Oral Presentation 29th Australian and New Zealand Bone and Mineral Society Annual Scientific Meeting 2019

Effects of calcium supplementation on long-term changes in high sensitivity cardiac troponin I in older women: analysis from a 5 year double-blind randomised controlled trial   (#31)

Joshua R Lewis 1 2 3 , Wai H Lim 3 4 , John T Schousboe 5 , Elizabeth Byrnes 6 , Richard J Woodman 7 , Jonathan M Hodgson 1 3 , Kun (Kathy) Zhu 3 8 , Peter L Thompson 9 , Douglas P Kiel 10 , Richard L Prince 3 8
  1. Edith Cowan University, Perth, WA, Australia
  2. Centre for Kidney Research, School of Public Health, University of Sydney, Sydney, NSW, AUSTRALIA
  3. Medical School, University of Western Australia, PERTH, WA, AUSTRALIA
  4. Department of Renal Medicine, Sir Charles Gairdner Hospital, PERTH, WA, AUSTRALIA
  5. Park Nicollet Osteoporosis Center and HealthPartners Institute, Minneapolis, MA, US
  6. PathWest, PERTH, WA, AUSTRALIA
  7. Flinders Centre for Epidemiology and Biostatistics, Flinders University, Adelaide, SA, AUSTRALIA
  8. Endocrinology and Diabetes, Sir Charles Gairdner Hospital, PERTH, WA, AUSTRALIA
  9. Cardiology, Sir Charles Gairdner Hospital, PERTH, WA, AUSTRALIA
  10. Hinda and Arthur Marcus Institute for Aging Research, Hebrew SeniorLife, Boston, MA, US

Calcium supplements are commonly used to maintain skeletal health, particularly in older women. Concerns have been raised these supplements may modestly increase the risk of myocardial infarctions (MI). Cardiac troponin I (cTnI) tests detect heart muscle cell injury, with high-levels used clinically to diagnose acute MI. Low-levels of cTnI detected using a high-sensitivity assay (hs-cTnI) are a sensitive marker of pathological processes occurring within the myocardium, including myocyte leakage, ischemia and necrosis, and identify individuals at increased long-term risk of clinical MI.(1) We hypothesized that if calcium supplements damaged the heart then levels of hs-cTnI would be elevated in women randomised to calcium vs. placebo. We measured hs-cTnI in baseline (1998) and 5-year (2003) samples stored at -80C from a 5-year double-blind placebo controlled trial of 1,460 women over 70 years randomised to 1.2g of elemental calcium in the form of calcium carbonate or identical placebo. In the 913 women with hsTnI at both time points the mean age of the women was 75.1 ± 2.6 years and the median [IQR] of hs-cTnI was 4.6 [3.7-6.1 ng/L]. There was no difference in the change in hs-cTnI between the calcium vs. placebo controls in intention-to-treat (n=913) or the per-protocol (n=596 taking ≥80% of their tablets) analyses (Table 1). These findings were similar after adjustment for age, dietary calcium and cardiovascular risk factors (p-difference 0.564 and 0.464, respectively). There was no between-group difference in women with a doubling of hs-cTnI levels (n=36) over 5 years (calcium 3.3% vs. placebo 4.5%, Fisher’s exact p-value=0.588). In conclusion, we provide the first high-quality evidence from an RCT that long-term calcium supplementation does not increase circulating levels of cardiac troponin I, a sensitive marker of pathological damage to the heart and future risk of myocardial infarction.5d2bb3f884720-hsTnI+smaller.jpg