Double-blind, randomized trial of an anti-CD18 antibody in conjunction with recombinant tissue plasminogen activator for acute myocardial infarction: limitation of myocardial infarction following thrombolysis in acute myocardial infarction (LIMIT AMI) study.

BACKGROUND: Inhibition of leukocyte adhesion can reduce myocardial infarct size in animals. This study was designed to define the safety and efficacy of a recombinant, humanized, monoclonal antibody to the CD18 subunit of the beta2 integrin adhesion receptors (rhuMAb CD18), in reducing infarct size in patients treated with a thrombolytic agent. METHODS AND RESULTS: The Limitation of Myocardial Infarction following Thrombolysis in Acute Myocardial Infarction Study (LIMIT AMI) was a randomized, double-blind, placebo-controlled, multicenter study conducted in 60 centers in the United States and Canada. A total of 394 subjects who presented within 12 hours of symptom onset with ECG findings (ST-segment elevation) consistent with AMI were treated with recombinant tissue plasminogen activator and were also given an intravenous bolus of 0.5 or 2.0 mg/kg rhuMAb CD18 or placebo. Coronary angiography was performed at 90 minutes, 12-lead ECGs were obtained at baseline, 90, and 180 minutes, and resting sestamibi scans were performed at >/=120 hours. Adjunctive angioplasty and use of glycoprotein IIb/IIIa antiplatelet agents at the time of angiography were discretionary. There were no treatment effects on coronary blood flow, infarct size, or the rate of ECG ST-segment elevation resolution, despite the expected induction of peripheral leukocytosis. A slight trend toward an increase in bacterial infections was observed with rhuMAb CD18 (P=0.33). CONCLUSIONS: RhuMAb CD18 was well tolerated but not effective in modifying cardiac end points.

Underutilization of reperfusion therapy in eligible African Americans with acute myocardial infarction: Role of presentation and evaluation characteristics.

BACKGROUND: Immediate reperfusion therapy to restore coronary blood flow is recommended for all eligible patients with acute myocardial infarction. However, reperfusion therapy is reportedly underutilized among African Americans, even when they are eligible. Reasons for the lack of use have not been fully explored. METHODS: We examined the demographic, clinical, and treatment data of 10,469 African Americans with acute myocardial infarction who were eligible for reperfusion therapy, enrolled in the National Registry of Myocardial Infarction-2 from June 1994 through March 1998. RESULTS: The mean age was 62.58 (+/-14.4) years, and 44.7% were female. Although eligible, 47% of the African Americans in this study did not receive reperfusion therapy. In a multivariate analysis, the absence of chest pain at presentation (odds ratio [OR] 0.31, 95% CI 0.26-0.37) and initial admission diagnoses other than definite myocardial infarction (OR for receipt of reperfusion <0.12) were the strongest predictors of lack of early reperfusion therapy. Progressive delays in hospital arrival and hospital evaluation predicted a lower likelihood of early reperfusion. Prior stroke (OR 0.63, 95% CI 0.50-0.78), myocardial infarction (OR 0.75, 95% CI 0.65-0.86), and congestive heart failure (OR 0.49, 95% CI 0.40-0.60) were all associated with lack of reperfusion therapy. CONCLUSION: Almost half of eligible African American patients with myocardial infarction did not receive reperfusion therapy. Potential reasons may include atypical presentation, patient and institutional delay, and underappreciation of myocardial infarction by care providers. Strategies to address these factors may improve the rate of use of reperfusion therapy.

Ninety-minute exclusion of acute myocardial infarction by use of quantitative point-of-care testing of myoglobin and troponin I.

BACKGROUND: Diagnostic strategies with ECG and serum cardiac markers have been used to rule out acute myocardial infarction in 6 to 12 hours. The present study evaluated whether a multimarker strategy that used point-of-care measurement of myoglobin, creatine kinase (CK)-MB, and troponin I could exclude acute myocardial infarction in

Pharmacologic conversion of atrial fibrillation: a systematic review of available evidence.

