Thrombolysis in Acute Myocardial Infarction Complicated by Cardiogenic Shock.
The adverse impact of the development of cardiogenic shock in the setting of acute myocardial infarction was first described by Killip and Kimball in 1967. While the in-hospital mortality rate in patients with myocardial infarction and no evidence of heart failure was only 6%, the mortality rate in those patients who developed cardiogenic shock was 81%. Despite advances in cardiovascular care and therapy since that initial report, including universal institution of cardiac care units, advances in hemodynamic monitoring, new inotropic and vasodilating agents, and even increasing utilization of thrombolytic therapy, the mortality from acute myocardial infarction, when complicated by cardiogenic shock, remains disturbingly high, and cardiogenic shock remains the leading cause of death of hospitalized patients following acute myocardial infarction.The grave prognosis associated with this condition has resulted in increased interest in potential therapeutic interventions, particularly in the area of reperfusion therapy. Several studies suggest that, in contrast to the beneficial effects of thrombolytic therapy in most patient populations suffering acute myocardial infarction, mortality rates are not decreased in those patients with cardiogenic shock at the time of lytic administration. Thrombolytic administration does, however, appear to lead to a modest reduction in the percent of patients with myocardial infarction who will subsequently develop cardiogenic shock during hospitalization.Reperfusion rates with lytic therapy in patients with cardiogenic shock are disappointingly low, in the range of 42-48%, significantly lower than those achieved in patients without cardiogenic shock. These low perfusion rates may, in part, be explained by decreased coronary blood flow and perfusion pressure in patients with left ventricular pump failure.Although promising as adjunctive therapy, it is unclear whether institution of balloon counterpulsation has any long-term benefit in patients with cardiogenic shock treated with thrombolytic therapy. Whether other or additional interventions, such as coronary angioplasty and coronary artery bypass graft (CABG), decrease mortality rates in patients with cardiogenic shock remains to be determined.
Levine
GN
Section of Cardiology, Boston University Medical Center, Boston, MA.
Hochman
JS