A large study has deemed SP-D, a blood protein, to be “a good predictor” of cardiovascular disease. Researchers say that circulating SP-D levels were clearly associated with heart disease and total mortality in patients who had coronary artery disease.
In the lungs, SP-D is part of the body’s defensive response to substances inhaled each day. Levels of SP-D rise when the lungs are inflamed and not working well (e.g. catching a cold or the flu) and also in those who smoke or develop a chronic lung condition.
In healthy people with normal lung function, blood levels of SP-D are low, but when lung function is impaired (as with infections, smoking or COPD), SP-D leaks from the lungs into the blood and then into the circulation, increasing the risk of atherosclerosis (hardening of the arteries).
To determine if SP-D is linked to heart disease and death, the researchers studied it in people with suspected coronary artery disease and in a group of ex- and current smokers with mild airflow restriction.
In the first group, those who died (30%) had significantly higher SP-D levels than those who survived. Those with the highest SP-D levels had an over 400% higher risk of death by heart disease than those with the lowest levels.
In the group of current and ex-smokers, again, SP-D levels were higher in those who died or were hospitalized for heart disease. The researchers say there is a “strong” link between SP-D levels and heart disease. They can’t be sure if the SP-D levels contribute to heart problems, but they can be sure that they at least indicate potentially serious heart issues.
In the fight against heart disease, any help is good help.