Does diabetes matter after 75? Mortality in the elderly with acute coronary syndrome

Introduction and aim

Elderly patients with acute coronary syndrome (ACS) and diabetes mellitus have a worse prognosis than non-diabetic counterparts, characterized by higher in-hospital mortality, adverse cardiovascular events, and complications such as extensive coronary disease and multimorbidity.

The aim of our study was to investigate differences in intrahospital mortality rates between diabetic and nondiabetic elderly patients (75 years or older) with ACS, as well as differences in routinely measured biomarkers and left ventricular ejection fraction (LVEF).

Results

We included 1036 consecutive patients, aged 75 years or older (80.9±4.4), with ACS in our observational study. 488(47.1%) were female, 548 (52.9%) were male, and 371 (35.8%) were diabetic. Myocardial infarction with ST-segment elevation (STEMI) was diagnosed in 40.69% of patients; myocardial infarction without ST-segment elevation (NSTEMI) in 53.33%; and non-stable angina pectoris in 5.98%.

Typical chest pain was similarly distributed between patients with and without diabetes at admission (68.73 vs. 69.02%, p=0.9). Patients with diabetes had significantly higher glycemia levels at admission (11.34±5.32 vs. 7.87±3.49 mmol/L, p<0.001). Troponin I levels (1.24 ± 10.195 vs. 1.18 ± 9.21 ng/mL) and brain natriuretic peptide (BNP) levels (1208.08 ± 812.6 vs. 1350.15 ± 560.35 pg/mL) were not statistically different between patients with and without diabetes. LVEF was similar between diabetics and elderly nondiabetic patients (46.11±13.3 vs. 46.42±13.65%). 36% of diabetics and 25.3% of non-diabetics had a previous myocardial infarction (p<0.001). Previous PCI was slightly more frequent in diabetics than in non-diabetics (18.7% vs. 15%, p=0.139). PCI was performed in 30.19% of diabetics and 31.28% of nondiabetic patients. 178 patients died during hospitalization, and mortality was slightly higher in diabetic patients (19.14% vs. 16.09%), p=0.213.

In multivariable logistic regression analysis that included the aforementioned clinical, laboratory, and echocardiographic findings, as well as PCI status, we found that higher glycemia at admission (OR 1.096, CI: 1.045–1.150, p<0.001) and lower LVEF (OR 0.952, CI: 0.924–0.981, p<0.001) were significant predictors of in-hospital mortality in diabetic patients. In nondiabetic patients, glycemia at admission (OR 1.221, CI:1.138–1.310, p<0.001), lower LVEF (OR 0.970, CI: 0.949–0.998, p<0.01), and non-performing PCI (OR 0.308, CI: 0.197- 0.547, p<0.001) were associated with increased mortality rates.

Conclusion

At age 75+, elderly diabetics with acute ACS have similar outcomes to non-diabetics. Hyperglycemia at admission and lower LVEF are strong predictors of worse outcomes in the elderly, irrespective of diabetes. Non-performing PCI is associated with 70% increase in mortality in non-diabetic elderly patients. Chronological age in ACS, when combined with or without diabetes, should not limit evidence-based interventions.