Use of Antiplatelet Agents and Anticoagulants in Post-Myocardial Infarction

Department of Veterans Affairs Cooperative Studies Program Clinical Trial comparing combined warfarin and aspirin with aspirin alone in survivors of acute myocardial infarction: primary results of the CHAMP study

BACKGROUND

Both aspirin and warfarin when used alone are effective in the secondary prevention of vascular events and death after acute myocardial infarction. We tested the hypothesis that aspirin and warfarin therapy, when combined, would be more effective than aspirin monotherapy. Methods and Results- We conducted a randomized open-label study to compare the efficacy of warfarin (target international normalized ratio 1.5 to 2.5 IU) plus aspirin (81 mg daily) with the efficacy of aspirin monotherapy (162 mg daily) in reducing the total mortality in 5059 patients enrolled within 14 days of infarction and followed for a median of 2.7 years. Secondary end points included recurrent myocardial infarction, stroke, and major hemorrhage. Four hundred thirty-eight (17.3%) of 2537 patients assigned to the aspirin group and 444 (17.6%) of 2522 patients assigned to the combination group died (log-rank P=0.76). Recurrent myocardial infarction occurred in 333 patients (13.1%) taking aspirin and in 336 patients (13.3%) taking combination therapy (log-rank P=0.78). Stroke occurred in 89 patients (3.5%) taking aspirin and in 79 patients (3.1%) taking combination therapy (log-rank P=0.52). Major bleeding occurred more frequently in the combination therapy group than in the aspirin group (1.28 versus 0.72 events per 100 person years of follow-up, respectively; P<0.001). There were 14 individuals with intracranial bleeds in both the aspirin and combination therapy groups.

CONCLUSIONS

In post-myocardial infarction patients, warfarin therapy (at a mean international normalized ratio of 1.8) combined with low-dose aspirin did not provide a clinical benefit beyond that achievable with aspirin monotherapy.

Clinical scoring systems for determining the prognosis of gastrointestinal bleeding

The prognosis of GI bleeding depends upon many factors. Patients should be evaluated carefully for risk factors. To avoid complications from GI bleeding, triage should be performed promptly after patient presentation. The history and physical examination should emphasize analysis of risk factors for severe GI bleeding and mortality. Factors that increase the morbidity and mortality include: age greater than 60 years; underlying comorbidity such as pulmonary diseases, liver diseases, renal diseases, encephalopathy, or cancer; physiologic stress from major surgery, trauma, or sepsis; coexisting disease in three organ systems; low hematocrit; melena or hematochezia; and prolonged prothrombin time. Hospitalized patients who require more than five units of packed erythrocytes transfusion or who develop hypotension or hypovolemic shock are more likely to need surgery. Patients with a high APACHE II score, the presence of esophageal varices, active bleeding, or other endoscopic stigmata of recent hemorrhage are more likely to rebleed and undergo surgery. The proliferation of multivariable prognostic scales, as described herein, provides ample evidence that the goal of developing a single comprehensive multivariable scale to accurately assess severity of disease and to determine prognosis of GI bleeding is still not achieved. Yet significant progress has occurred in this field, leading to the hope of developing a universally applicable multivariable scale.

Acute gastrointestinal bleeding in the intensive care unit. The intensivist's perspective

Gastrointestinal (GI) hemorrhage is a common and potentially lethal medical emergency that is a common cause for intensive care unit admission. The intensivist plays an important role as a member of the medical team managing the patient with GI bleeding who is at high risk because of severe bleeding, comorbidity, or the presence of endoscopic stigmata of recent hemorrhage. This article presents the intensivist's approach to GI hemorrhage in initial patient assessment, triage, resuscitation, specialist consultation, diagnostic evaluation, and medical therapy. This article focuses on types of GI bleeding of particular concern to the intensivist, including esophageal variceal bleeding, stress-related GI bleeding, and GI bleeding associated with myocardial infarcation.

Safety and efficacy of esophagogastroduodenoscopy after myocardial infarction

PURPOSE

To analyze the risks versus benefits of esophagogastroduodenoscopy performed soon after myocardial infarction.

PATIENTS AND METHODS

We studied 200 patients who underwent endoscopy within 30 days after myocardial infarction with 200 controls matched for age, sex, and endoscopic indication who underwent endoscopy without a history of myocardial infarction within the prior 6 months. Odds ratios (OR) and 95% confidence intervals (CI) are reported.

RESULTS

The indications for endoscopy included hematemesis in 88, melena in 43, fecal occult blood and anemia in 33, red blood per rectum in 13, abdominal pain in 13, and other indications in 10. Endoscopy was performed a mean (+/- SD) of 9.1 +/- 8.9 days after myocardial infarction, was diagnostic in 85% of all the patients, and was more frequently diagnostic when performed for hematemesis or melena than when performed for other indications (92% vs 71%, P <0.0003). Common diagnoses included duodenal ulcer, gastric ulcer, gastritis, and esophagitis. Fifteen post-myocardial infarction patients (7.5%) suffered endoscopic complications, including fatal ventricular tachycardia (n = 1), near respiratory arrest (n = 1), mild hypotension (n = 11), and moderate hypoxemia (n = 2), compared with three patients (1.5%) in the control group (OR = 5.3, CI = 1.5 to 19). Patients who had endoscopic complications after myocardial infarction had a significantly higher APACHE II score than those who did not (mean score of 17.3 +/- 5.8 vs 11.7 +/- 5.7, P <0.001). Endoscopic complications occurred in 21% (12 of 58) of post-myocardial infarction patients who were very ill (APACHE II score > or = 16) but in only 2% (3 of 142) of those whose condition was relatively stable (APACHE II score < or = 15, OR = 12; CI = 3.3 to 45). Hypotension before endoscopy and a high APACHE II score were independent risk factors for complications in post-myocardial infarction patients.

CONCLUSIONS

Relatively stable patients with upper gastrointestinal bleeding and recent myocardial infarction can and should undergo esophagogastroduodenoscopy. Most endoscopic complications in these patients are cardiopulmonary, and they generally occur in very ill patients.