A randomized trial of intravenous tissue plasminogen activator for acute myocardial infarction with subsequent randomization to elective coronary angioplasty

Effect of immediate postoperative intracameral tissue plasminogen activator (tPA) on anterior chamber fibrin formation in dogs undergoing phacoemulsification

OBJECTIVE

To evaluate the postoperative effect of intracameral tPA (alteplase; Activase®, Genentech, San Francisco, CA), administered at immediate conclusion of phacoemulsification, on anterior chamber fibrin formation in dogs.

PROCEDURES

Forty-one dogs (82 eyes) undergoing bilateral phacoemulsification received 25 μg/0.1 mL intracameral tPA in one eye and 0.1 mL unmedicated aqueous vehicle in the contralateral eye immediately after corneal incision closure. Intraocular pressure (IOP) was measured, and severity of anterior chamber fibrin formation, aqueous flare, pigment precipitates on the intraocular lens (IOL) implant, posterior capsular opacification (PCO), and corneal edema were graded at approximately 1 week, 2-3 weeks, 4-6 weeks, 8-12 weeks, and greater than 3 months postoperatively.

RESULTS

Anterior chamber fibrin developed postoperatively in 68.3% of dogs (28/41) and 50% of eyes (41/82). In tPA-treated eyes, 53.7% (22/41) developed fibrin compared to 46.3% of control eyes (19/41). Some degree of postoperative ocular hypertension (POH) occurred in 53.7% of dogs (22/41) and 36.5% of eyes (30/82). In tPA-treated eyes, 34.1% (14/41) experienced POH compared to 39% of control eyes (16/41). Additional intracameral tPA injection was later required in 29.3% of both tPA-treated (12/41) and control eyes (12/41).

CONCLUSIONS

Administration of intracameral tPA at immediate conclusion of canine phacoemulsification had no clinically observable effect on anterior chamber fibrin incidence at any time point. tPA-treated eyes showed no prophylaxis against POH or secondary glaucoma compared to control eyes and received late postoperative tPA injections at the same frequency as control eyes.

Enzymes approved for human therapy: indications, mechanisms and adverse effects

Research and drug developments fostered under orphan drug product development programs have greatly assisted the introduction of efficient and safe enzyme-based therapies for a range of rare disorders. The introduction and regulatory approval of 20 different recombinant enzymes has enabled, often for the first time, effective enzyme-replacement therapy for some lysosomal storage disorders, including Gaucher (imiglucerase, taliglucerase, and velaglucerase), Fabry (agalsidase alfa and beta), and Pompe (alglucosidase alfa) diseases and mucopolysaccharidoses I (laronidase), II (idursulfase), IVA (elosulfase), and VI (galsulfase). Approved recombinant enzymes are also now used as therapy for myocardial infarction (alteplase, reteplase, and tenecteplase), cystic fibrosis (dornase alfa), chronic gout (pegloticase), tumor lysis syndrome (rasburicase), leukemia (L-asparaginase), some collagen-based disorders such as Dupuytren's contracture (collagenase), severe combined immunodeficiency disease (pegademase bovine), detoxification of methotrexate (glucarpidase), and vitreomacular adhesion (ocriplasmin). The development of these efficacious and safe enzyme-based therapies has occurred hand in hand with some remarkable advances in the preparation of the often specifically designed recombinant enzymes; the manufacturing expertise necessary for commercial production; our understanding of underlying mechanisms operative in the different diseases; and the mechanisms of action of the relevant recombinant enzymes. Together with information on these mechanisms, safety findings recorded so far on the various adverse events and problems of immunogenicity of the recombinant enzymes used for therapy are presented.

Intravenous thrombolytic treatment for acute myocardial infarction. Effects of early intervention and early examination

Intravenous thrombolytic treatment (streptokinase or anisoylated plasminogen streptokinase activator complex (APSAC) was given to 50 consecutive patients within 3 hours after onset of symptoms of acute myocardial infarction. Left heart catheterisation with coronary angiography and simultaneous double view left ventriculography were performed approximately 4 hours after start of thrombolytic treatment. This examination showed that the acute infarct-related coronary artery was open in 36 patients (72%) and closed in 14 patients (28%). A higher left ventricular ejection fraction was found among patients with open, than among patients with closed infarct-related artery (58.8% vs. 48.4%, p = 0.05). The group with open artery also had a lower score of regional left ventricular dysfunction (1.7 vs. 2.4, p less than 0.05, on a scale from 0-3). Single, double and triple vessel coronary heart disease was found in 22, 14 and 13 patients respectively. Mean age was lower in the group with single vessel disease as compared to double and triple vessel disease (48.4 years vs. 53.4 and 55.4 years, p less than 0.05 and p less than 0.005). Independently of whether the infarct-related artery was open or closed, there tended to be an inverse correlation between number of diseased vessels and preservation of left ventricular function (statistical significance only for single vessel versus triple vessel disease with respect to score of regional left ventricular dysfunction, 1.8 vs. 2.4, p less than 0.05). These findings suggest that early thrombolytic treatment within 3 hours of onset of symptoms may preserve myocardial tissue during the evolution of acute infarction. Furthermore, a presumably better collateralisation from adjacent coronary arteries without stenoses may be important for myocardial preservation. Finally, early angiographic examination can be performed safely and is a good support for determination of further treatment, which in the actual patients was coronary bypass surgery in 8 cases, transluminal angioplasty, PTCA, in 20 cases, and medical treatment alone in 22 cases.

An early invasive strategy versus ischemia-guided management after fibrinolytic therapy for ST-segment elevation myocardial infarction: a meta-analysis of contemporary randomized controlled trials

BACKGROUND

Although the use of an early invasive strategy among patients with ST-segment elevation myocardial infarctions (STEMI) who are treated initially with fibrinolytic therapy is common, the safety and efficacy of this approach remains uncertain. We performed a meta-analysis to best estimate the benefits and harms of an early invasive strategy in STEMI patients treated initially with full-dose intravenous fibrinolytic therapy, as compared to a traditional strategy of ischemia-guided management.

METHODS

We included contemporary randomized controlled trials, defined a priori as those with >50% stent use during percutaneous coronary intervention (PCI). Outcomes extracted from the published results of eligible trials included all-cause mortality, reinfarction, stroke, and in-hospital major bleeding.

