Chapter 4 / Shock and ACS with ST Elevation 53
Clinical and Economic Implications
The treatment of patients with cardiogenic shock imposes a large economic burden
on health care systems; the 5–10% of patients with shock consume more resources
than the care of all other patients with acute myocardial infarction who do not develop
shock. Nonetheless, the utilization of such intensive resources appears appropriate,
given that when patients with shock survive the initial hospitalization, the outcome is
good; 85% of shock patients who survive 30 d will be alive at 1 yr (26). Given the
high early mortality of even those patients with shock who receive early revascular-
ization, the best approach would be to develop therapies that prevent shock from
occurring in the first place. Unfortunately, other than administering early reperfusion
therapy to patients with acute myocardial infarction, such therapy has not yet been
discovered. If such therapy is developed, it remains difficult to identify patients who
would benefit from it the most. Even the previously described algorithms to identify
patients with acute coronary syndromes (with or without ST-segment elevation) at
highest risk of developing shock are limited because more than half of even such
high-risk patients will not develop shock, even when only standard, currently avail-
able therapies are administered.
Right Ventricular Infarction
Because of the important differences among the etiology, diagnosis, and prognosis
of patients with cardiogenic shock resulting from the right versus left ventricular dys-
function, we will address the entity of right ventricular infarction separately. Right ven-
tricular infarction, as detected by right precordial ST-segment elevation or by
echocardiography, occurs in approximately one of every three patients with acute infe-
rior ST-segment-elevation infarction; however, it is hemodynamically significant in
only half of the patients (34–39). Prompt diagnosis is important, because cardiogenic
shock resulting from right ventricular infarction is generally reversible. However, ther-
apies that are often administered to patients with shock resulting from left ventricular
dysfunction must be avoided, such as nitrates and diuretics, and others often avoided in
patients with left ventricular dysfunction should be administered, such as normal
saline, large amounts (several liters) of which may be required.
THROMBOLYTIC THERAPY FOR RIGHT VENTRICULAR INFARCTION
As with cardiogenic shock resulting from left ventricular infarction, thrombolytic
therapy is able to reduce the development of shock in inferior ST-segment-elevation
infarction due to right ventricular dysfunction (40,44).
Patients with right ventricular infarction have larger infarction, greater impairment of
left ventricular function, and more complications, including cardiac arrest and heart block,
than patients without right ventricular infarction and cardiogenic shock (42). Therefore, the
prompt recognition of right ventricular involvement during inferior infarction identifies a
subset of patients with a worse prognosis who are particularly good candidates for inter-
ventions aimed at myocardial salvage.
PROGNOSIS OF RIGHT VENTRICULAR INFARCTION COMPLICATED BY SHOCK
If patients with right ventricular infarction survive the initial hospitalization, most
(although not all) studies suggest that they do not have a significantly higher mortality in
the year following discharge (44,43,44). In fact, the majority of right ventricular wall
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