and ICE-IT), in which the primary end point was infarct size assessed using technetium-99m sestamibi single-photon emission computed tomographic imaging, measured at the same core laboratory. Of 1,355 patients, infarct size was determined using technetium-99m sestamibi imaging in 1,199 patients (88.5%), at a mean time of 23 +/- 15 days. Median infarct size of the study population was 10% (interquartile range 0% to 23%; mean 14.9 +/- 16.1%). Using multiple linear regression analysis of 18 variables, left anterior descending infarct artery, baseline Thrombolysis In Myocardial Infarction grade 0/1 flow, male gender, and prolonged door-to-balloon time were powerful independent predictors of infarct size (all p <0.0001). Other independent correlates of infarct size were final Thrombolysis In Myocardial Infarction grade <3 flow (p = 0.0001), previous AMI (p = 0.005), symptom-onset-to-door time (p = 0.021), and rescue angioplasty (p = 0.026). In conclusion, anterior infarction, time to reperfusion, epicardial infarct artery patency before and after reperfusion, male gender, previous AMI, and failed thrombolytic therapy were important predictors of infarct size after angioplasty in patients with AMI assessed using technetium-99m sestamibi imaging and should be considered when planning future trials of investigational drugs or devices designed to enhance myocardial recovery.

No-reflow phenomenon after acute myocardial infarction is associated with reduced clot permeability and susceptibility to lysis

OBJECTIVE

We assessed the relationship between fibrin clot properties and the no-reflow phenomenon after primary coronary intervention (PCI).

METHODS AND RESULTS

Epicardial blood flow was assessed by TIMI scale and corrected TIMI frame count (cTFC), and perfusion by TIMI Myocardial Perfusion Grade (TMPG) after PCI during ST-segment elevation myocardial infarction (STEMI). Fibrin clot permeability (K(s)) and susceptibility to lysis in assays using exogenous thrombin (t(50%)) and without thrombin (t(TF)) were determined in 30 no-reflow patients (TIMI < or = 2) and in 31 controls (TIMI-3) after uneventful 6 to 14 months from PCI. Patients with TIMI < or = 2 had lower K(s) by 18% (P<0.0001) and prolonged fibrinolysis by 33% for t(50%) (P<0.0001) and by 45% for t(TF) (P<0.0001). cTFC was correlated with K(s) (r=-0.56, P<0.0001), t(50%) (r=0.49, P<0.001), and t(TF) (r=0.54, P<0.001). K(s) increased in a stepwise fashion with TIMI flow (P<0.0001) and TMPG (P<0.0001), whereas both fibrinolysis times decreased with TIMI flow (P<0.0001 for both) and TMPG (P<0.01 for both). Multiple regression models showed that only K(s) and fibrinogen were independent predictors of cTFC (P<0.05 for both), TIMI < or = 2 flow (P<0.05 for both) and TMPG-0/1 (P<0.05 for both).

CONCLUSIONS

Survivors of myocardial infarction with a history of the no-reflow after PCI are characterized with more compact fibrin network and its resistance to lysis.

Effect of no-reflow during primary percutaneous coronary intervention for acute myocardial infarction on six-month mortality

No-reflow is a frequent event during percutaneous coronary intervention (PCI) for acute myocardial infarction (AMI), and it may affect cardiac prognosis. We evaluated the occurrence of no-reflow as a predictor of outcomes in patients who underwent PCI for AMI. We prospectively collected data from 599 consecutive patients who underwent stent-based PCI for ST-elevation AMI by identifying those with no-reflow (Thrombosis In Myocardial Infarction [TIMI] grade <3 flow at completion of the procedure) and analyzing their baseline characteristics and clinical outcomes. Patients with no-reflow (n = 40, 6.7%) were older (67 +/- 13 vs 60 +/- 13 years, p = 0.002) and had longer ischemic times (5.5 +/- 3.7 vs 4.4 +/- 3.0 hours, p = 0.04) with more TIMI grade 0/1 flow at presentation (90% vs 64%, p = 0.001). No-reflow occurred mostly (73%) after stenting and often required intra-aortic balloon pump counterpulsation (30% vs 4.3%, p <0.001). Peak creatine kinase level was higher in patients with no-reflow (2,700 +/- 1,900 vs 2,000 +/- 1,800, p = 0.03) and more often associated with moderate or severe left ventricular dysfunction (68% vs 45%, p = 0.006) and increased 6-month mortality (12.5% vs 4.3%, p = 0.04). By multivariate analysis, no-reflow was an independent predictor of long-term mortality (odds ratio 3.4, p = 0.02). In addition, renal failure (odds ratio 4.39, p = 0.0025) and preprocedure TIMI grade 0/1 flow (odds ratio 2.1, p = 0.003) were independent predictors of no-reflow. In conclusion, the association of no-reflow with longer ischemic time and worse initial TIMI flow may indicate the presence of highly organized thrombus burden with higher propensity for distal embolization. Regardless of its mechanism, no-reflow was an independent predictor of increased mortality.