This report reviews the efficacy of currently available antiarrhythmic agents for conversion of atrial fibrilation (AF) to normal sinus rhythm (NSR). A systematic search of literature in the English language was done on computerized databases, such as MEDLINE, EMBASE, and Current Contents, in reference lists, by manual searching, and in contact with expert informants. Published studies involving humans that described the use of antiarrhythmic therapy for conversion of AF to NSR were considered and only studies that examined the use of agents currently available in the United States were included. Studies exclusively describing antiarrhythmic therapy for conversion of postsurgical AF were excluded. The methodology and results of each trial were assessed and attempts were made to acquire additional information from investigators when needed. Assessment of methodological quality was incorporated into a levels-of-evidence scheme. Eighty-eight trials were included, of which 34 (39%) included a placebo group (level I data). We found in recent-onset AF of less than 7 days, intravenous (i.v.) procainamide, high-dose i.v. or high-dose combination i.v. and oral amiodarone, oral quinidine, oral flecainide, oral propafenone, and high-dose oral amiodarone are more effective than placebo for converting AF to NSR. In recent-onset AF of less than 90 days, i.v. ibutilide is more effective than placebo and i.v. procainamide. In chronic AF, oral dofetilide converts AF to NSR within 72 hours, and oral propafenone and amiodarone are effective after 30 days of therapy. We conclude than for conversion of recent-onset AF of less than 7 days, procainamide may be considered a preferred i.v. agent and propafenone a preferred oral agent. For conversion of recent-onset AF of longer duration (less than 90 days), i.v. ibutilide may be considered a preferred agent. For patients with chronic AF and left ventricular dysfunction, direct current cardioversion is the preferred conversion method. Larger, well-designed randomized controlled trials with clinically important endpoints in specific populations of AF patients are needed.

Determinants of mortality after myocardial infarction in patients with advanced renal dysfunction.

Previous studies using administrative data have shown high mortality in patients with renal failure requiring dialysis after acute myocardial infarction (AMI). There has been little investigation into the mortality after AMI in those with advanced renal disease who are not on dialysis therapy. We analyzed a prospective coronary care unit registry of 1,724 patients with ST segment elevation myocardial infarction admitted over an 8-year period at a single tertiary-care center. Those not on chronic dialysis therapy were stratified into groups based on corrected creatinine clearance, with cutoff values of 46.2, 63.1, and 81.5 mL/min/72 kg. Dialysis patients (n = 47) were considered as a fifth comparison group. Older age, black race, diabetes, hypertension, previous coronary disease, and heart failure were incrementally more common across increasing renal dysfunction strata. There were also graded increases in the relative risk for atrial and ventricular arrhythmias, heart block, asystole, development of pulmonary congestion, acute mitral regurgitation, and cardiogenic shock. Primary angioplasty, thrombolysis, and beta-blockers were used less often across the risk strata (P < 0.0001 for all trends). There was an early mortality hazard (age-adjusted relative risk, 8.76; P < 0.0001) for those with renal dysfunction but not on dialysis therapy for the first 60 months, followed by graded decrements in survival across increasing renal dysfunction strata. The excess mortality in this population appears to be mediated through arrhythmias, adverse hemodynamic events, and the lower use of mortality-reducing therapy.

How safely and for how long can warfarin therapy be withheld in prosthetic heart valve patients hospitalized with a major hemorrhage?

