Correspondence
Revascularization for Cardiogenic Shock
N Engl J Med 1999; 341:2095-2096December 30, 1999
- Article
To the Editor:
Hochman et al. (Aug. 26 issue)1 reported the results of a randomized clinical trial in which they compared early revascularization with medical management in patients who had cardiogenic shock after an acute myocardial infarction. They did not find a statistically significant difference in mortality between the groups at 30 days. Mortality at six months, however, was significantly lower in the revascularization group.
A survival advantage at 30 days would have implied salvage of ischemic myocardium by revascularization that led to early improvement in left ventricular pump function. In this study, the authors' failure to show improvement in survival at 30 days probably resulted from the relatively long time to revascularization (>12 hours on average), too long a time for salvage of ischemic myocytes.2 The improvement in survival at six months in the revascularization group may have been due to the salutatory effects of a patent infarct-related artery at the time of left ventricular remodeling. Clinical and laboratory studies have demonstrated that having a patent infarct-related artery has a beneficial effect on postinfarction left ventricular remodeling and the subsequent development of congestive heart failure.3,4
We wonder whether patients treated with delayed revascularization would have a result similar to those treated with revascularization on an emergency basis. The authors could shed light on this question by comparing the outcome in the patients in the medically treated group who underwent late revascularization (>54 hours after randomization) with that in patients who did not undergo revascularization. If our hypothesis is correct, the patients who underwent revascularization late should have had a survival benefit at six months that was similar to the benefit in patients treated on an emergency basis. This long-term benefit would be due to amelioration of the negative effects of postinfarction left ventricular remodeling on long-term ventricular function.
Given these considerations, a more appropriate interpretation of the data might be that all patients in shock after myocardial infarction should undergo revascularization of their infarct-related artery before discharge to prevent the negative effects of postinfarction left ventricular remodeling on long-term left ventricular function. Early emergency revascularization would be reserved for patients in whom patency of the infarct-related artery could be achieved very early (less than six hours) after the beginning of the infarction. Such a strategy would limit the number of interventions in moribund patients and provide the best long-term benefit to patients who could be treated.
4 ReferencesRobert C. Gorman, M.D.
Joseph H. Gorman, III, M.D.
Benjamin M. Jackson, M.S.
Hospital of the University of Pennsylvania, Philadelphia, PA 19104-42831
Hochman JS ,Sleeper LA ,Webb JG , et al. Early revascularization in acute myocardial infarction complicated by cardiogenic shock. N Engl J Med 1999;341:625-634
Full Text | Web of Science | Medline2
Jennings RB ,Steenbergen C Jr ,Reimer KA . Myocardial ischemia and reperfusion. Monogr Pathol 1995;37:47-80
Medline3
Hochman JS ,Choo H . Limitation of myocardial infarct expansion by reperfusion independent of myocardial salvage. Circulation 1987;75:299-306
CrossRef | Web of Science | Medline4
Hirayama A ,Adachi T ,Asada S , et al. Late reperfusion for acute myocardial infarction limits the dilatation of left ventricle without the reduction of infarct size. Circulation 1993;88:2565-2574
Web of Science | Medline
Author/Editor Response
The authors reply:
To the Editor: We agree that there may be benefits of early revascularization associated with myocardial salvage that are different from the potential for late revascularization to improve long-term ventricular remodeling and electrical stability. The distinction between early and late reperfusion is often blurred, particularly in the setting of cardiogenic shock. Salvage of myocardium can be achieved more than 12 hours after myocardial infarction because of ischemic preconditioning and intermittent opening and closing of the infarct-related artery. Furthermore, relief of the severe ischemia and progressive necrosis that result from the sustained coronary hypoperfusion that occurs in shock may allow myocardial salvage up to 24 to 48 hours after myocardial infarction. In addition, late revascularization for patients who have triple-vessel and left main disease with impaired left ventricular function should improve long-term survival. We agree that it is also possible that patency of the infarct-related artery after an apparently complete infarction may improve long-term outcome by multiple mechanisms.1,2 A randomized clinical trial testing this hypothesis is beginning.
The SHOCK (Should We Emergently Revascularize Occluded Coronaries for Cardiogenic Shock) study was not designed to distinguish between the benefits of early and late opening of infarct-related arteries. Our data can directly assess only the effect of a strategy of early revascularization, a median of 14 hours after myocardial infarction (interquartile range, 8 to 26 hours), as compared with no revascularization or late revascularization, at a median time of 119 hours (interquartile range, 95 to 181 hours). We did not demonstrate that there was no benefit associated with early revascularization at 30 days; rather, we failed to prove that there was a benefit. The distinction is important. Although the difference in survival rate was statistically significant only beginning at 6 months, the curves were separating by 30 days. We agree with the statement in Ryan's editorial (Aug. 26 issue)3 that the difference between the groups in survival at 30 days (although only a trend) was large, at 9.3 lives saved per 100 patients treated, in contrast to 2 lives saved per 100 patients treated with thrombolytic agents.4 For patients less than 75 years old the difference at 30 days was large (15.4 lives saved per 100 patients) and statistically significant.
The six-month mortality rate for patients assigned to medical therapy who survived long enough and were clinically selected to undergo late revascularization was relatively low, at 38 percent (14 of 37 patients), as expected. The superiority of early revascularization, however, is suggested by the similar 1-year survival rate among 30-day survivors in the medical-therapy group, whether or not they underwent delayed revascularization. Analyses are being performed to try to assess the effect of early as compared with late revascularization on longer-term survival, but any conclusions will be limited because patients in the initial medical-therapy group were not randomly assigned to late or no revascularization.
4 ReferencesJudith S. Hochman, M.D.
St. Luke's–Roosevelt Hospital Center, New York, NY 10025Harvey D. White, D.Sc.
Green Lane Hospital, Auckland 1030, New ZealandThierry H. LeJemtel, M.D.
Albert Einstein College of Medicine, Bronx, NY 104611
Hochman JS . Has the time come to seek and open all occluded infarct-related arteries after myocardial infarction? J Am Coll Cardiol 1996;28:846-848
CrossRef | Web of Science | Medline2
White HD ,Cross DB ,Elliott JM , et al. Long-term prognostic importance of patency of the infarct-related coronary artery after thrombolytic therapy for acute myocardial infarction. Circulation 1994;89:61-67
Web of Science | Medline3
Ryan TJ . Early revascularization in cardiogenic shock -- a positive view of a negative trial. N Engl J Med 1999;341:687-688
Full Text | Web of Science | Medline4
Fibrinolytic Therapy Trialists' (FTT) Collaborative Group
Web of Science | Medline