The effect of verapamil on the restoration of myocardial perfusion and functional recovery in patients with angiographic no-reflow after primary percutaneous coronary intervention

OBJECTIVE

Angiographic thrombolysis in myocardial infarction (TIMI) flow grade < or = 2 after primary percutaneous coronary intervention (PCI), defined as angiographic no-reflow, predicts poor functional recovery in patients with acute myocardial infarction. We investigated the effect of verapamil on the restoration of myocardial perfusion and functional recovery in patients with angiographic no-reflow after PCI.

METHODS

99mTc tetrofosmin single photon emission computed tomographic (SPECT) imaging was performed (before, immediately after and 1 month after PCI) in 101 consecutive patients with acute myocardial infarction. The defect score was calculated as the sum of perfusion defect in a 13-segment model (scores of 3, complete defect to 0, normal perfusion). The asynergic score, defined as the number of asynergic segments, was assessed by echocardiography before and 1 month later. Multiple logistic regression analysis was performed to elucidate the effect of verapamil administration.

RESULTS

Of 101 patients, 32 (31%) had angiographic no-reflow and were divided into two groups: 18 patients with verapamil (group 1) and 14 patients without verapamil (group 2). Sixty-nine patients had TIMI grade 3 reflow after PCI (group 3). The change in the defect score 1 month after PCI in group 1 was significantly larger than that in group 2 (P = 0.003). The asynergic score improved more at 1 month in group 1 compared to that in group 2 (P = 0.007). Moreover, logistic regression analysis revealed that TIMI grade reflow < or = 2 after PCI (P = 0.04, OR = 5.51), the defect score before PCI (P = 0.03, OR = 1.15), the asynergic score before PCI (P = 0.01, OR = 0.64) and the administration of verapamil (P = 0.002, OR = 22.4) were independently associated with successful myocardial reperfusion immediately after PCI.

CONCLUSIONS

Intracoronary verapamil restored myocardial perfusion in patients with angiographic no-reflow after PCI and lead to better functional recovery after acute myocardial infarction.

Long-term prognostic implications of nonoptimal primary angioplasty for acute myocardial infarction

AIM

To evaluate the long-term outcome of a nonoptimal result of a primary percutaneous coronary intervention (PCI) for acute myocardial infarction (AMI).

METHODS AND RESULTS

An optimal PCI result was defined as TIMI flow grade 3 and residual stenosis < or = 20%. Long-term clinical follow-up (51 +/-+/- 21 months) data were collected from 1,009 consecutive patients with ST-elevation AMI who underwent primary PCI. Overall, an optimal primary PCI result was achieved in 958 patients (95%). At 5-year follow-up, patients with nonoptimal PCI had a higher rate of all-cause mortality (47% vs 19%; P < 0.00001 by log-rank test) than those with an optimal mechanical reperfusion. Fifty-two percent of the deaths in the nonoptimal PCI group occurred within the first month. Interestingly, after this period, estimated survival of 30-day alive patients was not significantly different to that of patients with an optimal PCI (P = 0.06 by log-rank test). Nonoptimal PCI result emerged as an independent predictor of 1-month mortality (OR = 3.030, 95% CI = 1.265-7.254; P = 0.013), but not of 5-year mortality. At long-term follow-up, cumulative rates of nonfatal reinfarction, hospitalization for heart failure, and additional revascularization procedures were similar between patients with nonoptimal and optimal primary PCI (4% vs 5%, P = 0.695; 4% vs 5%, P = 921; and 22% vs 20%, P = 0.816, respectively).

