Introduction: Previous studies reported a higher mortality rate of females after ST-elevation myocardial infarction (STEMI). According to a recent analysis of 2 prospective cohort studies of survivors 30 days after MI [1] this excess rate remained during the 1^st year after MI and could not be explained by differences in age, cardiovascular and further risk factors, but may be caused by different acute treatment.

The aim of our analysis was to analyze whether there are different treatment procedures and an excess in-hospital mortality rate (IHM) for women with STEMI after adjustment for all risk factors or conditions available in the dataset like age, diabetes (DM), renal insufficiency (RI), CHD, cardiac shock (CS), reanimation and others. For a valid analysis it is necessary to compare cohorts which differ only in sex.

Data: The 2013 PCI dataset of the German Federal Council, containing information about all PCI for Germany and held by the AQUA institute (Göttingen, Germany) was analyzed. Included in the analysis were patients with 1st PCI after STEMI, who were hospitalized in cardiac departments.

Statistical methods: First the two cohorts of men and women were compared for all relevant variables through descriptive statistics. Secondly all patient-clusters with exactly the same risk-/condition-vector were identified. All possible 1:1 exact matchings were included in these clusters and the IHM for all possible exact matchings converge to the result of the weighting for the identified clusters described in this paper. The documented procedures according to the German Procedure Classification (OPS-Code) of both cohorts were compared.

Results: Out of the total cohort of 29,555 patients (7969 females, mean age 69.7 years, 21,586 males, mean age 62.0 years) pairs with identical profile of all factors contained in the database could be identified. The average of all 1:1 matchings with 4772 pairs resulted in the following profile: age 66.1 years, percentage of reduced ejection fraction (<40%) [EF] 5.6, of DM 14.9, of RI 11.7, of heart failure [CHF] 6.4, with CS at start of procedure 1.8. IHM rate was 4.1% for women and 3.6% for men and statistically not significantly different (p=0.2213). Procedures and treatment (195 OPS-Codes) were not different.

Results of the not-matched cohorts showed major differences: IHM was 19.7% for women (n=3777, mean age 72.2 years) and 11.9% for men (n=11,442, mean age 62.9 years). Women had a significantly worse risk factor profile: EF<40%: 22.5 [men 20.6], DM 42.9% [men 31.3], RI 41.4% [men 30.7], CHF 38.0% [men 30.7], CS 15.7% [men 13.3].

Conclusion: After adjustment for age and additional risk factors there is no statistically different IHM rate for women and men in STEMI patients, and acute treatment procedures are identical for both sexes. These results, which are based on a large scale database, are in accordance with results of a smaller study [2]. The impression of sex differences in IHM may be induced by differences in the not-matched cohort. But valid conclusions about differences in treatment or IHM can only be drawn from comparable cohorts.

Literature: [1] Ubrich R et al. (2017) Sex differences in long-term mortality among acute myocardial infarction patients. PLoS ONE 12(10):e0186783.

[2] Eitel I et al. (2012) Sex Differences in Myocardial Salvage and Clinical Outcome in Patients With Acute Reperfused ST-Elevation Myocardial Infarction. Circulation: Cardiovascular Imaging. 2012;5:119-126