STUDY OBJECTIVES: To identify the risk of thromboembolism after withholding or reversing the effect of warfarin therapy following a major hemorrhage. DESIGN: Retrospective medical record review. SETTING: Tertiary-care hospital. PATIENTS: Twenty-eight patients with prosthetic heart valves receiving warfarin were hospitalized for major hemorrhage from 1990 to 1997. The mean +/- SD age was 61 +/- 11 years (15 men and 13 women). Twenty patients had St. Jude valves, 4 patients had Carpentier-Edwards bioprosthetic valves, 2 patients had Starr Edwards valves, and 2 patients had Bjork-Shiley valves. Valves were in the mitral position in 12 patients, the aortic position in 12 patients, and both mitral and aortic positions in 4 patients. The average interval from valve surgery to index bleeding was 7 years. Twenty-five patients had GI or retroperitoneal hemorrhage, 2 patients had an intracranial hemorrhage, and 1 patient had a subdural hematoma. INTERVENTIONS: Vitamin K was administered to five patients and fresh frozen plasma was given to seven patients to reverse anticoagulation. The mean duration of anticoagulation withholding was 15 +/- 4 days. MEASUREMENTS AND RESULTS: None of the patients had thromboembolic complications. There were four in-hospital deaths. Twenty-two of the 24 hospital survivors resumed warfarin therapy at hospital discharge. At 6-month follow-up, 10 of 19 patients remaining on warfarin therapy had recurrent GI bleeding. CONCLUSIONS: Thromboembolic risk is low in prosthetic heart valve patients hospitalized with major hemorrhage when their warfarin therapy is reversed or withheld. Recurrent bleeding within 6 months of the resumption of anticoagulation is common, and aggressive treatment of the bleeding source and the risk-benefit ratio of continued anticoagulation need to be considered.

Risks associated with renal dysfunction in patients in the coronary care unit.

OBJECTIVES: The purpose of this study was to quantify the impact of baseline renal dysfunction on morbidity and mortality in patients in the coronary care unit (CCU). BACKGROUND: The presence of renal dysfunction is an established independent predictor of survival after acute myocardial infarction and revascularization procedures. METHODS: We analyzed a prospective CCU registry of 12,648 admissions by 9,557 patients over eight years at a single, tertiary center. Admission serum creatinine was available in 9,544 patients. Those not on long-term dialysis were classified into quartiles of corrected creatinine clearance, with cut-points of 46.2, 63.1 and 81.5 ml/min per 72 kg. Dialysis patients (n = 527) were considered as a fifth comparison group. RESULTS: Baseline characteristics, including older age, African-American race, diabetes, hypertension, previous coronary disease and heart failure, were incrementally more common across increasing renal dysfunction strata. There were graded increases in the relative risk for atrial and ventricular arrhythmias, heart block, asystole, development of pulmonary congestion, acute mitral regurgitation and cardiogenic shock across the risk strata. Survival analysis demonstrated an early mortality hazard for those with renal dysfunction, but not on dialysis, for the first 60 months, followed by graded decrements in survival across increasing renal dysfunction strata. CONCLUSIONS: Baseline renal function is a powerful predictor of short- and long-term events in the CCU population. There is an early hazard for in-hospital and postdischarge mortality for those with a corrected creatinine clearance <46.2 ml/min per kg, but not on dialysis.

Effect of delay on racial differences in thrombolysis for acute myocardial infarction.

OBJECTIVE: To analyze the effect of delay times on racial differences in thrombolysis for acute myocardial infarction. BACKGROUND: Lower rates of thrombolytic therapy in blacks with acute myocardial infarction have recently been reported, but the reasons for this disparity are unknown. We hypothesized that lower rates of thrombolysis are caused by delay in presentation after symptom onset. METHODS: From November 1992 through November 1996, consecutive patients with a first acute myocardial infarction presenting to a large, urban teaching hospital were prospectively enrolled. Delay times were determined retrospectively from review of medical records. Patients were prospectively followed up for in-hospital cardiac events and death. A multivariable regression model was built to relate presentation times and other variables to thrombolysis administration. RESULTS: A total of 395 patients were included in the study, of which 33% were black. Symptom onset to emergency department presentation and door-to-needle times were significantly longer in blacks. Thrombolysis was administered significantly less often in blacks compared with whites (47% vs 68%, P =.001). Black race and age above 60 years were independently associated with delayed presentation and prolonged door-to-needle times. Black race, time to presentation, and non-Q-wave myocardial infarction were independently associated with not receiving thrombolysis. In-hospital mortality rates were similar in both groups. CONCLUSIONS: Blacks presented later than whites for first acute myocardial infarction. Late arrival strongly influenced the rate of thrombolysis administration. Lower rates of thrombolysis and prolonged door-to-needle times were apparent in blacks after adjustment for delay times and other clinical factors, a finding that merits further investigation.