CONCLUSION

A nonoptimal primary PCI result represents a strong predictor of early mortality. However, in patients surviving the early phase, the incidence of clinical events at long-term follow-up seems to be similar to successfully reperfused AMI patients.

Myocardial salvage after reduced-dose thrombolysis combined with glycoprotein IIb/IIIa blockade versus thrombolysis alone in patients with acute myocardial infarction

BACKGROUND

The aim of study was to examine the efficacy of reduced-dose alteplase plus abciximab versus alteplase alone by quantifying the amount of myocardium salvaged using myocardial scintigraphy.

METHODS

This study analyzed 150 patients with acute myocardial infarction who received alteplase (69 patients) or reduced-dose alteplase plus abciximab (81 patients) in the setting of the Stent versus Thrombolysis for Occluded Coronary Arteries in Patients with Acute Myocardial Infarction (STOPAMI) 1 and 2 trials. Salvage index (proportion of initial perfusion defect salvaged by reperfusion therapy), which was obtained by paired scintigraphic studies performed 7-14 days apart, was the primary endpoint of the study. One-year clinical follow-up was also done.

RESULTS

Salvage index did not differ significantly among patients treated with reduced-dose alteplase plus abciximab (median, 0.41 [25th; 75th percentiles: 0.13; 0.58]) compared to patients who received alteplase (0.26 [0.09; 0.61], p = 0.30). Final infarct size was 16.0% [4.0; 31.0] of the left ventricle in the group with reduced-dose alteplase plus abciximab and 19.4% [7.9; 34.2] of left ventricle in the group with alteplase (p = 0.44). Within a time-to-admission interval of <2 hours, there was a trend for higher values of salvage index in patients who received reduced-dose alteplase plus abciximab compared with patients who received alteplase (0.55 [0.35; 0.73] versus 0.29 [0.11; 0.69], p = 0.15). For time-to-admission intervals > or = 2 hours, no such trend was observed between those who received reduced-dose alteplase plus abciximab or alteplase (0.25 [0.08; 0.48] versus 0.22 [0.08; 0.46], p = 0.79). Major bleeding occurred in 4 patients (5.0%) in the group with reduced-dose alteplase plus abciximab versus 2 patients (3.0%) in the group with alteplase alone (p = 0.58).

CONCLUSION

When used as a general strategy in patients with acute myocardial infarction, adding abciximab to alteplase does not increase significantly the amount of salvaged myocardium as compared with alteplase alone. Combination therapy may offer advantages over thrombolytic agents alone if such therapy is applied within 2 hours from symptom onset; however these data need to be proven by studies of adequate power.

Detection of microvascular injury by evaluating epicardial blood flow in early reperfusion following primary angioplasty

BACKGROUND

In a significant proportion of patients with acute myocardial infarction (AMI), successful opening of the infarct related artery (IRA) does not translate into adequate perfusion at the tissue level. We hypothesised that deterioration of epicardial blood flow in early reperfusion may identify early signs of coronary microvascular injury.

METHODS

In 272 consecutive patients (age 56.9+/-10.4 years) with AMI treated by primary angioplasty (PCI), coronary blood flow (Trombolysis in Myocardial Infarction (TIMI) scale and corrected TIMI frame count (cTFC)) was evaluated before [B], immediately after [O] and 15 min after [O15] opening of the IRA. The sum of ST-segment elevation in standard ECG leads (sigmaST) was measured at [B], at [O15] and 24 h after [C24]. Microvascular injury was assessed by indexes STi(O15)=sigmaST(O15)/sigmaST(B), STi(C24)=sigmaST(C24)/sigmaST(B), and by peak CK-MB release. Coronary flow deterioration (cTFC(DET)) was defined as the difference between cTFC(O15) and cTFC(O).