RESULTS

We identified 5 contemporary trials enrolling 1,235 patients who met our inclusion criteria. Of the patients randomized to an early invasive strategy, 86% underwent PCI with 87% receiving stents. Follow-up duration ranged from 30 days to 1 year. An early invasive strategy was associated with significant reductions in mortality (odds ratio [OR] 0.55, 95% CI 0.34-0.90) and reinfarction (OR 0.53, 95% CI 0.33-0.86) compared with ischemia-guided management. There were no significant differences in the risk of stroke (OR 1.31, 95% CI 0.42-4.10) or major bleeding (OR 1.41, 95% CI 0.74-2.69).

CONCLUSIONS

An early invasive strategy after fibrinolytic therapy is associated with significant reductions in mortality and reinfarction. Our results suggest a potentially important role for this strategy in the management of STEMI patients but should be confirmed by large randomized trials.

Heart failure: metabolic derangements and therapeutic rationale

In the USA, over two-thirds of patients with heart failure (HF) are cared for by primary care practitioners exclusively. Significant progress has been made through basic science and clinical research focusing on the prevention of HF via control of known risk factors. There has also been a great deal of progress in both pharmacologic and nonpharmacologic management of the disease. These therapeutic interventions, however, continue to be underutilized, with seemingly inadequate translation of new evidence and updated guidelines (American College of Cardiology/American Heart Association, European Society of Cardiology, Canadian Cardiovascular Society, and Heart Failure Society of America updates in 2005-2006) into clinical practice. In this review, we discuss the pathophysiology of HF in addition to the metabolic derangements and therapeutic rationale surrounding current treatment options, with a particular focus on the interventions that have been shown and recommended in updated guidelines to prevent the disease or halt its progression.

Percutaneous Coronary Intervention After Fibrinolysis

OBJECTIVES

We performed a meta-analysis of randomized trials that enrolled ST-segment elevation myocardial infarction patients treated with fibrinolysis to assess the potential benefits of: 1) rescue percutaneous coronary intervention (PCI) versus no PCI; 2) systematic and early (< or =24 h) PCI versus delayed or ischemia-guided PCI; 3) fibrinolysis-facilitated PCI versus primary PCI alone.

BACKGROUND

The impact of PCI strategies after fibrinolysis on mortality or reinfarction remains to be established.

METHODS

The meta-analysis was performed using the odds ratio (OR) as the parameter of efficacy with a random effect model. Fifteen randomized trials (5,253 patients) were selected. The primary end point was mortality or the combined end point of death or reinfarction.

RESULTS

Rescue PCI for failed fibrinolysis reduced mortality (6.9% vs. 10.7%) (OR, 0.63; 95% confidence interval [CI], 0.39 to 0.99; p = 0.055) and the rate of death or reinfarction (10.8% vs. 16.8%) (OR, 0.60; 95% CI, 0.41 to 0.89; p = 0.012) compared with a conservative approach. Systematic and early PCI performed during the "stent era" led to a nonsignificant reduction in mortality compared with delayed or ischemia-guided PCI (3.8% vs. 6.7%) (OR, 0.56; 95% CI, 0.29 to 1.05; p = 0.07) and to a 2-fold reduction in the rate of death or reinfarction (7.5% vs. 13.2%) (OR, 0.53; 95% CI, 0.33 to 0.83; p = 0.0067). This benefit contrasted with a nonsignificant increase in the rate of both mortality (5.5% vs. 3.9%, p = 0.33) or death or reinfarction (9.6% vs. 5.7%, p = 0.06) observed in the "balloon era." Fibrinolysis-facilitated PCI was associated with more reinfarction as compared with primary PCI alone (5.0% vs. 3.0%) (OR, 1.68; 95% CI, 1.12 to 2.51; p = 0.013) without significant impact on mortality (OR, 1.30; 95% CI, 0.92 to 1.83; p = 0.13).

CONCLUSIONS

Our findings support rescue PCI and systematic and early PCI after fibrinolysis. However, the current data do not support fibrinolysis-facilitated PCI in lieu of primary PCI alone.

Clinical prognosis, pre-existing conditions and the use of reperfusion therapy for patients with ST segment elevation acute myocardial infarction

BACKGROUND

Some evidence-based therapies are underused in patients with a poor prognosis despite the fact that the survival gains would be highest among such patient subgroups. The extent to which this applies for acute, life-saving therapies is unknown. The impact of prognostic characteristics and pre-existing conditions on the use of reperfusion therapy among eligible patients with acute ST segment elevation myocardial infarction is examined.

METHODS

Of 2829 acute myocardial infarction patients prospectively identified in 53 acute care hospitals across Ontario, 987 presented with ST segment elevation within 12 h of symptom onset and without any absolute contraindications to reperfusion therapy. The baseline prognosis for each patient was derived from a validated risk-adjustment model of 30-day mortality. Multiple logistical regression was used to examine the relationships among reperfusion therapy, prognosis and the number of pre-existing chronic conditions after adjusting for factors such as age, sex, time since symptom onset and socioeconomic status.

RESULTS

Of the 987 appropriate candidates, 725 (73.5%) received reperfusion therapy (70.8% fibrinolysis, 2.6% primary angioplasty). The adjusted odds ratio of reperfusion therapy fell 4% with each 1% increase in baseline risk of death (adjusted OR 0.96, 95% CI 0.92 to 1.00, P=0.04) and fell 18% with each additional pre-existing condition (adjusted OR 0.82, 95% CI 0.76 to 0.90, P<0.001). The number rather than the type of pre-existing conditions inversely correlated with the use of reperfusion therapy. While the impact of baseline risk and pre-existing conditions was additive, pre-existing conditions exerted a greater impact on the nonuse of reperfusion therapy than did baseline risk.

CONCLUSIONS

A treatment-risk paradox is demonstrable even within a cohort of lower risk patients with ST segment elevation myocardial infarction. These findings are consistent with the view that these clinical decisions are more likely to be attributable to concerns about patient frailty or side effects than to a misunderstanding of treatment benefits.

Out-patient management of chronic heart failure

Chronic heart failure is a clinical syndrome associated with an ominous long-term prognosis and major economic consequences for Western societies. In recent years, considerable progress has been made in the pharmacological management of heart failure, and several treatments have been confirmed to confer survival and symptomatic benefits. However, pharmaceuticals remain underutilised, and the combination of several different drugs present challenges for their optimal prescription, requiring a thorough knowledge of potential side effects and complex interactions. This article reviews in detail the evidence pertaining to the out-patient pharmacological management of chronic heart failure, and offers recommendations on the use of various drugs in complex clinical conditions, or in areas of ongoing controversy.

