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30-Days

6-Months 12-Months

Fig. 6. The temporal relation to survival for patients randomized in the SHOCK trial by treatment strategy (6,280).

sions in 1994 recognized revascularization independently reducing the odds of death by 80% (272). Mortality (n = 837) was also independently decreased by revascularization therapy (62.5 vs 84.3%, p = 0.001) in the Maximal Individual Therapy of Acute Myocardial Infarction (MITRA) study (277). In the GUSTO-I trial, the 30-d mortality was reduced among patients undergoing angioplasty and/or bypass surgery (38 vs 62%, p = 0.001), although revascularization patients were younger with less prior infarction and shorter thrombolytic reperfusion times (278). However, in multivariate logistic regression analysis, an invasive revascularization strategy was independently associated with reduction in 30-d and 1-yr mortality (278,279).

Only two randomized trials of urgent revascularization therapy have been conducted. The Swiss Multicenter trial of Angioplasty for Shock (SMASH) enrolled only 55 patients because of insufficient recruitment (222). The reduction in 30-d mortality noted for the invasive group 69 vs 78%) was not significant.

The SHOCK trial deserves special attention (6). Patients with shock due to predominantly left ventricular dysfunction (ST-elevation or new left bundle-branch block) were enrolled. Notably, 55% were transferred from other hospitals with a median time to randomization equaling 11 h. Over the recruitment period (1993-1998), 302 patients were randomly assigned to an early revascularization strategy (angioplasty [55%] or bypass surgery [38%]) within 6 h of randomization (median = 1.4 h). Thrombolytic therapy (63%) was recommended in the medical stabilization group,and delayed (>54 h) revascularization (angioplasty [14%], bypass surgery [11%]) was recommended if clinically appropriate. Intra-aortic balloon support was recommended (86% in both groups).

At 30 d, the survival advantage (primary end point) observed with early revasculariza-tion did not achieve statistical significance. However, a significant benefit was noted at 6 mo and 1 yr (Fig. 6) (6,280). This benefit appeared to be limited to patients <75 yr of age.

Although the treatment difference in the primary end point did not achieve statistical significance, the trial was somewhat underpowered, and the aggressive treatment

Table 7

ACC/AHA Guidelinesa for Emergency Revascularization for Acute Myocardial Infarction with Cardiogenic Shock

Primary percutaneous interventions (PCI)

Class I

In patients who are within 36 h of an acute ST-elevation/Q wave or new LBBB MI who develop cardiogenic shock, are <75 yr old, and in whom revascularization can be per-

fromed within 18 h of the onset of shock. PCI after thromblysis

Class IIa

Cardiogenic shock or hemodynamic instability. Emergency coronary bypass surgery

Class I

1. Failed angioplasty with persistent pain or hemodynamic instability.

2. At the time of surgical repair of postinfarction ventricular septal defect.

Class Iia

Cardiogenic shock with coronary anatomy suitable for surgery.

a1999 revision (108).

PCI, percutaneous coronary intervention; LBBB, left bundle-branch block; MI, myocardial infarction.

(thrombolysis and balloon counterpulsation) in the medical stabilization group may have mitigated the apparent benefits. The SHOCK registry confirmed similar benefits for an early revascularization strategy (4).

The experimental and clinical importance of multivessel disease in the pathophysiol-ogy of cardiogenic shock has been established (42,43,49). In some studies, multivessel disease and incomplete revascularization have been related to mortality (224,228). In the SHOCK trial, angioplasty was recommended for patients with 1 or 2 vessel disease and bypass surgery for severe triple vessel or left main disease (281). In both the SHOCK trial and registry, mortality was increased in patients undergoing angioplasty with triple vessel disease (223,282). There has been little investigation regarding the role of multivessel angioplasty in the setting of cardiogenic shock, although utilization of stents may allow safer application of this strategy.

Although controversy remains, available evidence supports the application of early revascularization procedures to patients with cardiogenic shock secondary to left ventricular failure (Table 7) (108).

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