RESULTS

TIMI-3 flow was achieved in 236 (90.8%) patients at [O]. In the early phase of reperfusion (between [O] and [O15]), TIMI flow deteriorated by >/=1 point in 19 (7.3%) patients despite angiographic optimisation of the PCI result. At [O15] 224 (86.2%) patients had TIMI-3 flow (reflow), 36 (13.8%) patients had TIMI</=2 flow (no-reflow). cTFC(DET) was 30.2+/-16.5 in the no-reflow group but only 7.5+/-4.0 in the reflow group (p<0.001). cTFC(DET) showed a significant correlation with STi(O15) (r=0.63; p<0.001), STi(C24) (r=0.62; p<0.001) and peak CK-MB (r=0.36; p=0.001). In conclusion, we found that an increase in corrected TIMI frame count following successful IRA opening in AMI is an early angiographic indicator of coronary microvascular injury.

Rheolytic thrombectomy with distal filter embolic protection as adjunctive therapies to high-risk saphenous vein graft intervention

Percutaneous intervention of saphenous vein graft (SVG), especially those with heavy atherothrombotic load, presents high risk for distal embolization and no-reflow. Using the distal filters alone may occasionally be disadvantageous because of the large debris burden and the inability to assess the underlying culprit lesions and vessel size accurately. We present a case of intervention of an occluded SVG using a combination of rheolytic thrombectomy and distal filter embolic protection as a pretreatment before stenting. This strategy has the potential to reduce further the risk of no-reflow and to provide visualization for proper assessment of the underlying anatomy especially in clot-laden vessels.

Effectiveness of primary percutaneous coronary intervention compared with that of thrombolytic therapy in elderly patients with acute myocardial infarction

BACKGROUND

Few data exist from a community-based perspective on the relative effectiveness of primary percutaneous coronary intervention (PCI) as compared with thrombolytic therapy (TT) in elderly patients with ST-elevation myocardial infarction (STEMI), particularly in the current era of coronary stents and newer antithrombotic agents.

METHODS

We evaluated data from patients, aged > or =70 years, with STEMI who were enrolled in the Global Registry of Acute Coronary Events study between April 1999, and September 2002.

RESULTS

Of the 2975 elderly patients eligible for reperfusion therapy, 365 (12.7%) underwent primary PCI and 769 (26.7%) received TT. The median delay from hospital arrival to therapy was 105 minutes for primary PCI and 40 minutes for TT. Inhospital complications for primary PCI versus TT included mortality (13.5% vs 14.8%), reinfarction (1.1% vs 5.7%), composite of death or reinfarction (14.3% vs 18.7%), cardiogenic shock (11.3% vs 11.6%), major bleeding (8.6% vs 5.9%), and stroke (1.1% vs 2.8%). After adjustment for baseline differences and propensity score, patients receiving primary PCI showed a lower rate of reinfarction (odds ratio [OR], 0.15; 95% CI, 0.05-0.44) and mortality (OR, 0.62; 95% CI, 0.39-0.96) and the composite of reinfarction or death (OR, 0.53; 95% CI, 0.35-0.79), with no difference in other outcome measures.

CONCLUSION

Our data suggest that, compared with TT, primary PCI is associated with a decrease in reinfarction and mortality, with no change in other outcome measures, in elderly patients with STEMI. These findings from an observational registry require further confirmation in future randomized clinical trial assessing the optimal reperfusion strategy in the elderly cohort with STEMI.

Quantitative estimation of myocardial salvage after primary percutaneous transluminal coronary angioplasty in patients with angiographic no reflow

Angiographic Thrombolysis in Myocardial Infarction (TIMI) flow grade <or=2 after primary percutaneous transluminal coronary angioplasty (PTCA), defined as angiographic no reflow, predicts poor left ventricular functional recovery and survival in patients with acute myocardial infarction (MI). To determine the relation between angiographic coronary flow and myocardial salvage in the acute phase of MI, serial technetium-99m tetrofosmin imaging was performed before, immediately after and 1 month after PTCA in 117 patients. Angiographic no reflow was observed in 23 patients (20%; group 1), while 94 patients did not have angiographic no reflow (group 2). Although there was no significant difference in the defect score before PTCA between the two groups (group 1, 14.4+/-5.7; group 2, 13.5+/-4.6), the defect score immediately after PTCA in group 1 was significantly higher than that in group 2 (group 1, 12.8+/-5.1; group 2, 8.9+/-4.6; P<0.0001). A significantly smaller change in the defect score after PTCA (before minus immediately after PTCA) was observed in group 1 as compared with group 2 (group 1, 1.7+/-2.0; group 2, 4.5+/-2.9; P<0.0001). Twenty patients in group 1 (87%) had impaired myocardial reperfusion (<4 change in the defect score immediately after PTCA), as compared with 36 patients (38%) in group 2; this difference was significant (chi(2)=17.5, P<0.0001). The sensitivity, specificity and accuracy of angiographic no reflow in estimating impaired myocardial reperfusion were 36%, 95% and 67%, respectively. Thus, angiographic no reflow is a highly specific, although not sensitive, marker of impaired myocardial reperfusion immediately after primary PTCA.