Early and long-term outcome of elective stenting of the infarct-related artery in patients with viability in the infarct-area: Rationale and design of the Viability-guided Angioplasty after acute Myocardial Infarction-trial (The VIAMI-trial)

Background

Although percutaneous coronary intervention (PCI) is becoming the standard therapy in ST-segment elevation myocardial infarction (STEMI), to date most patients, even in developed countries, are reperfused with intravenous thrombolysis or do not receive a reperfusion therapy at all. In the post-lysis period these patients are at high risk for recurrent ischemic events. Early identification of these patients is mandatory as this subgroup could possibly benefit from an angioplasty of the infarct-related artery.

Since viability seems to be related to ischemic adverse events, we initiated a clinical trial to investigate the benefits of PCI with stenting of the infarct-related artery in patients with viability detected early after acute myocardial infarction.

Methods

The VIAMI-study is designed as a prospective, multicenter, randomized, controlled clinical trial. Patients who are hospitalized with an acute myocardial infarction and who did not have primary or rescue PCI, undergo viability testing by low-dose dobutamine echocardiography (LDDE) within 3 days of admission. Consequently, patients with demonstrated viability are randomized to an invasive or conservative strategy. In the invasive strategy patients undergo coronary angiography with the intention to perform PCI with stenting of the infarct-related coronary artery and concomitant use of abciximab. In the conservative group an ischemia-guided approach is adopted (standard optimal care).

The primary end point is the composite of death from any cause, reinfarction and unstable angina during a follow-up period of three years.

Conclusion

The primary objective of the VIAMI-trial is to demonstrate that angioplasty of the infarct-related coronary artery with stenting and concomitant use of abciximab results in a clinically important risk reduction of future cardiac events in patients with viability in the infarct-area, detected early after myocardial infarction.

Failed reperfusion after thrombolytic therapy: recognition and management

BACKGROUND

Failed reperfusion after thrombolysis occurs in as many as 30% of patients with acute myocardial infarction (MI). Furthermore, some patients have incomplete tissue perfusion despite reperfusion of the infarct-related artery. Close assessment of the efficacy of thrombolytic administration in people with evolving acute MI is necessary, particularly with regard to myocardial perfusion status, because some patients may benefit from incremental pharmacologic or invasive reperfusion strategies.

PURPOSE AND METHOD

This article reviews a number of strategies to assess infarct-related artery patency and myocardial tissue perfusion. These include coronary angiography, continuous ST-segment monitoring, serial electrocardiography, obtaining serial serum biochemical markers of myocardial necrosis, monitoring for reperfusion arrhythmias, and assessment of changes in chest pain intensity.

CONCLUSION

The early detection of failed reperfusion is critical if incremental strategies to enhance myocardial salvage are to be considered. Continuous ST-segment monitoring is a relatively inexpensive, reliable, and accurate tool for assessing real-time myocardial perfusion.

Predictors of left ventricular function after acute myocardial infarction: effects of time to treatment, patency, and body mass index: the GUSTO-I angiographic experience

BACKGROUND

Despite the significant survival benefit associated with successful reperfusion therapy for acute myocardial infarction, global indices of outcome left ventricular function, such as ejection fraction, have often demonstrated little or no improvement. Although these measurements are confounded by numerous clinical, physiologic, and angiographic variables, no comprehensive analysis of this issue in a large series of patients is available. We used the Global Utilization of Streptokinase and Tissue Plasminogen Activator for Occluded Coronary Arteries (GUSTO-I) database to better understand this phenomenon by determining independent predictors of left ventricular function and their interplay with regard to outcome ventricular function and improvement in function during the initial postinfarction week.

METHODS

Ninety-minute and 5- to 7-day posttreatment global and regional indices derived from left ventriculograms were analyzed from a population of 676 patients. These observations were combined with clinical data to describe independent determinants of ventricular function outcome.

RESULTS

Clinical factors predictive of global and regional ventricular function as well as improvement in function between 90 minutes and 5 to 7 days included time to treatment, early infarct-related artery flow grade, and body mass index. These same factors contribute significantly to compensatory hyperkinesis of the noninfarct zone, which is critical to maintenance of global ventricular function during this time period.

CONCLUSIONS

The ventricular function benefits of early complete reperfusion after myocardial infarction are readily demonstrable after adjustment for multiple covariables and include (1) maintenance of global ventricular function and (2) prevention or delay in ventricular dilatation.

Cardioprotective effects of the Na(+)/H(+) exchange inhibitor cariporide in patients with acute anterior myocardial infarction undergoing direct PTCA

BACKGROUND

Activation of Na(+)/H(+) exchange in myocardial ischemia and/or reperfusion leads to calcium overload and myocardial injury. Experimental studies have shown that Na(+)/H(+) exchange inhibitors can attenuate Ca(2+) influx into cardiomyocytes. We therefore performed a multicenter, randomized, placebo-controlled clinical trial to test the hypothesis that inhibition of Na(+)/H(+) exchange limits infarct size and improves myocardial function in patients with acute anterior myocardial infarction (MI) treated with direct PTCA.

METHODS AND RESULTS

One hundred patients were randomized to receive placebo (n=51) or a 40-mg intravenous bolus of the Na(+)/H(+) exchange inhibitor cariporide (HOE 642) (n=49) before reperfusion. Global and regional left ventricular functions were analyzed by use of paired contrast left ventriculograms performed before and 21 days after PTCA and myocardial enzymes (ie, creatine kinase ¿CK, CK-MB, and LDH) as markers for myocardial tissue injury were evaluated. At follow-up, the ejection fraction was higher (50% versus 40%; P<0.05) and the end-systolic volume was lower (69.0 versus 97.0 mL; P<0.05) in the cariporide group. Significant improvements in some indices of regional wall motion abnormalities were observed, such as the percentage of chords with hypokinesis < -2 SD (P=0.045) and the severity of hypokinesis in the border zone of the infarct region (P=0.052). In addition, CK, CK-MB, or LDH release was significantly reduced in the cariporide patients.

CONCLUSIONS

Our findings suggest that inhibition of Na(+)/H(+) exchange by cariporide may attenuate reperfusion injury and thereby improve the recovery from left ventricular dysfunction after MI.

