Coronary Artery Disease
Usefulness of the Admission Shock Index for Predicting Short-Term Outcomes in Patients With ST-Segment Elevation Myocardial Infarction

https://doi.org/10.1016/j.amjcard.2014.07.062Get rights and content

Highlights

  • Patients with shock index (SI) ≥0.7 had greater short-term mortality after ST elevation myocardial infarction.

  • SI ≥0.7 was an independent risk factor of poor short-term outcomes after ST elevation myocardial infarction.

  • SI had modest predictive value for 7-day all-cause mortality.

Current risk scores of ST-segment elevation myocardial infarction (STEMI) need sophisticated algorithm and were limited for bedside use. Our study aimed to evaluate the usefulness of admission shock index (SI) for predicting the short-term outcomes in patients with STEMI. Included were 7,187 consecutive patients with STEMI. The admission SI was defined as the ratio of admission heart rate and systolic blood pressure. Patients were divided into 2 groups with SI <0.7 and ≥0.7, respectively, based on the receiver operating characteristic curve analysis. The major end points were 7- and 30-day all-cause mortality. Of 7,187 patients, 5,026 had admission SI <0.7 and 2,161 had admission SI ≥0.7. Those who presented with SI ≥0.7 had greater 7- and 30-day all-cause mortality and major adverse cardiovascular events than patients with SI <0.7. After multivariate adjustment, patients with SI ≥0.7 had a 2.2-fold increased risk of 7-day all-cause mortality (hazard ratio 2.21, 95% confidence interval [CI] 1.71 to 2.86) and 1.9-fold increased risk of 30-day all-cause mortality (hazard ratio 1.94, 95% CI 1.54 to 2.44). Moreover, admission SI ≥0.7 was also associated with 1.6- and 1.5-fold increased risk of 7- and 30-day major adverse cardiovascular events (hazard ratio 1.63, 95% CI 1.36 to 1.95 and hazard ratio 1.47, 95% CI 1.24 to 1.74, respectively). The C statistic of admission SI for predicting 7- and 30-day all-cause mortality was 0.701 and 0.686, respectively, compared with 0.744 and 0.738 from the Thrombolysis In Myocardial Infarction risk score. In conclusion, admission SI, an easily calculated index at first contact, may be a useful predictor for short-term outcomes especially for acute phase outcomes in patients with STEMI.

Section snippets

Methods

This is a retrospective study of consecutive patients with acute STEMI within 12 hours from symptom onset from 2001 to 2004 in 247 hospitals in China. Although it is a retrospective study, data were collected prospectively. STEMI was defined as following: chest pain or equivalent symptoms in combination with dynamic electrocardiographic changes consistent with STEMI (in the presence of ST elevation >0.1 mV in ≥2 extremity leads, >0.2 mV in ≥2 precordial leads, or accompanying with left bundle

Results

Of 7,510 patients, 323 were excluded because of incomplete data or nonsinus rhythm at admission, and 7,187 remaining patients were analyzed. The best cutoff of SI for predicting 7-day all-cause mortality was 0.7 by receiver operating characteristic curve, and the sensitivity and specificity were 59.0% and 74.4%, respectively. With this threshold, 5,026 patients had normal admission SI (<0.7) and 2,161 patients had elevated admission SI (≥0.7).

Table 1 lists the baseline characteristics of the

Discussion

The main findings of this study are as follows. First, those who presented with elevated admission SI (≥0.7) had greater incidence of short-term cardiovascular events compared with those with normal admission SI (<0.7) in patients with STEMI. Second, after multivariate adjustment, elevated admission SI (≥0.7) was still an independent risk factor predicting the short-term outcomes. Third, the prognostic discriminatory capacity of admission SI is moderate for 7-day all-cause mortality but limited

Acknowledgment

The authors thank investigators from every hospital for providing data, and all the study coordinators, as well as patients who participated in the multicenter study.

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