Direct infarct artery stenting without predilation and no-reflow in patients with acute myocardial infarction

BACKGROUND

In patients with acute myocardial infarction (AMI), the rate of microvascular embolization and no-reflow promoted by coronary stenting with the use of conventional techniques (CS) appears to be greater than the one that occurs with balloon angioplasty. The minor invasiveness of direct stenting (DS) of the infarct artery without predilation could be expected to reduce embolization in the coronary microvasculature and no-reflow in patients with AMI.

METHODS

In a cohort of 423 consecutive patients with AMI who underwent infarct-artery stenting, we compared CS and DS in terms of angiographic no-reflow rate and 1-month clinical outcome.

RESULTS

At baseline patients who underwent DS (n = 110) had a better risk profile compared with the use of CS (n = 313). The incidence of angiographic no-reflow was 12% in the CS group and 5.5% in the DS group (P =.040). The 1-month mortality rate was 8% in the CS group and 1% in the DS group (P =.008). The mortality rate was 11% in patients with no-reflow and 5.6% in patients with a normal flow. Multivariate analysis showed that age, preprocedure patent infarct artery, and lesion length were related to the risk of no-reflow. In the subset of patients with a target lesion length </=15 mm, the variables independently related to the risk of no-reflow were age, DS, and final balloon inflation pressure.

CONCLUSIONS

DS in patients with AMI may reduce the incidence of angiographic no-reflow, thereby increasing ultimate effective myocardial reperfusion.

Platelet glycoprotein IIb/IIIa-receptor inhibitors in patients with acute coronary syndromes or undergoing percutaneous coronary interventions: a review

BACKGROUND

Over 12.2 million Americans are affected by acute coronary syndromes (ACS) resulting from arterial thrombosis after atherosclerotic plaque rupture. The mechanism of thrombosis is based on the platelet activation pathway, facilitated by expression of the platelet glycoprotein (GP) lIb/Illa receptors. The platelet GP IIb/IIIa-receptor inhibitors represent a new class of drugs, of which abciximab, eptifibatide, and tirofiban have been approved for use in the medical management of ACS and as adjunctive therapy in percutaneous coronary interventions (PCIs).

OBJECTIVE

This article reviews the results of published multicenter, randomized, placebo-controlled, double-blind trials of the efficacy and safety of platelet GP IIb/IIIa-receptor inhibitors in patients with coronary artery disease.

METHODS

To identify articles for this review, a search of MEDLINE for the years 1994 through 2000 was conducted using the key words myocardial ischemia, unstable angina, angioplasty, stent, abciximab, eptifibatide, tirofiban, lamifiban, and platelet aggregation inhibitors. Relevant review articles were consulted as well as reports of clinical studies.

CONCLUSIONS

Three GP IIb/IIIa-receptor inhibitors--abciximab, eptifibatide, and tirofiban-are approved by the US Food and Drug Administration as adjunctive therapy in patients undergoing PCI. Eptifibatide and tirofiban 'are also indicated for the medical management of patients with unstable angina and non-ST-segment-elevation myocardial infarction. The use of GP IIb/IIIa-receptor inhibitors as a component of management with fibrinolytic agents is under investigation. Studies comparing the efficacy of tirofiban and abciximab in patients undergoing planned PCI with intracoronary stent placement are in progress. Until data are available from long-term trials and head-to-head comparisons of these agents, it is not possible to generalize about their overall or comparative efficacy.

