Emergency revascularization for acute myocardial infarction: an unproved experimental approach

True emergency coronary artery bypass surgery

Previous reports of emergency coronary artery bypass grafting often included cases that were not true surgical emergencies, thereby creating inappropriately favorable results. To accurately investigate this important subgroup of patients, we analyzed our recent experience with truly emergent coronary artery bypass grafting. From January 1984 to January 1989, 117 patients underwent true emergency bypass grafting for acute refractory coronary artery ischemia. Clinical deterioration was associated with failure of percutaneous angioplasty in 37 patients and instability during diagnostic catheterization in 13 patients. Refractory ischemia developed in the remaining patients while on the ward or in the intensive care unit. All operations were performed within four hours of surgical consultation, most within one hour. Overall in-hospital operative mortality was 14.5% (17/117), and 76.5% of deaths (13/17) were due to cardiac-related causes. Major morbidity occurred in 35.9% (42/117). Univariate analysis isolated ejection fraction, extent of coronary artery disease, previous myocardial infarction, hypertension, need for inotropic support, use of an intraaortic balloon pump, and cardiopulmonary resuscitation as risk factors for operative mortality. Stepwise multivariate analysis confirmed that previous myocardial infarction, hypertension, cardiopulmonary resuscitation, and reoperation were independently significant risk factors. Age, sex, diabetes, left main disease, and peripheral vascular disease had no significant impact on the prognosis. The 4% operative mortality (2/50) for patients taken directly to the operating room from the catheterization suite was significantly lower than the 22.4% mortality (15/67) associated with emergencies arising on the ward or intensive care unit (p less than 0.01). A logistic risk equation developed from this population accurately modeled operative mortality.(ABSTRACT TRUNCATED AT 250 WORDS)

Medical and surgical management of early Q wave myocardial infarction. I. Effects of surgical reperfusion on survival, recurrent myocardial infarction, sudden death and functional class at 10 or more years of follow-up

To define the outcome of patients given medical or surgical therapy for Q wave myocardial infarction, 387 patients were followed up for 10 to 13 years (mean 11.4). On study entry the groups had similar distributions for variables such as mean age, gender, previous myocardial infarction, abnormal creatine kinase activity, area of infarction, number of vessels diseased and clinical classification. The hospital mortality rate of the medical versus surgical group was 11.5% (23 of 200) versus 5.8% (11 of 187) (p = 0.07). Early reperfusion (that is, less than or equal to 6 h) resulted in a lower mortality rate than did medical therapy--2% (2 of 100) versus 11.5% (23 of 200) (p less than 0.05)--whereas the hospital mortality rate with late reperfusion was 10.3% (9 of 87). The long-term mortality rate of the medical and surgical groups was 41% (82 of 200) versus 27% (51 of 187) (p = 0.0007) with use of an adjusted Cox proportional hazards model. In the survivors, the differences between medical and surgical groups in recurrent myocardial infarction, mortality associated with reinfarction and sudden death were prospectively followed and evaluated by the life table method. Recurrent myocardial infarction was not prevented by surgical reperfusion or medical therapy (23% in both groups), however, the mortality rate in patients with recurrent infarction was higher in the medical therapy group--36.6% (15 of 41) versus 17.5% (7 of 40) (p = 0.04). The mortality difference did not depend on early or late surgical reperfusion. In the in-hospital survivors, the incidence of sudden death was 17.5% in the medical (31 of 177) versus 7.4% (13 of 176) in the surgical group (p = 0.01). This difference was much more pronounced in the early reperfusion group. Functional class was significantly lower than that for medical therapy in the early reperfusion but not the late reperfusion group. Thus, in comparable groups given medical and surgical therapy for acute myocardial infarction and followed up for greater than or equal to 10 years, surgical reperfusion appears to offer improved longevity in selected cases (when implemented early) but does not prevent recurrent myocardial infarction. The associated mortality with recurrent myocardial infarction is less as is the incidence of sudden death. Finally, lower functional class occurs most often in patients given early reperfusion.

