3-10-99
The SHOCK Trial

	Mortality from acute heart attack with 
cardiogenic shock has been as high as 80-90%. 
Recently, aggressive intervention, including
revascularization with angioplasty and bypass, has 
increased survival. Does early revascularization in 
patients with heart attack and cardiogenic shock 
further reduce mortality?
	SHOCK was a trial of emergency bypass/
angioplasty versus medical stabilization in patients
with heart attack who developed cardiogenic shock. The 
theory was that early revascularization would produce a 
20% reduction in all-cause 30-day mortality.
	The SHOCK Trial was a multicenter study enrolling
patients from 1993 to 1998. Patients had acute heart 
attack and developed cardiogenic shock within 36 hours. 
Within 12 hours, they were randomized to either emergency 
revascularization (ERV) or medical stabilization (MS). 
Patients randomized to ERV had angioplasty or bypass 
within 6 hours. Patients randomized to MS received clot-
buster therapy and then had angioplasty or bypass more 
than 54 hours later.
	Primary endpoint was 30-day all-cause mortality. 
Secondary endpoints included: 6 and 12 month all-cause 
mortality; 2 week change in left ventricular function; 
and quality of life and functional status.
	RESULTS: Of all patients screened, only 26% of 
patients with heart attack and shock were eligible, 
with a 56% mortality rate. A total of 302 patients 
successfully participated. The average age was 66 and 
32% were women. Of the 152 patients who were randomized 
to the ERV group, 97% had angiography, following which 
87% had revascularization procedures - 48% had 
angioplasty versus 38% who had bypass surgery. Of the 
150 patients randomized to the MS group, only 4% had
revascularization in less than 54 hours. 22% had later 
revascularization procedures.
	At 30 days, the all-cause mortality rate was 46% 
in the ERV group versus 56% in the medical stabilization
(MS) group - a 9% absolute risk reduction.
	At 60 days, mortality was lower in the ERV group 
(54%) compared to the MS group (68%). Adverse events, 
including stroke, angina, sepsis, hemorrhage, and 
refractory shock, were similar in both groups, except 
that acute kidney failure occurred more often in the MS 
group. Age had an effect on outcome - younger patients
(less than 75 years) had a greater benefit from ERV,
than older patients (older than 75 years), who had a 
greater benefit from MS.
	At 6 months, younger patients in the ERV group had 
less mortality (48%) than those in the MS group (69%),
suggesting a lesser effect of ERV with increasing age.
	Angioplasty success was defined as less than 50% 
residual stenosis, more than 20% reduction of stenosis, 
and opened artery with TIMI grade 2-3 flow.
	In the ERV group, 76% had successful angioplasty.
As expected, stent and abciximab (drug) use increased with 
time. At 30 days, 147 of 152 patients in the ERV group 
had angiography, with a mortality rate of 45%. 57 had 
bypass, with a mortality rate of 42%.
	CONCLUSIONS: The SHOCK Trial did not show the 
expected 20% reduction in mortality rates for patients 
having ERV compared to patients receiving MS. However, 
these results may be affected by the fact that MS patients 
had very intensive medical treatment and later 
revascularizations. 6 month mortality is decreased in 
patients receiving ERV compared with IMS. Only age had a
significant impact on treatment at 30-day and 6-month 
follow-up.