Electrocardiographic presentation of blacks with first myocardial infarction does not explain race differences in thrombolysis administration.

BACKGROUND: Previous studies have suggested that thrombolysis is used less often in blacks than in whites. However, whether the greater prevalence of contraindications or less specific electrocardiographic manifestations of myocardial infarction (MI) account for this difference is unclear. METHODS AND RESULTS: We studied 498 consecutive patients (32% blacks) with first MI. Initial electrocardiograms were analyzed, blinded to race and outcome, for ST-segment deviation and bundle branch block to determine eligibility for thrombolysis. The relation of electrocardiographic eligibility for thrombolysis and actual use of thrombolysis in both races was explored. Among blacks, 45% received thrombolysis compared with 66% of whites (P <.001). A similar proportion of blacks and whites were eligible for thrombolysis (59% and 66% respectively, P =. 116), but 62% of electrocardiography-eligible blacks were treated with thrombolysis compared with 75% of whites (P =.016). After accounting for eligibility for electrocardiography and other clinical variables likely to affect the decision to administer thrombolysis by means of conditional logistic regression, blacks were still less likely to receive thrombolysis (relative risk 0.73; 95% confidence interval 0.55 to 0.97). CONCLUSIONS: We conclude that the differences in thrombolysis administration to blacks and whites are not accounted for by differences in electrocardiographic presentation or other measured variables. Unmeasured differences in clinical presentation of MI may explain racial differences in thrombolysis and merits further study.

Myocarditis and pericarditis with tamponade associated with disseminated tuberculosis.

Tuberculous involvement of the myocardium is relatively rare. Tuberculous pericarditis with tamponade and myocarditis in a young woman with no evidence of immunosuppression and disseminated tuberculosis is described. Three distinct forms of myocardial involvement are recognized: nodular tubercles (tuberculomas) of the myocardium; miliary tubercles of the myocardium; and an uncommon diffuse infiltrative type. The myocardium is involved by a hematogenous route, by lymphatic spread or contiguously from the pericardium. The diagnosis can be made by endomyocardial biopsy if clinical suspicion is strong and echocardiographic findings are suggestive. Antituberculosis drugs may be curative. With an increasing prevalence of tuberculosis, the possibility of potentially lethal myocardial tuberculosis is important to consider.

Hemodynamic effects of a novel sodium channel activator in dogs with chronic heart failure.

The use of positive inotropic agents, such as sympathomimetics and phosphodiesterase inhibitors, in heart failure (HF) is limited by proarrhythmic and positive chronotropic effects. In the present study, we compared the hemodynamic effects of intravenous LY366634 (LY), a Na+ channel enhancer, with dobutamine (DOB), in eight dogs with HF produced by intracoronary microembolizations. We also determined whether intravenous LY has synergistic effects when combined with digoxin. After baseline measurements, infusion of DOB was initiated at a dose of 2 micrograms/kg/min and increased until an increase of heart rate (HR) 30% of baseline or ventricular arrhythmias developed. Once hemodynamics returned to baseline, LY was infused at a dose of 2 micrograms/kg/min and increased until the LV fractional area of shortening (FAS), determined echocardiographically, reached a similar level as with DOB. Both drugs increased FAS equivalently compared to baseline (DOB, 24 +/- 3 to 47 +/- 2; LY, 27 +/- 2 to 46 +/- 2%). DOB increased HR from 78 +/- 4 min-1 at baseline to 107 +/- 7 min-1 at maximal dose (p < 0.05) and provoked serious arrhythmias in one dog. In contrast, LY infusion did not increase HR (82 +/- 7 vs. 80 +/- 8 min-1) or elicit arrhythmias. After 1 week of oral digoxin, dogs were infused again with LY. A lower dose of LY was needed to achieve the same increase in FAS compared to LY alone, but this was not statistically significant. The combination of LY with digoxin did not increase HR or evoke arrhythmias. We conclude that in dogs with HF, intravenous LY improves LV function to the same extent as DOB without increasing HR or evoking ventricular arrhythmias. The combination of LY with digoxin elicits a safe positive inotropic response.