Comparative efficacy of primary angioplasty with stent implantation and thrombolysis in restoring basal coronary artery flow in acute ST segment elevation myocardial infarction: quantitative assessment using the corrected TIMI frame count

Following thrombolysis and primary percutaneous transluminal coronary angioplasty (PTCA) for acute ST segment elevation myocardial infarction, basal flow in the culprit artery is known to influence prognosis. The purpose of this study was to determine if differences exist in basal flow in culprit and nonculprit coronary arteries in patients with acute ST segment elevation myocardial infarction who were treated with thrombolysis or primary PTCA with stent implantation. Twenty patients were randomized to thrombolysis (with recombinant tissue plasminogen activator) and 24 to primary PTCA with stent implantation within 3 hours of onset of acute ST segment elevation myocardial infarction. Coronary angiography was performed 90-120 minutes after thrombolysis or immediately after PTCA with stent implantation and again at 18-36 hours after intervention in both groups. Patients who failed to achieve thrombolysis in myocardial infarction (TIMI) grade 2 or 3 flow were excluded. The corrected TIMI frame count was used as the index of basal coronary artery flow. Early after intervention the mean corrected TIMI frame count in the culprit coronary artery was significantly lower in the primary PTCA with stent group (27.4 +/- 7.7 frames) than in the thrombolysis group (39.8 +/- 10 frames, p < 0.001). Eight thrombolysis patients (40%) and 20 primary PTCA patients (83%, p < 0.01) achieved TIMI grade 3 flow early after intervention. By 18-36 hours after intervention there were no significant differences in the mean correct TIMI frame count between the thrombolysis and primary PTCA with stent groups. There were no significant differences in the mean corrected TIMI frame count between these two groups in the nonculprit coronary artery, either early after intervention or at 18-36 hours. In successfully reperfused coronary arteries following acute ST segment elevation myocardial infarction, primary angioplasty with stent implantation reestablished TIMI grade 2 or 3 flow faster and more effectively than thrombolysis did.

Pulse infusion thrombolysis (PIT) for large intracoronary thrombus: preventive effect against the 'no flow' phenomenon in revascularization therapy for acute myocardial infarction

Because large thrombus is a limitation for revascularization in acute myocardial infarction (AMI), the present study evaluated the effectiveness of pulse infusion thrombolysis (PIT) in patients with an AMI with a large (>15 mm) coronary thrombus, focusing on the occurrence of the 'no flow' phenomenon. The retrospective study compared patients treated before (1988-95; Group A, n=74) and after (1996-99; Group B, n=40) the use of PIT, using the following parameters: lesion success (<50% stenosis during 30-min observation), procedural success (lesion success plus TIMI grade 3 flow), procedural no flow (TIMI grade 0 flow during the procedure with 'back and forth movement' of contrast dye after lesion success), persistent no flow (consistent no flow without any flow improvement at the final visualization despite intensive treatment), reocclusion rate and in-hospital death. Group B was significantly better than Group A in procedural success (90% vs 66%; p=0.005), procedural 'no flow' (51% vs 15%; p<0.001), and persistent 'no flow' (34% vs 10%; p<0.05). Subgroup comparison was performed among the following groups: Direct-BA group (n=44): treated with mechanical angioplasty alone; ICT-BA group (n=40): treated with prior intracoronary thrombolysis and angioplasty; and PIT-BA group (n=30): treated with PIT and angioplasty. There were no differences in thrombus length and lesion success among these 3 groups. Procedural success was best achieved in PIT-BA: 97% vs 52% for Direct-BA (p=0.003) and 68% for ICT-BA (p=0.009). Procedural 'no flow' was least in PIT-BA: 50% vs 3.3% for Direct-BA (p=0.003) and 25% vs 3.3% for ICT-BA (p=0.042). Persistent 'no flow' was less frequent in PIT-BA than Direct-BA: 32% vs 3.3% (p=0.009). However, the difference between ICT-BA and Direct-BA was insignificant: 13% vs 3.3% (p=0.53). There were no differences in reocclusion rate and in-hospital death among the 3 subgroups. And there were no differences between Direct-BA and ICT-BA in any parameters. PIT was effective in preventing 'no flow' in the mechanical revasculalization for AMI especially those cases with a large thrombus.

[Coronary angioplasty in the acute myocardial infarction: in which patients is it less likely to obtain an adequate coronary reperfusion?]