Physicians' Use of Heparin Following Thrombolytic Therapy: An International Perspective

Background: The current prevalence, timing, and route of heparin use after thrombolytic therapy for acute myocardial infarction both within and outside the United States (U.S.) have not been extensively studied. Method: An 18-item questionnaire was mailed to cardiologists and emergency medicine practitioners in the U.S. and to physicians in 5 countries considering participation in an international trial of thrombolytic therapy. Results: Almost all used some form of heparin after recombinant tissue-plasminogen activator; 8% withheld heparin after streptokinase. Non-U.S. physicians used subcutaneous heparin more frequently than did U.S. physicians (26% vs. 4%). Time to heparin initiation varied greatly. Most physicians used the activated partial thromboplastin time to monitor anticoagulation, although there was little consensus about the appropriate way to determine the efficacy of heparin therapy. Conclusions: This survey shows considerable disagreement about the preferred administration of heparin among physicians treating patients with myocardial infarction. This lack of agreement reflects uncertainty about how heparin therapy should be used. When the results of well-designed clinical trials examining the optimal dosing, timing, and monitoring of heparin therapy have been published, perhaps the clinical community can reach a consensus.

Magnetic resonance imaging in acute myocardial infarction

Advances in magnetic resonance imaging (MRI) have led to more widespread utilization of this diagnostic imaging modality in the diagnosis of coronary artery disease. With MRI, the complexity and heterogeneity of myocardial infarcts can be demonstrated. By using this technique, much insight has been gained into the pathophysiologic mechanisms of acute coronary thrombosis and reperfusion. MRI has significant diagnostic potential, particularly if one can combine studies of myocardial function, perfusion, and sodium metabolism with the noninvasive assessment of coronary anatomy and epicardial coronary artery blood flow.

Early referral for intentional rescue PTCA after initiation of thrombolytic therapy in patients admitted to a community hospital because of a large acute myocardial infarction

BACKGROUND

If no in-house facilities for percutaneous transluminal coronary angioplasty (PTCA) are present, thrombolytic therapy is the treatment of choice for acute myocardial infarction (AMI). A few studies have shown benefit from rescue PTCA in patients directly admitted to centers with PTCA facilities. The obvious question arises whether patients with AMI initially admitted to a community hospital can benefit from early transfer for intentional rescue PTCA.

METHODS AND RESULTS

One hundred sixty-five patients were transferred early for intentional rescue PTCA from a community hospital at a distance of 20 miles. On arrival at the angioplasty center, bedside markers were used to determine reperfusion. In case of obvious reperfusion, no invasive procedure was done; otherwise, coronary angiography and rescue PTCA, if necessary, was performed. During transfer, 1 (1%) patient died and 15 (9%) patients had arrhythmic or hemodynamic problems. Median time delay between onset of chest pain and arrival at the community hospital and the PTCA center was 61 minutes (range 0 to 413) and 150 minutes (range 28 to 472), respectively. In 66 (40%) patients, reperfusion was diagnosed by noninvasive reperfusion criteria on arrival at the PTCA center (group 1). Ninety-eight (59%) patients without evident noninvasive criteria of reperfusion underwent angiography 187 median minutes after the onset of chest pain. Forty-one (25%) patients had Thrombolysis In Myocardial Infarction grade 3 flow, and no further intervention was performed (group 2). In the remaining 57 (35%) patients, rescue PTCA was performed, which was successful in 96% (group 3). In-hospital mortality rate was lowest in group 1 compared with the other 2 groups (0% vs 7% vs 11%; P <.05). Reinfarction was highest in group 1 compared with the other groups (17% vs 5% vs 2%; P <.01). No significant differences were found in coronary artery bypass grafting, stroke, or bleeding complications. The 1-year follow-up data showed low revascularization rates; 2 (1%) patients died after discharge from the hospital.

CONCLUSIONS

Early transfer of patients with large AMI for intentional rescue PTCA can be done with acceptable safety and is feasible within therapeutically acceptable time limits and results in additional early reperfusion in 33% of patients. A large, randomized, multicenter trial is needed to compare efficacy of intravenous thrombolytic treatment in a community hospital versus early referral for either rescue or primary PTCA.

Prognostic significance of ST segment shift early after resolution of ST elevation in patients with myocardial infarction treated with thrombolytic therapy: the GUSTO-I ST Segment Monitoring Substudy

OBJECTIVES

We sought to study the relation between recurrent ST segment shift within 6 to 24 h of initial resolution of ST elevation after thrombolytic therapy and 30-day and 1-year mortality.

BACKGROUND

Rapid and stable resolution of ST segment elevation in relation to thrombolytic therapy in patients with an acute myocardial infarction is an indicator of culprit artery patency. Whether recurrence of ST segment shift during continuous ST monitoring after initial resolution is related to poor prognosis has not been studied.

METHODS

ST segment monitoring was performed within 30 min after thrombolytic therapy for acute myocardial infarction. The predictive value of a new ST segment shift (assessed as > or = 0.1-mV deviation from the baseline) 6 to 24 h after thrombolytic therapy was studied with respect to 30-day and 1-year mortality.

RESULTS

Of 734 patients, 243 had a new ST segment shift (33%). The 30-day mortality rate in patients with an ST shift (7.8%) was significantly higher than that in patients without an ST shift (2.25%, p = 0.001), as was the 1-year mortality rate (10.3% vs. 5.7%, respectively, p = 0.025). Multivariable analysis revealed an independent predictive value of ST shift with respect to 30-day mortality (p = 0.008), even after consideration of multiple clinical risk factors in the overall Global Utilization of Streptokinase and TPA for Occluded Coronary Arteries (GUSTO)-I mortality model (p = 0.0001). Moreover, the duration of the ST shift bore a direct relation with 1-year mortality (p = 0.008).

CONCLUSIONS

Detection of ST segment shift early after thrombolytic therapy for acute myocardial infarction is a simple, noninvasive means of identifying patients at high risk and is superior to other commonly assessed clinical risk factors. Thus, patients with a new ST shift after the first 6 h, but within 24 h, represent a high risk group that may benefit from more aggressive intervention, whereas patients without evidence of an ST shift represent a low risk subgroup.

Prognostic significance of microvascular obstruction by magnetic resonance imaging in patients with acute myocardial infarction

BACKGROUND

The extent of microvascular obstruction during acute coronary occlusion may determine the eventual magnitude of myocardial damage and thus, patient prognosis after infarction. By contrast-enhanced MRI, regions of profound microvascular obstruction at the infarct core are hypoenhanced and correspond to greater myocardial damage acutely. We investigated whether profound microvascular obstruction after infarction predicts 2-year cardiovascular morbidity and mortality.

