The Relationship Between Calcium and Cardiac Calcium Scoring

BACKGROUND:

1. Osteoporosis (op) is a disorder of bone characterized by reduced mineral density and bone mass. The first step in the prevention and treatment of Op is ensuring adequate intake of calcium and vitamin D . While calcium supplementations clearly slow bone loss in both sexes,(1,2) their effects on fracture risk are less certain.(3,4)
2. Experimental data suggest that . vitamin D 25 affects cardiac muscle directly; controls PTH secretion, regulates the rennin-angiotensin - aldosterone system, and modulates the immune system.(5) Vitamin D deficiency has been associated with hypertension; several types of vascular disease and heart failure.
3. Evidence suggests that high calcium intake might protect against vascular disease.

There is evidence that calcium intake might impact on serum lipid concentrations.(6) There is also evidence that calcium supplementation reduces blood pressure,(7) and that CV mortality is lower in hard water areas.(8)

In contrast to the above a recent randomized, placebo controlled trial in 1471 postmenopausal women (mean age 74) reported in the BMJ (2 February 2008) found an increased rate of vascular events in healthy older women receiving calcium supplementation.

Outcome measures were assesed over 5 years and included death, myocardial infarction, , stroke, transient ischaemic attack and development of angina pectoris.A composite end point of major adverse events (MACE= major advrse cardiac events) included myocardial infarction, stroke, or sudden death. MACE was also more common in the calcium group (101 events in 69 women v 54 events in 42 women, P=0.008). Adjudicated myocardial infarction was more common in the calcium group (24 events in 21 women v 10 events in 10 women, relative risk 2.12, 95% confidence interval 1.01 to 4.47).For stroke the relative risk was 1.37 (0.83 to 2.28) and the rate ratio was 1.45 (0.88 to 2.49). The authors concluded that calcium supplementation in healthy postmenopausal women is associated with upward trends in cardiovascular event rates and that this potentially detrimental effect should be balanced against the likely benefits of calcium on bone. (9) Possible mechanisms: The finding of an adverse trend in vascular events with calcium supplementation is not necessarily surprising, since calcium supplements acutely elevate serum calcium levels possibly accelerating vascular calcification, which is predictive of vascular event rates. Multiple observational studies have shown that cardiac event rate increases markedly over several years of follow-up with increasing levels of CAC(Coronary artery calcium) independently of conventional risk factors. CAC scoring has been advocated asa screening test for coronary disease risk in individuals at intermediate risk for coronary events