Treatment of postoperative atrial fibrillation.

Postoperative atrial fibrillation can occur in approximately 30% of patients. Although often a benign complication, it can result in significant morbidity and prolong hospitalization with attendant increased expenditure of health care resources. A rigid approach for prophylaxis and treatment is illogical, but with separate focus on rate control and cardioversion, a sinus mechanism can be safely and reliably achieved with minimal patient discomfort.

Low-molecular-weight heparins in the management of acute coronary syndromes.

Acute coronary syndromes (unstable angina and non-Q-wave myocardial infarction) are caused by the rupture of an atherosclerotic plaque, platelet activation, and fibrin deposition resulting in thrombosis. Aspirin and unfractionated heparin have traditionally been the treatments of choice for patients with acute coronary syndromes. Low-molecular-weight heparins offer potential advantages over unfractionated heparin, having proven equally effective for the treatment and prevention of many thromboembolic processes. Recently, a number of randomized controlled trials have been conducted to evaluate the role of low-molecular-weight heparins in the management of patients with unstable angina or non-Q-wave myocardial infarction. The purpose of this article is to review and evaluate the available literature on the use of low-molecular-weight heparins in the management of acute coronary syndromes to establish their role in therapy.

A randomized, multicenter trial of weight-adjusted intravenous heparin dose titration and point-of-care coagulation monitoring in hospitalized patients with active thromboembolic disease. Antithrombotic Therapy Consortium Investigators.

BACKGROUND: Therapy with intravenous unfractionated heparin improves clinical outcome in patients with active thromboembolic disease, but achieving and maintaining a therapeutic level of anticoagulation remains a major challenge for clinicians. METHODS: A total of 113 patients requiring heparin for at least 48 hours were randomly assigned at 7 medical centers to either weight-adjusted or non-weight-adjusted dose titration. They were separately assigned to either laboratory-based or point-of-care (bedside) coagulation monitoring. RESULTS: Weight-adjusted heparin dosing yielded a higher mean activated partial thromboplastin time (aPTT) value 6 hours after treatment initiation than non-weight-adjusted dosing (99.9 vs 78.8 seconds; P =.002) and reduced the time required to exceed a minimum threshold (aPTT >45 seconds) of anticoagulation (10.5 vs 8.6 hours; P =.002). Point-of-care coagulation monitoring significantly reduced the time from blood sample acquisition to a heparin infusion adjustment (0.4 vs 1.6 hours; P <.0001) and to reach the therapeutic aPTT range (51 to 80 seconds) (16.1 vs 19.4 hours; P =.24) compared with laboratory monitoring. Although a majority of patients participating in the study surpassed the minimum threshold of anticoagulation within the first 12 hours and reached the target aPTT within 24 hours, maintaining the aPTT within the therapeutic range was relatively uncommon (on average 30% of the overall study period) and did not differ between treatment or monitoring strategies. CONCLUSIONS: Weight-adjusted heparin dosing according to a standardized titration nomogram combined with point-of-care coagulation monitoring using the BMC Coaguchek Plus System represents an effective and widely generalizable strategy for managing patients with thromboembolic disease that fosters the rapid achievement of a desired range of anticoagulation. Additional work is needed, however, to improve on existing patient-specific strategies that can more effectively sustain a therapeutic state of anticoagulation.