METHODS AND RESULTS

Forty-four patients underwent MRI 10 +/- 6 days after infarction. Microvascular obstruction was defined as hypoenhancement seen 1 to 2 minutes after contrast injection. Infarct size was assessed as percent left ventricular mass hyperenhanced 5 to 10 minutes after contrast. Patients were followed clinically for 16 +/- 5 months. Seventeen patients returned 6 months after infarction for repeat MRI. Patients with microvascular obstruction (n = 11) had more cardiovascular events than those without (45% versus 9%; P=.016). In fact, microvascular status predicted occurrence of cardiovascular complications (chi2 = 6.46, P<.01). The risk of adverse events increased with infarct extent (30%, 43%, and 71% for small [n = 10], midsized [n = 14], and large [n = 14] infarcts, P<.05). Even after infarct size was controlled for, the presence of microvascular obstruction remained a prognostic marker of postinfarction complications (chi2 = 5.17, P<.05). Among those returning for follow-up imaging, the presence of microvascular obstruction was associated with fibrous scar formation (chi2 = 10.0, P<.01) and left ventricular remodeling (P<.05).

CONCLUSIONS

After infarction, MRI-determined microvascular obstruction predicts more frequent cardiovascular complications. In addition, infarct size determined by MRI also relates directly to long-term prognosis in patients with acute myocardial infarction. Moreover, microvascular status remains a strong prognostic marker even after control for infarct size.

Prevalence of spontaneous reperfusion and associated myocardial salvage in patients with acute myocardial infarction

This study sought to determine the prevalence of spontaneous reperfusion of an infarct-related artery (IRA) and associated myocardial salvage in the absence of thrombolysis or angioplasty. Twenty-one patients with acute myocardial infarction received only heparin and aspirin. At a median of 18 hours after presentation, 12 patients (57%) had angiographic patency of the IRA. Technetium-99m sestamibi was injected acutely on presentation and again at hospital discharge. Acute and final perfusion defect sizes were measured. Their difference, myocardial salvage, was calculated along with salvage index (myocardial salvage/acute defect). Comparing patients with a patent versus occluded IRA, myocardium at risk was similar (16% +/- 12% vs 12% +/- 9% left ventricle, p = NS); however, myocardial salvage (9% +/- 9% vs -2% +/- 7% left ventricle, p = 0.01), and salvage index (0.62 +/- 0.37 vs 0.19 +/- 0.33, p = 0.01) were greater in patients with spontaneous reperfusion. Resolution of chest pain was greater in patients with a patent IRA (100% vs 55%, p = 0.003). Spontaneous reperfusion of the IRA occurs frequently in patients with acute myocardial infarction and is associated with significant myocardial salvage.

Delayed percutaneous transluminal coronary angioplasty after acute myocardial infarction

The value of delayed percutaneous transluminal coronary angioplasty (> 12 h from admission or after thrombolytic therapy) following acute myocardial infarction is controversial. We compared the short- and long-term prognosis of 1940 consecutive patients after acute myocardial infarction, of whom 188 underwent delayed percutaneous transluminal coronary angioplasty. Delayed percutaneous transluminal coronary angioplasty was more frequently done in patients treated with thrombolysis (12%) than among patients excluded from thrombolytic therapy (8%; P=0.005). Patients in the delayed percutaneous transluminal coronary angioplasty group were younger, included more men and smokers and had less in-hospital complications in comparison to patients who did not undergo delayed percutaneous transluminal coronary angioplasty. The crude 30-day and 1-year mortality rates were 3 and 6% among patients who underwent percutaneous transluminal coronary angioplasty vs. 14 and 21% (P<0.01 for each) among those without percutaneous transluminal coronary angioplasty, respectively. After multivariate analysis adjusted for confounding factors, delayed percutaneous transluminal coronary angioplasty was associated with 65 (RR=0.35; 90% CI 0.14-0.88) and 50% (RR=0.50; 90% CI 0.27-0.92) mortality risk reduction after 30 days and 1 year, respectively. In conclusion, delayed percutaneous transluminal coronary angioplasty applied to selected post-myocardial infarction patients upon clinical indication is safe and beneficial for the treatment of acute myocardial infarction in the community.

Pharmacotherapeutics of Biotechnology-Derived Products

Biotechnology has contributed to important advances in the healthcare field. Products include various hormones, enzymes, cytokines, vaccines, and monoclonal antibodies, with use in diverse therapeutic areas. The majority of approved biotechnology-derived therapeutic products are recombinant proteins. Many have orphan drug status and, therefore, are used in relatively small patient populations. Newer generation biotechnology products are likely to include small molecules, gene therapy products, and increased numbers of vaccines and monoclonal antibody products. Biotechnology provides the means to develop diverse, innovative, and effective approaches to the prevention, treatment, and cure of human disease.

Clinical perspectives on the use of composite endpoints

Although mortality is the most important endpoint in evaluating new regimens, insistence on its use as the only endpoint in clinical trials can require that thousands of patients be studied. Accordingly, composite endpoints have been increasingly used to increase the overall event rate and thereby reduce the number of patients needed for the trial. For use as part of composite endpoint, nonfatal endpoints should be clinically meaningful, i.e., related to an adverse subsequent prognosis. In acute myocardial infarction (MI), several intermediate endpoints in the well-described pathophysiology of acute MI have been correlated with an adverse long-term outcome: recurrent MI, new onset congestive heart failure or cardiogenic shock, left ventricular dysfunction, large infarct size, and failure to achieve early patency of the infarct-related artery. Furthermore, in acute MI, new therapies that improve these nonfatal endpoints also improve mortality, thereby validating this approach. Once this link is established, such nonfatal endpoints can be validly used in evaluating new therapies. Note, however, if this link has not been made (that mortality is reduced when there is a reduction in the nonfatal endpoint), as in the case of suppression of ventricular premature complexes with antiarrhythmic therapy, the nonfatal endpoint cannot be used validly. Thus, appropriately designed and validated composite endpoints can provide a valid means of testing new treatments in a smaller trial than one using mortality alone. Their use should allow testing of a greater number of new regimens, thereby allowing more rapid progress toward improving the clinical outcome of patients.

