Cardiogenic Shock - Diagnosis and Treatment

Chapter 4 / Shock and ACS with ST Elevation 47
increased risk of developing shock had only a 50% chance of developing shock. How-
ever, patients without high-risk variables are very unlikely to develop shock during the
hospitalization, and so this model has a better negative predictive value than positive
predictive value and is better able to identify a low-risk group, which may still be of
clinical benefit.
THERAPY AND PROGNOSIS
Pharmacologic Therapy
The initial treatment of cardiogenic shock resulting from left ventricular dysfunc-
tion requires the intravenous administration of dopamine or other vasopressors, or
perhaps dobutamine if the systemic vascular resistance is high. Volume status should
be optimized, and either diuretics or fluids should be administered if the left ventricu-
lar filling pressure is determined (or estimated) to be high or low, respectively. Oxy-
gen should be administered; if hypoxemia persists or if there is an abnormal mental
status despite supplemental oxygen, mechanical ventilation may be necessary.
Nitrates should be avoided because they may worsen hypotension.
Patients with causes of shock other than left ventricular dysfunction should be
rapidly identified, as their treatment often differs significantly from that given above.
Whether right-heart catheterization is necessary to titrate therapy is controversial.
Although much information can be gleaned from right-heart catheterization, no guide-
lines or algorithms have been established for the management of shock patients based
on the measurements derived from right-heart catheterization. Although studies have
shown that patients have better outcomes when they received more invasive treatments,
including right-heart catheterization, right-heart catheterization has not always been an
independent predictor of improved outcome (9), and other studies have reported a
higher mortality in patients with cardiogenic shock undergoing right-heart catheteriza-
tion (10). The role of right-heart catheterization in patients with cardiogenic shock
remains controversial, but is likely to be most beneficial when noninvasive assessment
of a patient’s hemodynamic status is inconclusive or provides contradictory information.
Thrombolytic Therapy
Thrombolytic therapy clearly reduces the frequency with which shock develops in
patients with ST-segment-elevation myocardial infarction without shock at the time of
treatment (5,6). Tissue plasminogen activator is more effective than streptokinase at pre-
venting the development of shock. However, whether any thrombolytic agent reduces the
mortality when administered to patients who already have shock is controversial.
Because the outcome of cardiogenic shock is closely linked to the patency of the
culprit coronary arteries, it might be expected that thrombolytic therapy would reduce
mortality among patients with shock at the time of treatment (11). However, the results
of randomized trials administering thrombolytic therapy for patients who have already
developed shock has been disappointing. The Gruppo Italiano per lo Studio della
Streptochinasi nell’ Infarto Miocardico (GISSI-I) study (12), a controlled trial compar-
ing streptokinase with control therapy for patients with ST-segment-elevation infarc-
tion, included 280 patients with cardiogenic shock at study entry. The mortality at 21 d
was 69.9% among the 146 patients who received streptokinase and 70.1% among the
134 patients in the group who received control, nonthrombolytic therapy. Registry data
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