INTRODUCTION

In patients with acute myocardial infarction treated with primary angioplasty, the inability to achieve successful coronary reperfusion is associated with higher mortality. The objective of the study was to identify which characteristics may predict a lower angiographic success rate in patients with acute myocardial infarction treated with coronary angioplasty.

PATIENTS AND METHODS

The study population is constituted by the 790 patients with acute myocardial infarction that were treated with angioplasty within the 12 hours after the onset of symptoms from 1991 to 1999 at our institution. A successful angiographic result was considered in presence of a residual stenosis < 50% and a TIMI flow 2 or 3 after the procedure.

RESULTS

A successful angiographic result and a final TIMI 3 flow were achieved in 736 (93.2%) and 652 (82.5%) patients, respectively. In-hospital mortality was higher in patients with angiographic failure than in those with angiographic successful result (48 vs. 10%; p < 0.01). Age under 65 (91 vs. 95%; p = 0.02), non smoking (90 vs. 96%; p < 0,01), previous infarction (87 vs. 94%; p < 0.01), angioplasty after failed thrombolysis (83 vs. 94%; p = 0. 02), cardiogenic shock (80 vs. 95%; p < 0.01), undetermined location (67 vs. 93%; p < 0.01), non-inferior location (92 vs. 96%; p = 0.04), left bundle branch block (64 vs. 94%; p < 0.01), multivessel disease (91 vs. 95%; p = 0.02), left ventricular ejection fraction < 0.40 (89 vs. 97%; p < 0.01), no utilization of coronary stenting (90 vs. 96%; p < 0.01), and use of intraaortic balloon counterpulsation pump (82 vs. 95%; p < 0.01) were associated with a lower angiographic success rate. In the multivariable analysis, the following were independent predictors for angiographic failure: left bundle branch block (odds ratio [OR], 12.95; CI 95%, 3.00-53.90), cardiogenic shock (OR, 4.20; CI 95%, 1.95-8.75), no utilization of coronary stent (OR, 3.44; CI 95%, 1.71-7.37), and previous infarction (OR, 2.82; CI 95%, 1.29-5.90).

CONCLUSIONS

Coronary angioplasty allows a successful coronary recanalization in most patients with acute myocardial infarction. Some basic characteristics, however, may identify some subsets in which a successful angiographic result may be more difficult to obtain.

Microvascular dysfunction in acute myocardial infarction: focus on the roles of platelet and inflammatory mediators in the no-reflow phenomenon

Recent interest has shifted from infarct artery patency to microvascular perfusion in the evaluation of patients with acute myocardial infarction (AMI). Microvascular dysfunction occurs in a substantial proportion of patients, despite aggressive therapy with thrombolytic agents and/or percutaneous mechanical revascularization techniques. Patients with impaired microvascular perfusion after immediate reperfusion therapy have an adverse clinical prognosis. Recent studies have extended our understanding of the pathophysiology of this so-called no-reflow phenomenon, focusing on the critical roles of platelet and inflammatory mediators leading to microvascular obstruction and reperfusion injury. Moving beyond the Thrombolysis in Myocardial Infarction (TIMI) flow grade system, new techniques have been developed to assess microvascular perfusion, including TIMI frame counting, angiographic myocardial perfusion grading, myocardial contrast echocardiography, Doppler flow wire studies, nuclear scintigraphy, and magnetic resonance imaging. Armed with a greater understanding of the primary mediators of microvascular dysfunction, these tools may identify improved therapy directed at optimizing myocardial perfusion in patients with AMI.

Can coronary blood flow velocity pattern after primary percutaneous transluminal coronary angioplasty [correction of angiography] predict recovery of regional left ventricular function in patients with acute myocardial infarction?

BACKGROUND

In the era of primary percutaneous transluminal coronary angioplasty (PTCA), it is important to judge whether myocardium within acute ischemic injury is viable. This study sought to investigate parameters derived from the coronary blood flow velocity spectrum immediately after primary PTCA in patients with acute myocardial infarction and to elucidate the clinical value of coronary blood flow measurement in predicting myocardial viability.