Approaches to informed consent

Informed consent (IC) is an indicator, or a pivotal point, in broader and more fundamental questions dealing with the way clinical experimentation and, more specifically, randomized controlled trials (RCTs) relate to routine clinical practice; the rules that characterize the doctor-patient relationship; the self-perception of medicine with respect to its capacity, duty, and autonomy in the production of new knowledge; and the role of medicine in society. The asymmetry of knowledge and power that characterizes the usual relationship between care providers and patients does not resolve when something experimental enters the relationship. The real world of clinical investigation is not uniformly distinct from clinical practice. Experimentation is more appropriately considered a continuum with respect to appropriate or recommended care. Fundamental patient rights come first and are more binding than compliance with procedures and regulations. The view that IC is the most important component of the "ethical" aspects of experimentation is highly misleading. The responsibility to foster well-informed decisions shapes the contents, the timing, the validity, and the credibility of IC. Documented, evaluable decisions are the natural substitute for individual IC when the patient is not able to handle information autonomously. Positive examples of IC practices and approaches suggest that IC may be important in improving the way medicine responds to its responsibilities and communicates with society.

Revisiting reperfusion therapy in inferior myocardial infarction

Although thrombolytic therapy for acute myocardial infarction (MI) is recommended without regard for infarct location, treatment results are less impressive for inferior than for anterior MI because the amount of myocardium at risk is smaller and less strategically located, and the mortality risk is lower. Whereas the risks associated with anterior MI are relatively constant, high risk subsets of patients with an inferior MI can be identified by simple electrocardiographic criteria, including left precordial ST segment depression, complete atrioventricular heart block and right precordial ST segment elevation. Unfortunately, none of the placebo-controlled, randomized trials have analyzed the benefit of thrombolytic therapy for inferior MI in high risk versus low risk subsets. Thrombolytic therapy should be more successful in reducing infarct size and decreasing mortality in high risk patients with an inferior MI. Thrombolytic therapy may not decrease hospital mortality in low risk patients (baseline risk 2% to 4%) or those with symptom duration > 6 h. Whereas it is arguable whether coronary angioplasty is superior to thrombolytic therapy in anterior MI, there are no mortality data to support using angioplasty as a primary or rescue reperfusion strategy instead of thrombolytic therapy in inferior MI, unless thrombolytic contraindications are present or the patient is in cardiogenic shock.

Clinical characteristics and long-term outcome of patients in whom congestive heart failure develops after thrombolytic therapy for acute myocardial infarction: development of a predictive model

Ischemic heart disease is the most common cause of congestive heart failure, which often begins after acute myocardial infarction. To better delineate the clinical characteristics and outcomes of patients in whom congestive heart failure develops after acute myocardial infarction in the thrombolytic era, we prospectively evaluated patients enrolled in six of the TAMI trials. The study cohort comprised 1619 consecutive patients who had at least 1 mm of ST-segment elevation in two contiguous electrocardiographic leads within 6 hours of the onset of acute myocardial infarction and who received intravenous thrombolytic therapy. We prospectively collected clinical characteristics, baseline demographics, acute and 1-week angiographic variables, and in-hospital and 1-year outcome data. We performed stepwise multivariable regression analysis to determine the noninvasive and invasive predictors of the development of in-hospital congestive heart failure. Congestive heart failure developed in 301 patients in the hospital (19% of 1521 patients admitted were not in heart failure). These patients were likely to be older and female, have diabetes mellitus and previous myocardial infarction, and have an anterior wall myocardial infarction. On acute angiography, they had lower ejection fractions and a higher incidence of multivessel disease. Patency at 90 minutes was lower in the patients with congestive heart failure, and acute mitral regurgitation occurred in 1.6% versus 0.21% of patients without congestive heart failure. Patients with congestive heart failure had higher mortality, more in-hospital complications, and longer hospitalizations. At 1-year follow up, 21% of the patients in whom congestive heart failure developed had died versus 5% in the group without congestive heart failure. Predictors of new congestive heart failure included increased age, anterior wall myocardial infarction, lower pulse pressure and systolic blood pressure, diabetes mellitus, and the presence of rales on admission. The acute angiographic variables of reduced ejection fraction, increased number of diseased vessels, and attempted percutaneous intervention improved the concordance of the predictive model by 6%. Congestive heart failure remains a common clinical problem after acute myocardial infarction and is associated with a twofold increase in in-hospital morbidity and a fourfold increase in in-hospital and 1-year mortality. The development of congestive heart failure in the hospital can be predicted from noninvasive and invasive baseline characteristics. We present a simple table to predict congestive heart failure from baseline characteristics and invasive information.

Further ST elevation at reperfusion by direct percutaneous transluminal coronary angioplasty predicts poor recovery of left ventricular systolic function in anterior wall AMI

Some patients with acute myocardial infarction (AMI) develop further ST elevation at reperfusion by percutaneous transluminal coronary angioplasty (PTCA). This study reports the ST deviation at reperfusion by direct PTCA in relation to the clinical factors and the recovery of left ventricular (LV) systolic function. Fifty-two patients with anterior wall AMI were treated with direct PTCA. They were classified into the following 3 groups according to the change in ST elevation at reperfusion: increase of > or = 20% (ST reelevation); reduction of > or = 20% (ST resolution); and the other (ST no change). Angina pectoris preceding AMI occurred less often in the ST reelevation group (ST reelevation group, 38%; ST no change group, 81%; ST resolution group, 70%; p < 0.05). Recovery of LV ejection fraction during the first month after direct PTCA was significantly poor in the ST reelevation group in contrast to the ST resolution group (ST reelevation group, -6.3 +/- 13%; ST no change group, 18 +/- 20%; ST resolution group, 45 +/- 29%; p < 0.0001). The change in ST elevation at reperfusion was an index predicting the recovery of LV systolic function in the reperfusion by direct PTCA.

Thrombolytic therapy for patients with prior percutaneous transluminal coronary angioplasty and subsequent acute myocardial infarction. GUSTO-I Investigators. Global Utilization of Streptokinase and t-PA for Occluded Coronary Arteries

Our purpose was to evaluate the outcomes of patients with prior coronary angioplasty who underwent thrombolysis for new acute myocardial infarction (AMI) in the Global Utilization of Streptokinase and t-PA for Occluded Coronary Arteries-I trial. Baseline characteristics and clinical outcomes were compared between patients with (n = 1,647) and without (n = 39,150) previous angioplasty. The relations among prior angioplasty, clinical outcomes, and treatment effects were examined with logistic regression modeling. Patients with previous angioplasty tended to be younger and presented sooner after symptom onset, but had more multivessel disease and lower ejection fractions. Unadjusted mortality was significantly lower in the prior-angioplasty group at 24 hours (1.8% vs 2.7%, p = 0.03) and 30 days (5.6% vs 7.0%, p = 0.036). Although most of the survival advantage was due to low-risk characteristics in this group (lower age and heart rate and fewer anterior wall AMIs), prior angioplasty remained a weak but independent predictor of survival. Recurrent ischemia and reinfarction occurred more often in the prior-angioplasty group, as did bypass surgery (12.2% vs 8.5%) and repeat angioplasty (34.5% vs 21.4%). Patients with prior angioplasty and prior AMI had lower 30-day mortality than those with prior infarction alone (6.3% vs 12.6%, p < 0.01). Treatment effects on 30-day mortality were similar among patients with prior angioplasty (odds ratio 1.2 for accelerated tissue-plasminogen activator v. combined streptokinase arms, 95% confidence interval 0.73 to 1.9). Patients with prior angioplasty who present with AMI have fewer in-hospital adverse events and lower 30-day mortality than those without such a history.

