RESUMEN
BACKGROUND: After an acute myocardial infarction, it is important to determine the risk of a subsequent coronary event. We studied the prognostic value of myocardial ischemia detected by ambulatory electrocardiographic (ECG) monitoring in patients who had recently had an acute myocardial infarction. METHODS: Five to seven days after acute myocardial infarction, 406 patients underwent 48-hour ambulatory ECG monitoring, with submaximal exercise testing before discharge and measurement of the left ventricular ejection fraction within 28 days after infarction. Death, nonfatal myocardial infarction, and admission to the hospital because of unstable angina were the principal end points recorded during the one-year follow-up period. RESULTS: The overall incidence of myocardial ischemia detected by ambulatory ECG monitoring was 23.4 percent. The mortality rates at one year were 11.6 percent among the patients with ischemia and 3.9 percent among those without ischemia (P = 0.009); 3.9 percent among the patients with a positive exercise test, 3.0 percent among those with a negative exercise test, and 16.4 percent among those in whom an exercise test was not performed (P < 0.001); and 3.6 percent among the patients with an ejection fraction greater than 50 percent, 3.5 percent among those with an ejection fraction between 35 and 50 percent, and 18.2 percent among those with an ejection fraction below 35 percent (P = 0.001). Using multiple logistic regression, we found that no diagnostic test performed after myocardial infarction provided additional prognostic information beyond that provided by the standard clinical variables used to predict the risk of death. When nonfatal myocardial infarction and admission to the hospital because of unstable angina were also included as outcome variables, ambulatory monitoring for ischemia was the only test that contributed significantly to the model. For the patients with ischemia detected by ambulatory monitoring, as compared with those who did not have evidence of ischemia, the odds ratio was 2.3 (95 percent confidence interval, 1.2 to 4.5) for death or nonfatal myocardial infarction (P = 0.009) and 2.8 (95 percent confidence interval, 1.6 to 4.8) for death, nonfatal myocardial infarction, or admission to the hospital because of unstable angina (P < 0.001). CONCLUSIONS: Myocardial ischemia detected by ambulatory ECG monitoring is common early after acute myocardial infarction and provides prognostic information beyond that available from standard clinical information.
Asunto(s)
Electrocardiografía Ambulatoria , Infarto del Miocardio/complicaciones , Isquemia Miocárdica/diagnóstico , Anciano , Angina Inestable/etiología , Prueba de Esfuerzo , Femenino , Humanos , Incidencia , Modelos Logísticos , Masculino , Persona de Mediana Edad , Infarto del Miocardio/mortalidad , Infarto del Miocardio/fisiopatología , Isquemia Miocárdica/epidemiología , Isquemia Miocárdica/etiología , Pronóstico , Recurrencia , Volumen SistólicoRESUMEN
We performed a double-blind randomized trial comparing high doses of subcutaneous heparin (12,500 units every 12 hours) with low doses (5000 units every 12 hours) for 10 days in the prevention of left ventricular mural thrombosis in 221 patients with acute anterior myocardial infarction. Left ventricular mural thrombosis was observed by two-dimensional echocardiography on the 10th day after infarction in 10 of 95 patients (11 percent) in the high-dose group and in 28 of 88 patients (32 percent) in the low-dose group (P = 0.0004). One patient in the high-dose group and four in the low-dose group had nonhemorrhagic strokes (P = 0.17). One patient in the low-dose group had a fatal pulmonary embolism. There was no difference in the frequency of hemorrhagic complications, which occurred in six patients in the high-dose group and four in the low-dose group. The mean (+/- SEM) plasma heparin concentration was 0.18 +/- 0.017 U per milliliter in the high-dose group and 0.01 +/- 0.005 U per milliliter in the low-dose group (P less than 0.0001). In the high-dose group, the mean plasma heparin concentration was 0.10 +/- 0.029 U per milliliter among patients with abnormal two-dimensional echocardiograms, as compared with 0.19 +/- 0.019 U per milliliter among patients with normal echocardiograms (P = 0.01). We conclude that heparin administered subcutaneously in a dosage of 12,500 units every 12 hours to patients with acute anterior transmural myocardial infarction is more effective than a lower dosage (5000 units every 12 hours) in preventing left ventricular mural thrombosis.
Asunto(s)
Enfermedad Coronaria/prevención & control , Trombosis Coronaria/prevención & control , Heparina/administración & dosificación , Infarto del Miocardio/complicaciones , Anciano , Ensayos Clínicos como Asunto , Trombosis Coronaria/diagnóstico , Método Doble Ciego , Ecocardiografía , Femenino , Estudios de Seguimiento , Hemorragia/inducido químicamente , Heparina/sangre , Heparina/uso terapéutico , Humanos , Inyecciones Subcutáneas , Masculino , Tiempo de Tromboplastina Parcial , Distribución AleatoriaRESUMEN
A case is presented, believed to be the first reported, describing recurrent myocardial infarction in an athletic 25-year-old man due to coronary arterial spasm, which was demonstrated at autopsy. A previous angiogram performed during life, after the first myocardial infarction, showed normal coronary arteries. The findings in this case are discussed with a review of the current knowledge pertaining to coronary arterial spasm.
Asunto(s)
Vasos Coronarios/fisiopatología , Infarto del Miocardio/etiología , Espasmo/complicaciones , Adulto , Aspartato Aminotransferasas/sangre , Autopsia , Angiografía Coronaria , Vasos Coronarios/patología , Electrocardiografía , Humanos , Masculino , Miocardio/patología , RecurrenciaRESUMEN
A CO2 rebreathing method for the measurement of cardiac output was evaluated by comparison with the direct Fick O2 method in 26 studies performed in 18 patients who were critically ill. The method requires measurement of CO2 output by collection of expired gas, of arterial PCO2, and of mixed venous PCO2 by rebreathing. Twenty-five comparisons were within +/- 20% of the direct Fick measurements, at cardiac outputs varying between 1.4 and 6.4 L/min. Knowledge of the cardiac output increased the quality of the interpretation of arterial blood PO2 measurements in the assessment of pulmonary gas exchange disturbances.