Current practice patterns in the management of acute myocardial infarction. Survey of the American College of Chest Physicians

Over the past decade, the management of patients with acute myocardial infarction has undergone remarkable change due in part to the availability of new diagnostic and therapeutic modalities. Many of these techniques have gained widespread acceptance and use without the benefit of studies demonstrating efficacy. A survey of 391 members of the Section on Clinical Cardiology of the American College of Chest Physicians was conducted to assess current practice patterns in the management of acute myocardial infarction. Significant differences in the routine (greater than or equal to 50 percent of the time) use of various management approaches were found, with exercise tolerance testing, echocardiography, Holter monitoring, and cardiac rehabilitation frequently employed, whereas electrophysiologic studies, pyrophosphate scans, pulmonary artery catheterization, and cardiac pacing were infrequently used. Significant differences in the use of these procedures were noted with regard to the age of the physician and his or her geographic location of practice. These differences in practice patterns indicate that physicians have not reached consensus with regard to the value of these new diagnostic procedures and therapeutic approaches in the treatment of patients with acute myocardial infarction. Given the incremental costs of these procedures, clinical trials to assess their efficacy are clearly indicated.

Prevention of ischemic injury and early reperfusion derangements by hypothermic retroperfusion

Hypothermic synchronized retroperfusion was applied during coronary artery occlusion to determine its ability to alleviate junctional derangements of reperfusion and to reduce infarct size. The proximal left anterior descending coronary artery was occluded in 25 closed chest dogs for 3 hours and then reperfused for 7 days. Thirteen dogs with no reperfusion pretreatment served as a control group (Group A). In 12 dogs, hypothermic retroperfusion was applied from 30 minutes up to 3 hours of the occlusion period (Group B). Sequential two-dimensional echocardiographic and hemodynamic as well as metabolic measurements were performed. Compared with untreated control dogs, dogs with hypothermic synchronized retroperfusion had significantly reduced heart rate and rate-pressure product, decreased left ventricular volumes and improved ejection fraction during the occlusion period. Two-dimensional echocardiographically-derived ischemic zone systolic fractional area change and systolic wall thickening indicated significantly improved function as a result of retroperfusion. During the reperfusion period, untreated control dogs (group A) had more severe derangements in hemodynamics and wall motion than dogs treated by hypothermic retroperfusion (group B). Mortality was 30.7% in group A, 16.7% in group B and 7th day infarct size as percent of the left ventricle was 12.0 +/- 6.5 (mean +/- standard deviation) and 4.2 +/- 5.9, respectively (p less than 0.02). It is concluded that hypothermic synchronized retroperfusion applied after coronary occlusion and before reperfusion significantly improves cardiac function during occlusion, minimizes complications of reperfusion and reduces the ultimate infarct size. Because this form of circulatory assistance helps maintain cardiac function and delays the evolution of myocardial necrosis, its application may be beneficial during an evolving acute myocardial infarction before achievement of surgical or nonsurgical reperfusion.

Delayed operative intervention in cardiogenic shock after myocardial infarction

In a four-year period, 45 patients underwent counterpulsation for cardiogenic shock following myocardial infarction. Of these patients, 27 underwent angiography. Fifteen of them were not considered to be operative candidates because angiography demonstrated only single-vessel disease or diffuse distal coronary artery disease. Twelve patients were candidates for operation and were divided into three subgroups depending on the time of surgical intervention. One patient (Group 1) deteriorated while on counterpulsation, and underwent urgent angiography and operative intervention within 24 hours of balloon insertion. He is now in New York Heart Association (NYHA) Functional Class I. Group 2 consisted of 7 patients whose condition stabilized with use of the balloon but who could not be weaned. All underwent angiography from 7 to 14 days after insertion of the balloon. One patient died suddenly prior to operation. Six patients underwent coronary bypass from 8 to 21 days after balloon insertion. Five survived and are in NYHA Class II or III. Four patients were able to be weaned after angiography (Group 3). All had triple-vessel disease. Operation was undertaken six to eight weeks after infarction to treat persistent congestive heart failure or angina, or to improve chances of long-term survival. Two patients in this group survived. Our experience demonstrates that delayed intervention is an acceptable alternative to urgent operation.

Coronary revascularization surgery: feasibility after myocardial infarction

Since coronary revascularization improves prognosis in some patients with multivessel disease, can the potential benefits be extended to "prophylaxis" in selected postinfarction patients as well? These investigators sought the answer on the basis of patient characteristics, types of surgery, survival data, and mode of death in the postinfarction population of 129 patients who had early angiography.

Salvage of acutely ischemic myocardium by emergency coronary artery bypass grafting

After cardiac catheterization a 53-year old patient developed widespread myocardial ischemia that produced electromechanical dissociation and cardiogenic shock. The administration of methylprednisolone, the initiation of cardiopulmonary bypass and hypothermia within 40 min of the onset of ischemia, and reperfusion within 90 min of the onset of ischemia were sufficient to salvage a major portion of the ischemic myocardium.