Elsevier

American Heart Journal

Volume 149, Issue 6, June 2005, Pages 1128-1134
American Heart Journal

Clinical Investigation
Interventional Cardiology
Outcome of patients aged ≥75 years in the SHould we emergently revascularize Occluded Coronaries in cardiogenic shocK (SHOCK) trial: Do elderly patients with acute myocardial infarction complicated by cardiogenic shock respond differently to emergent revascularization?

https://doi.org/10.1016/j.ahj.2005.03.045Get rights and content

Background

In the SHOCK trial, the group of patients aged ≥75 years did not appear to derive the mortality benefit from early revascularization (ERV) versus initial medical stabilization (IMS) that was seen in patients aged <75 years. We sought to determine the reason for this finding by examining the baseline characteristics and outcomes of the 2 treatment groups by age.

Methods

Patients with cardiogenic shock (CS) secondary to left ventricular (LV) failure were randomized to ERV within 6 hours or to a period of IMS. We compared the characteristics by treatment group of patients aged ≥75 years and of their younger counterparts.

Results

Of the 56 enrolled patients aged ≥75 years, those assigned to ERV had lower LV ejection fraction at baseline than IMS-assigned patients (27.5% ± 12.7% vs 35.6% ± 11.6%, P = .051). In the elderly ERV and IMS groups, 54.2% and 31.3%, respectively, were women (P = .105) and 62.5% and 40.6%, respectively, had an anterior infarction (P = .177). The 30-day mortality rate in the ERV group was 75.0% in patients aged ≥75 years and 41.4% in those aged <75 years. In the IMS group, 30-day mortality was 53.1% for those aged ≥75 years, similar to the 56.8% for patients aged <75 years.

Conclusions

Overall, the elderly randomized to ERV did not have better survival than elderly IMS patients. Despite the strong association of age and death post-CS, elderly patients assigned to IMS had a 30-day mortality rate similar to that of IMS patients aged <75 years, suggesting that this was a lower-risk group with more favorable baseline characteristics. The lack of apparent benefit from ERV in elderly patients in the SHOCK trial may thus be due to differences in important baseline characteristics, specifically LV function, and play of chance arising from the small sample size. Therefore, the SHOCK trial overall finding of a 12-month survival benefit for ERV should be viewed as applicable to all patients, including those ≥75 years of age, with acute myocardial infarction complicated by CS.

Section snippets

Trial design

The design of the SHOCK trial has been previously reported.8 Briefly, from 1993 to 1998, 302 patients with CS within 36 hours of MI and within 12 hours of shock diagnosis were randomly assigned to IMS or ERV in 36 participating centers. It was recommended that patients assigned to ERV who had 1- or 2-vessel disease undergo percutaneous coronary intervention (PCI) of the culprit lesion only, and that patients with severe 3-vessel or left main disease undergo emergency surgery, defined as within

Clinical characteristics

In patients aged ≥75 years, a trend was observed for a higher proportion of females, anterior wall MI location, and a lower rate of prior congestive heart failure in the group assigned to ERV (Table I). As expected per protocol, more patients randomized to IMS received thrombolytic therapy. In addition, IMS patients had undergone prior coronary artery bypass grafting more frequently than patients in the ERV group.

Left ventricular function and angiographic characteristics

Elderly patients assigned to ERV had a lower mean LVEF than the elderly in the IMS

Discussion

In the SHOCK trial, an international, multicenter randomized study of emergency revascularization in CS, we found that the response in the elderly to ERV appeared to differ from the younger cohort. The detailed analysis reported in this article identifies factors that may explain this apparent difference.

We observed that the elderly assigned to ERV in the SHOCK trial had a lower mean LVEF than those assigned to IMS. We have previously reported that LVEF measured early during shock presentation

References (21)

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    Citation Excerpt :

    While there was a significant benefit of revascularization for 30-day mortality when compared with initial medical stabilization in those aged <75 years (relative risk [RR] 0.73; 95% CI, 0.56-0.95), there was no such apparent benefit observed in the small cohort of patients who were age 75 years or older (RR 1.41; 95% CI, 0.95-2.11; Pinteraction = .01). The lack of benefit was likely due to differences in baseline characteristics (lower ejection fraction in the revascularization group) and the play of chance arising from the small sample size of the elderly subgroup (56 patients).16 However, in the SHOCK registry there was a significantly lower mortality rate in those receiving revascularization when compared with those treated conservatively, including in the elderly (RR 0.46; 95% CI, 0.28-0.75; P = .002).17

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This study was supported by grants R01 HL50020 and HL49970 from the National Heart, Lung, and Blood Institute, National Institutes of Health, Bethesda, Md.

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