Lower thrombolytic use for African Americans with myocardial infarction: an influence of clinical presentation?

BACKGROUND: After myocardial infarction, African Americans have been reported to undergo fewer catheterization and revascularization procedures than whites, but few studies have addressed racial variations in the delivery of thrombolytic therapy. METHODS: We conducted a retrospective analysis of data prospectively collected on consecutive patients admitted with acute myocardial infarction to the 16-bed coronary care unit of a large, urban teaching hospital. RESULTS: Over a 5-year period, 1948 consecutive patients were admitted with acute myocardial infarction to a single coronary care unit. Thrombolysis was administered to 19% of 1024 African Americans and 29% of 924 whites (P <.01). The initial diagnostic impression on admission was "definite" infarction less often in African Americans (30%) than in whites (43%, P <.001), a difference that appeared to largely account for the difference in thrombolytic administration in a multivariable model. Mortality adjusted for age and concomitant illnesses was similar in African Americans compared with whites (relative risk 1.0, 95% confidence interval 0.78 to 1.51). CONCLUSIONS: Much of the racial variation in thrombolytic administration could be accounted for by differences in clinical presentation, an issue that requires further study.

Combination therapy with tirofiban and enoxaparin in acute coronary syndromes.

BACKGROUND: Tirofiban, an intravenous glycoprotein IIb/IIIa antagonist, and enoxaparin, a low molecular weight heparin, have each been shown to be effective at reducing cardiac ischemic events compared to unfractionated heparin alone in separate trials of patients with unstable angina and non-Q-wave myocardial infarction. The combination of these agents may offer further therapeutic benefit. MATERIALS AND METHODS: Fifty-five patients with non-Q-wave myocardial infarction were randomized to receive double-blind treatment with tirofiban (0.1 microgram/kg/min i.v.) for 48-108 h coadministered with either enoxaparin (1 mg/kg sc q 12 h) (n=26) or unfractionated heparin (i.v. adjusted to activated partial-thromboplastin time) (n=27) to evaluate pharmacokinetics, pharmacodynamics, and safety. The primary objective of the study was to investigate the effect of unfractionated heparin versus enoxaparin on the plasma clearance of tirofiban. RESULTS: Coadministration of tirofiban and enoxaparin was generally well tolerated. Plasma clearance of tirofiban was 176.7+/-59.8 and 187.5+/-81.8 ml/min, respectively, for enoxaparin and unfractionated heparin-treated patients (P=NS). The mean difference was well within the prespecified criterion for comparability. Administration of tirofiban with enoxaparin vs. unfractionated heparin resulted in lesser variability and a trend towards greater inhibition of platelet aggregation using 5 microM adenosine phosphate agonist. More patients achieved target inhibition of platelet aggregation >70% in the tirofiban and enoxaparin group (84% vs. 65%, P=0.19). Median bleeding time was 21 min for tirofiban and enoxaparin vs. > or =30 min for tirofiban and unfractionated heparin (P=NS). For a given level of inhibition of platelet aggregation, bleeding time was less prolonged with tirofiban and enoxaparin than tirofiban and unfractionated heparin (adjusted mean bleeding time 19.6 vs. 24.9 min, P=0.02). Tirofiban plasma concentration and clearance were comparable whether coadministered with enoxaparin or unfractionated heparin. There were no major or minor bleeding events in either group by the TIMI criteria. INTERPRETATION: The more consistent inhibition of platelet aggregation and lower adjusted bleeding time of tirofiban and enoxaparin vs. tirofiban and unfractionated heparin support the therapeutic potential of combining these two agents. These data from the first clinical report of coadministration of a glycoprotein IIb/IIIa receptor antagonist and a low molecular weight heparin are consistent with prior data which show differential pharmacodynamic effects of enoxaparin and unfractionated heparin on platelet aggregation.