Clinical Briefs
Treatment of Cardiogenic Shock
Source: Holmes DR, et al. Lancet 1997;349:75-78.
Gusto i was an international trial of combinations of streptokinase, heparin, and accelerated tissue plasminogen activator in patients with acute myocardial infarction. Other interventions were at the discretion of the treating physicians but were analyzed.Among patients with cardiogenic shock, 1891 were treated in the United States and 1081 treated in other countries. Adjusted 30-day mortality was significantly lower among patients treated in the United States than among those treated elsewhere (50% vs 66%; P < 0.001). This difference in mortality persisted for one year resulting in a risk ratio of 0.69 (95% CI 0.63-0.75; P < 0.001) for being treated in the United States.
Significant differences between the patients treated in the United States compared to the international patients included younger age (68 vs 70 years), a smaller proportion of anterior infarction (49% vs 53%), and a shorter time to thrombolytic therapy (3.1 vs 3.3 hours). However, it is unlikely that these small differences explain the large difference in mortality.
More revealing are the figures concerning aggressive diagnostic and therapeutic procedures. Cardiac catheterization was much more common in the United States (58% vs 23%) as was intra-aortic balloon pumping (35% vs 7%), right heart catheterization (57% vs 22%), and ventilatory support (54% vs 38%). Also, 483 (26%) of the patients treated in the United States underwent angioplasty compared with 82 (8%) patients in other countries.
In general, patients who underwent revascularization had a better survival in all countries. Thus, the authors conclude that the large difference in mortality of patients with cardiogenic shock following myocardial infarction between the United States and other countries was due to the greater use of invasive diagnostic and therapeutic interventions in the United States.
Although this study suggests that an aggressive approach to the management of cardiogenic shock is beneficial, the investigators cannot prove that the results were not due to a selection bias of the more viable patients toward these aggressive therapies, since the use of these resources was not mandated in the GUSTO protocol. Also, there were many patients who died early in cardiogenic shock before any aggressive procedures could be done, and the statistical model may not have fully compensated for these early deaths. Finally, the authors could not exclude that patients in the United States may be monitored more closely and cardiogenic shock treated earlier than in other countries. Despite these limitations, the study strongly suggests that an aggressive approach in selected patients with cardiogenic shock is highly beneficial.—mhc
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