Why are seemingly healthy, active and young people suffering from serious heart trouble these days?
Part of the answer could lie in lipoprotein (a) or Lp (a), a subvariant of low-density lipoprotein (LDL; also called bad cholesterol) especially among South Asians and Indians. Elevated Lp (a) levels put one at increased risk of heart attack, especially in asymptomatic people.
According to an article published by the American College of Cardiology, based on a study (Don P Wilson et al., 2019) published in the Journal of Lipid Clinicology, at least 20 per cent of the total world population has elevated Lp (a) levels and highlights the need to look beyond traditional lipid profile for cardiac risk assessment. The article has also pointed out that there is a three-to-four-fold increase in heart attack risk, threefold increase in valvular aortic stenosis and a fivefold increase in coronary artery stenosis depending on Lipoprotein (a) levels.
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What is Lipoprotein (a) cholesterol
Lp (a) — pronounced Lipoprotein little ‘a’ — is a ‘genetic hybrid’ variety of LDL cholesterol. Like all other lipoprotein formations, this one is also mainly responsible for cholesterol transportation in our blood. And just like LDL, Lp (a) also does not get filtered out of the body easily and gets stuck to the arterial wall forming vascular blockages. Lp (a) also plays a major role in plaque formation, arterial stenosis (narrowing), inflammation and blood clot formation, making it a more serious threat than LDL (or bad cholesterol). Lipoprotein (a) is almost completely inherited (more than 90 per cent) and has minimal connection with diet and lifestyle.
“Lipoprotein (a) is much more dangerous than regular LDL or bad cholesterol. It is found to be more common in South Asians, including Indians. In 2018, Lp(a) was acknowledged as an independent risk factor for causing heart attacks by American and European cardiac health organisations, including the American College of Cardiology (ACC) and American Heart Association (AHA) as opposed to the earlier theory that only LDL or bad cholesterol was a causative agent for atherosclerosis and related complications, including heart attacks,” says Dr Enas A Enas, Illinois-based cardiologist and President of Coronary Artery Disease among Asian Indians (CADI) Research Foundation, in a telephonic conversation with Happiest Health. Dr Enas is also among the premier cardiologists globally to research and publish about the Lp (a) in the Indian Heart Journal in recent years (Enas A Enas et al.,2019). He was also part of the numerous research teams to establish the Lp (a) the link in heart attack and cardiovascular diseases especially in South Asians in the early 1990s.
Compared to LDL, Lp (a) has a higher affinity to stick on to arterial walls, cause lesions and also form blood clots and thereby greatly increases the risk of heart attack. Elevated Lp (a) levels on their own could also cause cardiovascular issues and the extent of cardiac blockages would be more serious if the individual has both high levels of Lp (a) and LDL.
“Unlike LDL, Lp (a) is genetically acquired by the individual. It has nothing to do with our diet patterns; so Lp (a) cannot be controlled through dietary and lifestyle alterations as in the case of regular cholesterol. In fact, by the time an individual attains the age of five, he or she will attain the maximum level of Lp (a) on the basis of their genetic makeup and it will remain constant throughout their life,” Dr Enas adds.
The ACC and the AHA now prescribe 50 mg/dL as a safe upper limit for Lp (a). However, some doctors like Dr Enas say it is better if it is below 30 mg/dL.
Another cause of concern is that none of the medicines, including statins, are found to have any direct impact on lowering Lp (a) levels; research is under way for effective pharmacological interventions.
Lipoprotein (a): The genetic cholesterol variant
The ACC in a 2019 article pointed out that 80 to 90 per cent of Lp(a) levels are genetically inherited and the Apo (a) gene responsible for this is inherited from the parents. The Lp (a) patterns are found right at the stage of infancy, i.e., by the age of one or two, and it could attain full levels by the age of five. It is believed that Lp (a) might also have some crucial role to play in wound healing and bleeding control, especially during childbirth since it has a very high affinity to forming blood clots. The study has also pointed out a link between Lp(a) atherosclerotic cardiovascular diseases and aortic stenosis. One of the theories is that Apo (a) particle attached with Lp (a) is the main reason for its blood clot formation as it has been found to inhibit fibrinolysis, which essentially is an internal enzymatic reaction that keeps internal blood clotting under check to ensure that it doesn’t result in any circulatory complications, including heart attacks, as pointed out in a review article by John C Chapin and Katherine A. Hajjar in Blood Reviews journal in 2015 .
Prof Dr Partha Sarathee Banerjee, Consultant Cardiologist, Manipal Hospital, Kolkata, explained to Happiest Health the role played by Lp (a) in the formation of coronary plaques and subsequently triggering stenosis and lesions on the arterial walls that would lead to calcification and finally how Lp (a) could lead to serious blood coagulation and circulatory blockages by inhibiting fibrin-dependent activities.
He said that elevated serum Lp (a) is an independent predictor of coronary artery disease and myocardial infarction.
Familial hypercholesterolemia and lipoprotein (a)
Familial hypercholesterolemia (a condition where the individuals have high cholesterol levels in their blood due to genetic factors) and elevated Lp (a) levels are among the two major genetic factors that are bad news for the heart. In such cases, people are often advised to take standard lipid profile tests at least once annually.
But here’s the problem: conventional lipid profile tests look for LDL, HDL and triglyceride levels but do measure Lp (a) levels.
“An individual could have extremely healthy cholesterol levels and yet have high Lp (a) level, which will make them vulnerable to cardiac complications, including heart attacks. Technically, Lp (a) levels will be known through a simple blood test, and it is a once in a lifetime test, which could be done any time after the age of five,” Dr Enas says.
According to the ACC, Lp (a) levels could result in a three to four-fold increase in heart attack (myocardial infarction) risk and a five-fold increase in coronary artery stenosis (narrowing and plaque formation).
Get your Lp (a) levels checked
Dr Enas says that high levels of genetic Lp (a) when combined with unhealthy lifestyle and general dietary preferences among South Asians make them extremely vulnerable to cardiac complications.
“Knowing Lp (a) levels is vital as it would equip both the doctor and the individual to choose the most effective strategy to minimise cardiac risks. It will also help us to effectively prevent many cases of heart attacks,” Dr Enas says.
Dr J Karthick Anjaneyan, Consultant and Interventional Cardiologist, Gleneagles Global Health City, Chennai, reiterated to Happiest Health that Lp (a) is more dangerous than LDL because of the presence of apolipoprotein compound in it, which forms cardiac blockages. He also added that Lp (a) levels are now being constantly screened during cardiac health check-up these days.
Lowering Lipoprotein (a)
Dr Banerjee also points out that some of the recent cardiac research findings suggest that Lp (a)-lowering therapy might be in the offing, which could prove beneficial for high-risk groups. He also suggested that a future therapeutic approach to Lp (a) could include apheresis (a blood purification process) among the vulnerable group in order to reduce any major coronary event.
