https://doi.org/10.1007/s00392-025-02625-4
1Deutsches Herzzentrum München Klinik für Herz- und Kreislauferkrankungen München, Deutschland; 2Deutsches Herzzentrum München München, Deutschland
Background: Age-related immunosenescence is characterized by diminished adaptive immunity and increased persistent low-grade inflammation. This "inflamm-aging" may influences the immune response following an acute ST-segment elevation myocardial infarction (STEMI) and impact the course of MI.
Objective: To examine "inflamm-aging" in acute STEMI patients, by comparing trends in leukocytes, monocytes and neutrophils in two age groups, ≥65 years and <65 years, as well as associating it with infarct size and myocardial salvage after primary PCI.
Methods: A retrospective analysis was performed on a cohort of 631 patients divided into two groups: older adults (≥65 years, n=293, mean age=76.86, 68% male) and younger adults (<65 years, n=338, mean age=54.62, 83% male). We assessed levels of leukocytes, monocytes, and neutrophils during the first five days post-STEMI, comparing both inter-group and intra-group variations. These findings were validated using a second cohort of 1,156 patients: older adults (≥65 years, n=491, mean age=76 years, 64% male) and younger adults (<65 years, n=665, mean age=53 years, 86% male). Troponin T and CK-MB values were available in both cohorts as enzymatic surrogates for infarct size.
Results: Older adults showed significantly lower leukocyte counts on admission [Median (Interquartile Range)] [older: 12.45 [109/l] (IQR: 5.88) vs. younger: 13.90 [109/l] (IQR: 5.45), p=0.0002] and Day 1 [older: 11.20 [109/l] (IQR: 5.15) vs. younger: 11.60 [109/l] (IQR: 5.18), p=0.0187]. Leukocyte count continued to be lower in older adults from Day 2 to Day 5 although without statistical significance. Within-group comparisons in the older adults showed a significant decrease in the inflammatory response from admission to Day 1 (p=0.0001) and from Day 1 to Day 2 (p<0.0001), but not in the following days. Monocyte levels were comparable between the groups, however, neutrophils, while not differing at the time of admission, showed significantly higher levels in the older group from Day 1 to Day 5.
Regarding STEMI-magnitude, peak CK-MB levels were significantly lower in the older adults [older: 142.5 U/l (IQR: 239.45) vs. younger: 168 U/l (IQR: 301.6)], while peak troponin T levels did not differ significantly. These results were replicated in the second cohort.
Conclusion: Our study demonstrates distinct immune responses to STEMI between younger and older patient populations. In elderly patients, this immune response is attenuated, evidenced by a reduced initial inflammatory peak (measured by leukocyte levels at admission) and a more rapid resolution of inflammation (measured by leukocyte levels on day 3) following STEMI. These immune response variations are correlated with smaller infarct sizes, as indicated by lower peak CK-MB levels in older adults. Our findings suggest that chronic, low-grade inflammation may modulate the systemic immune response to myocardial injury, potentially influencing the progression and clinical course of MI.