Stress radionuclide studies after acute myocardial infarction: changes with revascularization

BACKGROUND

Successful revascularization of ischemic asynergic myocardium should be followed by improvement in contractile function. However, a clear improvement is not always observed. Assessment of contractile reserve may allow a better evaluation of procedural results.

METHODS AND RESULTS

To assess the changes in global and regional left ventricular ejection fraction (EF), as well as the contractile reserve after revascularization, equilibrium radionuclide angiography was performed in 16 patients with acute myocardial infarction who had periinfarct redistribution (observed in stress-rest-reinjection thallium single-photon emission computed tomography). Regional EF was defined in the asynergic region at rest, which corresponded to the infarct plus periinfarct areas. Both thallium single-photon emission computed tomography and equilibrium radionuclide angiography were performed at rest and during stress with dobutamine, up to a maximal dose of 40 micrograms/kg/min. The same studies were repeated 8 +/- 6 months after successful revascularization (nine coronary angioplasties and seven bypass procedures). After intervention, the thallium defect score decreased significantly at rest and during stress. Global EF changed from 45% +/- 10% to 47% +/- 11% (difference not significant) at rest and from 49% +/- 12% to 63% +/- 13% (p = 0.0001) at peak stress. Regional EF changed from 27% +/- 8% to 35% +/- 18% (p = 0.03) at rest and from 29% +/- 10% to 56% +/- 21% (p = 0.0001) at peak stress.

CONCLUSIONS

In patients with asynergy caused by periinfarct ischemia, there can be an increase in regional but not global EF at rest after revascularization. However, both parameters improve at peak dobutamine dose. This indicates an improvement in contractile reserve.

The outcome of patients with acute myocardial infarction ineligible for thrombolytic therapy. Israeli Thrombolytic Survey Group

PURPOSE

The aim of this study was to determine the proportion of patients with acute myocardial infarction (AMI) excluded from thrombolytic therapy on a national basis and to evaluate the prognosis of these patients by reasons of ineligibility and according to the alternative therapies that they received during hospitalization.

PATIENTS AND METHODS

During a national survey, 1,014 consecutive patients with AMI were hospitalized in all the 25 coronary care units operating in Israel.

RESULTS

Three hundred and eighty-three patients (38%) were treated with a thrombolytic agent and included in the GUSTO study. Ineligible patients for GUSTO were treated: (1) without any reperfusion therapy (n = 449), (2) by mechanical revascularization (n = 97), or (3) given 1.5 million units of streptokinase (n = 85) outside of the GUSTO protocol. The inhospital and 1-year post-discharge mortality rates were 6% and 2% in patients included in the GUSTO study; 6% and 5% in those mechanically reperfused; 15% and 10% in those treated with thromoblysis despite ineligibility for the GUSTO trial, and 15% and 13% among patients not treated with any reperfusion therapy.

CONCLUSIONS

Ineligibility for thrombolysis among patients with AMI remains high. Patients ineligible for thrombolysis according to the GUSTO criteria, but nevertheless treated with a thrombolytic agent were exposed to an increased risk.

Management of spinal epidural hematoma after tissue plasminogen activator. A case report

STUDY DESIGN

This case report illustrates a patient with a spontaneous epidural hematoma after tissue plasminogen activator therapy who presented 10 days after the incident with a resolving Brown-Sèquard syndrome.

OBJECTIVES

The treatment of this patient involves the principles of conservative follow-up directed by an improving examination and an understanding of the pathophysiology of coagulopathy-induced spontaneous epidural bleeds.

SUMMARY OF BACKGROUND DATA

The use of tissue plasminogen activator therapy for thrombolysis in patients with early acute myocardial infarction is becoming increasingly routine. Use is limited most significantly by bleeding complications. Recently, several groups have drawn attention to the neurologic complications associated with intracranial hemorrhage after tissue plasminogen activator therapy. Spontaneous spinal epidural hemorrhage has, by comparison, received little attention. The authors report the second case in the literature and the first without a history of antecedent trauma.

METHODS

The onset of the painful myelopathy in this patient was missed in the acute setting because of low suspicion. When the diagnosis was made, coadministered heparin had already been discontinued without reversal, and the patient's examination had already improved. Careful follow-up by neurologic examination and magnetic resonance imaging was obtained without spinal angiography being performed.

RESULTS

The patient regained his prehemorrhage neurologic status, experienced no further bleeding, and his coronary ischemia remained subclinical.

CONCLUSIONS

Spinal epidural hemorrhage secondary to thrombolytic therapy is becoming increasingly common. Urgent surgical decompression is generally warranted to preserve neurologic function. In cases where the deficit is minimal or resolving, a conservative approach may be warranted with magnetic resonance imaging but not angiographic follow-up.

Does antithrombotic therapy influence residual thrombus after thrombolysis of platelet-rich thrombus? Effects of recombinant hirudin, heparin, or aspirin

BACKGROUND

Thrombolysis to normal flow in patients with acute myocardial infarction preserves left ventricular function and decreases mortality. Failure of early reperfusion, reocclusion, or residual thrombus may be due to concurrent activation of the platelet-coagulation system. Thus, we hypothesized that the best concomitant antithrombotic therapy (recombinant [r]-hirudin, heparin, or aspirin) will maximally accelerate thrombolysis by r-tissue-type plasminogen activator (rTPA) and reduce residual thrombus.

