Original Articles
Acute myocardial infarction complicated by systemic hypoperfusion without hypotension: report of the SHOCK trial registry

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Abstract

background: Cardiogenic shock is usually characterized by inadequate cardiac output and sustained hypotension. However, following a large myocardial infarction, peripheral hypoperfusion can occur with relatively well maintained systolic blood pressure, a condition known as nonhypotensive cardiogenic shock. The aim of this study was to determine the characteristics of patients with this condition.

methods: The SHOCK trial registry prospectively enrolled patients with suspected cardiogenic shock complicating acute myocardial infarction. We identified a group of 49 patients who presented with nonhypotensive shock, defined as clinical evidence of peripheral hypoperfusion with a systolic blood pressure >90 mm Hg without vasopressor circulatory support. Clinical characteristics, hemodynamic data, and outcomes in these patients were compared with a group of 943 patients with classic cardiogenic shock with hypotension. The age, gender, and distributions of coronary risk factors were similar in both groups.

results: Patients with nonhypotensive shock were more likely to have an anterior wall myocardial infarction (71% versus 53%, P = 0.03). Both groups of patients had similar rates of treatment with thrombolytic therapy, angioplasty, and bypass surgery. Patients with nonhypotensive shock had an in-hospital mortality rate of 43% as compared with a rate of 66% among patients who had classic cardiogenic shock with hypotension (P = 0.001). Mortality among 76 patients who presented with a systolic blood pressure <90 mm Hg but no hypoperfusion was 26%.

conclusions: Even in the presence of normal blood pressure, clinical signs of peripheral hypoperfusion, which may be subtle, are associated with a substantial risk of in-hospital death following acute myocardial infarction.

Section snippets

Methods

The SHOCK study was a prospective 30-site registry and randomized trial in patients with cardiogenic shock after acute myocardial infarction. Patients who did not meet the stringent enrollment criteria for the randomized trial, or who were not randomly assigned to one of the treatment groups, were enrolled in the SHOCK trial registry; they form the sample for this report. Between April 1993 and September 1997, 1,190 patients with suspected cardiogenic shock complicating myocardial infarction

Results

The characteristics of the 49 patients with nonhypotensive cardiogenic shock were generally similar to those of the patients with classic cardiogenic shock (Table 1), except that the patients with nonhypotensive cardiogenic shock were significantly more likely to have had an anterior myocardial infarction (P = 0.03). Median times from myocardial infarction to shock or nonhypotensive cardiogenic shock, and time from admission to shock or nonhypotensive cardiogenic shock, were not different. A

Discussion

Our observations suggest that patients with nonhypotensive cardiogenic shock are a unique subset of those with severe left ventricular failure. The condition occurs predominantly in patients with large anterior wall myocardial infarctions. By definition, these patients have clinical signs of peripheral hypoperfusion despite a systolic blood pressure >90 mm Hg without vasopressor support. This indicates ineffective tissue perfusion, and hence a severely depressed cardiac index, and is associated

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Supported by Public Health Service Grants HL50020 and HL49970.

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