METHODS AND RESULTS

Using a Doppler guidewire, we measured coronary blood flow velocity after successful completion of primary PTCA in 23 consecutive patients with acute anterior myocardial infarction. Regional wall motion was analyzed to estimate anterior wall motion score index (A-WMSI) by echocardiography before PTCA and 1 month after the onset of symptoms. Average systolic peak velocity (ASV) and deceleration time of diastolic flow velocity (DDT) significantly correlated to 1-month A-WMSI (r=-0.54, P=0.007 and r=-0.62, P=0.002, respectively), and optimal cutoff values to predict viable myocardium (defined as 1-month A-WMSI </=2.0) were 6.5 cm/s for ASV and 600 ms for DDT (sensitivity=0.79, specificity=0.89 and sensitivity=0.86, specificity=0.89, respectively). ASV and DDT also correlated weakly to the change in A-WMSI (r=0.46, P=0.03 and r=0.49, P=0.02, respectively).

CONCLUSIONS

Low ASV and rapid DDT of coronary blood flow spectrum immediately after primary PTCA reflects a greater degree of microvascular damage in the risk area. Analysis of coronary blood flow spectrum immediately after primary PTCA by use of a Doppler guidewire is useful in predicting recovery of regional left ventricular function.

Vectorcardiographic evaluation of myocardial infarct size: departure parameters are superior to conventional spatial parameters

To determine whether the departure parameters derived from a "departure loop" of a vectorcardiogram are more accurate than conventional spatial parameters in evaluating myocardial infarct size, 74 patients with first-onset myocardial infarction (MI) were studied. The correlation between the departure parameters (amplitudes in scalar leads of the departure loop) and the percent defect volume of thallium myocardial scintigrams (%DV) was compared with that of the spatial parameters (magnitude, azimuth, and elevation of the original QRS loop). In anteroseptal MI, the amplitude of a 20-msec vector in the z-axis and the azimuth of a 30-msec vector (H30) were significantly correlated with %DV (r=0.783, p<0.001 and r=0.572, p<0.05). In anteroseptal MI with involvement of the lateral wall, the amplitude of a 30-msec vector in the x-axis and H30 showed significant correlation with %DV (r=0.802, p<0.001 and r=0.772, p<0.01). In inferior and inferoposterior MI, the amplitude of a 30-msec vector in the y-axis and the elevation of a 30-msec vector were significantly correlated with %DV (r=0.920, 0.891, p<0.001 and r=0.871, 0.678, p<0.01, respectively). In conclusion, the departure parameters are more accurate than the spatial parameters for evaluation of myocardial infarct size.

Poloxamer-188 as an adjunct to primary percutaneous transluminal coronary angioplasty for acute myocardial infarction

Poloxamer-188 is a surfactant polymer with antithrombotic and hemorheologic properties that make it potentially useful as an adjunct to acute reperfusion strategies. Animal studies and early human studies have documented poloxamer-188 to be effective at improving myocardial salvage when used as an adjunct to intravenous thrombolytic therapy for acute myocardial infarction. The current trial was a prospective pilot study involving 150 patients who were randomized in a 2:1 fashion to a poloxamer-188 infusion for 48-hours versus placebo. The poloxamer-188 infusion was well tolerated subjectively. The only clinically significant laboratory abnormality noted was an elevation in the serum creatinine above 2.0 g/dl in 12% (n = 12) of the 98 poloxamer-188 treated patients versus 1 of the 52 (2%) of the placebo treated patients (p = 0.048). Clinical end points including reinfarction (1% vs 4%), cardiogenic shock (7% vs 6%), and death (9% vs 4%) were statistically similar in the poloxamer-188 and placebo groups, respectively (p = NS). Using quantitative nuclear techniques, final infarct size and myocardial salvage were statistically similar in the poloxamer-188 and placebo groups. Mean left ventricular ejection fractions 1 week post after infarction were 51% +/- 12% in the poloxamer-188 group and 52% +/- 13% in the placebo group (p = NS). Final infarct size, was not altered by the poloxamer- 188 infusion; however, it was significantly correlated with normal perfusion (Thrombolysis in Myocardial Infarction grade 3 flow) in the infarct vessel after angioplasty. This study documented poloxamer-188 to be ineffective as an adjunct to primary angioplasty for acute myocardial infarction and resulted in azotemia in 12% of the patients.