Abstract P349: Kidney Function Modifies the Positive Association of Troponin With 30 Day Mortality After Myocardial Infarction

Introduction: Increased levels of cardiac troponin at the time of myocardial infarction (MI) have been shown to predict mortality. However, troponin is renally cleared and kidney function itself impacts mortality. We tested the hypothesis that baseline kidney function modifies the relationship between peak cardiac troponin I ratio (cTnI-R) and 30 day mortality after MI. Methods: Data from the Veterans Health Administration was used to create a national sample of hospitalized Veterans with a discharge diagnosis of MI between 2002 and 2015. The peak cTnI-R, calculated as the highest cTnI during the hospitalization compared to the upper limit of normal for each assay, was used as a proxy for the date of the MI event. Veterans with a history of cancer or blood vessel surgery 5 days before peak cTnI were excluded. The closest estimated glomerular filtration rate (eGFR) measured within 2 years prior to hospital admission was used as a marker of baseline kidney function. We created quartiles of peak cTnI-R and clinically relevant levels of eGFR (2 ) and fitted Cox regression adjusting for calendar year, age, length of hospital stay, region, diabetes, major mental health conditions and baseline use of diuretics, anti-hypertensives and anti-lipemics. We used subjects in the first quartile of troponin with eGFR of 60+ as common reference. Results: Among 56,073 Veterans hospitalized for MI, mean age was 67 and 98% were men. During 28 days mean follow up, 4,533 deaths occurred. 30 day mortality steadily increased across quartiles of peak cTnI-R; however, the increase in mortality was higher in eGFR below 30, suggesting effect modification of troponin-mortality relation by eGFR (p for interaction between eGFR and troponin 0.03) (Figure). Conclusions: Our data show that the positive relation of troponin with 30 day mortality post MI is modified by kidney function. Veterans with impaired kidney function carry a higher risk of 30 day mortality after MI compared to those with normal eGFR for a given troponin quartile.