METHODS AND RESULTS

Occlusive thrombi were formed in the carotid arteries of 29 pigs (by balloon dilatation followed by endarterectomy at the site of injury-induced vasospasm) and matured for 30 minutes before rTPA was started, with or without antithrombotic therapy. Thrombolysis was assessed with the use of angiography and measurement of residual thrombus. Pigs were allocated to one of five treatments: placebo, rTPA, rTPA plus r-hirudin, rTPA plus heparin, or rTPA plus intravenous aspirin. No placebo-treated pig reperfused. Two of six animals treated with rTPA alone reperfused compared with seven of seven animals treated with rTPA plus r-hirudin (reperfusion time, 33 +/- 10 minutes), six of seven animals treated with rTPA plus heparin (reperfusion time, 110 +/- 31 minutes), and two of six animals with rTPA plus aspirin. The activated partial thromboplastin time was prolonged in only the rTPA plus r-hirudin group (25 +/- 0.1 times baseline) and the rTPA plus heparin group (5.3 +/- 0.2 times baseline). Residual 111In-platelet and 125I-fibrin(ogen) depositions were lower in the heparin-treated group and lowest in the r-hirudin-treated group (heparin versus hirudin, respectively; incidence of residual macroscopic thrombus was six of six animals versus two of seven [P = .01]; 125I-fibrin(ogen), 170 +/- 76 versus 48 +/- 6 x 10(6) molecules/cm2 [P = .02]; 111In-platelets, 47 +/- 15 versus 13 +/- 2 x 10(6)/cm2, P = .10). No pigs developed spontaneous bleeding.

CONCLUSIONS

Thrombin inhibition with heparin or r-hirudin significantly accelerated thrombolysis of occlusive platelet-rich thrombosis, but only the best antithrombotic therapy (r-hirudin) eliminated or nearly eliminated residual thrombus.

Thrombolytic therapy. From myocardial to cerebral infarction. The MAST-I Group. Multicentre Acute Stroke Trial

Thrombolysis is proposed for the acute treatment of cerebral infarction as it is able to recanalize occluded arteries and thus potentially restore normal perfusion of the cerebral parenchyma, but the results concerning the efficacy of this treatment are still inconclusive. However, it has been fully demonstrated that thrombolytic treatment, leads to a significant reduction in mortality, in patients with acute myocardial infarction. Data from all of the pilot studies using SK or tPA treatment in acute stroke are described in this review, which underlines the incidence of hemorrhagic transformation (hemorrhagic infart and parenchymal hematoma) and its possible correlation to clinical worsening. Pharmacological, experimental and clinical studies encourage the carrying out of large-scale clinical trials using thrombolytics in patients with acute cerebral infarction. Significant data relating to ongoing controlled clinical trials will be available in the near future; only after the analysis of these results will it be possible to confirm the efficacy of thrombolytics in acute stroke.

Clinical and economic lessons from studies of coronary thrombolysis

The era of coronary reperfusion in acute coronary care was made possible by the recognition that acute myocardial infarction is usually due to a ruptured atherosclerotic plaque with associated thrombosis. If the infarct artery becomes occluded, a typical electrocardiographic picture is produced and a wave-front of myocardial necrosis ensues. Reperfusion during the early postinfarction hours can halt this process and preserve myocardial function. Pooled analysis of data in almost 60,000 patients has shown that thrombolysis saves lives relative to no reperfusion therapy. Streptokinase has been the standard thrombolytic agent, but recent data from the GUSTO trial show that tissue plasminogen activator (t-PA) given in an accelerated dosing regimen saves one extra patient per hundred treated. The mechanism of benefit of t-PA is improved early and complete restoration of blood flow down the infarct artery. Economic analysis of the GUSTO data shows that t-PA is an "economically attractive" therapeutic technology with a cost-effectiveness ratio of approximately $33,000 per life-year added relative to streptokinase therapy. Because of the growth of managed care and other cost-containment forces, expensive new medical technologies will increasingly need to demonstrate that they produce extra medical benefits in appropriate measure for their extra costs.

Comparison of "accelerated" tissue plasminogen activator with streptokinase for treatment of suspected myocardial infarction

PURPOSE

A computerized decision analysis, based on the results of published clinical trials, assessed the risks, benefits, and costs of different thrombolytic regimens for suspected myocardial infarction (MI) throughout the likely range of clinical circumstances.

DATA SOURCE

Medline search and articles' bibliographies.

STUDY SELECTION

All studies reporting efficacy and side effects of thrombolysis.

DATA ANALYSIS

Life-expectancy outcomes of thrombolytic therapies for possible MI modeled by decision analysis.

RESULTS

The analysis allows a clinician to estimate the benefits, risks, and relative costs of thrombolytic therapies throughout the likely range of individual clinical circumstances. When applied, for example, to the average patient in ISIS-2, estimated gains are 150 quality-adjusted days of life (QALDs) from treatment with streptokinase (SK) and 255 QALDs with "accelerated" tPA (tPA). tPA costs $1,686 more than SK, taking into account the cost of lifelong care of the extra strokes incurred. Nevertheless, the chances of stroke above which thrombolysis is not preferred are 5.0% for SK and 8.0% for tPA, with tPA remaining the preferred treatment for six hours after symptom onset; thereafter, SK is marginally preferred, but at much lower cost. Both regimens are beneficial in older patients provided the chances of MI and death are "average" or greater.

CONCLUSION

When the chances of MI and death are known, decision analysis can be a useful bedside tool to guide thrombolytic therapy and subsequently, if needed, to review and defend the treatment decisions made.

Influence of bypass grafting to the infarct artery on late potentials in coronary operations

BACKGROUND

Late potentials (LPs) after myocardial infarction identify the risk of arrhythmic events and sudden death, and the absence of anterograde flow in the infarct-causing occluded coronary artery frequently is associated with LPs on signal-averaged electrocardiography. The present study was designed to clarify the influence of revascularization of the infarct artery on the LPs in the late course after myocardial infarction.

METHODS

We studied 21 patients after myocardial infarction with positive LPs who had at least one occluded infarct coronary artery. We investigated the LPs on signal-averaged electrocardiograms on the day of elective coronary artery bypass grafting (CABG) and 1 week after CABG.

RESULTS

There were 25 infarct arteries in the study patients, 13 of which were grafted. The positive LPs disappeared soon after CABG in 13 patients, 10 of whom had grafts to all of the infarct arteries. The LPs persisted in 8, who received no graft to the infarct artery. One week after CABG, the LPs were still present in 4, all of whom had no graft to the infarct right coronary artery.

CONCLUSIONS

In patients with positive LPs late after myocardial infarction, grafting to the infarct artery eliminated the LPs soon after CABG.