Friday, February 25, 2011


Cardiologist , and I am sure the general population as well, is very interested in what triggers a heart attack. How come patients with severe coronary artery disease, some get a heart attack and maybe die, while others with similar blockages have nothing happen to them and they live to good old age and die from a motor vehicle accident?
What triggers a heart attack?
I remember when I was a young cardiologist, about 20years ago, I did a coronary angiogram on a young man, in his 50s for evaluation of a positive stress ECG. It revealed that he had 3 vessel CAD. So I referred him for coronary artery bypass surgery. Those were the days before PTCA in Malaysia. About 10 years later, another man cam to see me. He also had 3 vessel disease CAD. When I suggested that he goes for CABG, he declined saying that he wanted medical therapy and showed my angiogram report and diagram, of the previous patient who had 3 vessel disease, refused CABG, and was still surviving, and well. The point is that, there are many out there with 3 vessel disease, some discovered and some undiscovered, who go along in life, apparently well. The difference is that some 3 vessel ( or even 1 vessel ) disease may meet a trigger and result in a heart attack, while others have no triggers and so live to good old age.
What then triggers a heart attack?
This has been the subject of extensive medical research, as it may hold the key to who is most at risk and who is not.
In the 23rd Feb issue of Lancet, there is an article by Dr Tim Nawrot et al, ( from Belgium ) on the subject. In a paper entitled "Public health importance of triggers of myocardial infarction: A comparative risk assessment. " Dr Nawrot and colleagues collected epidermiological data from 36 large epidermiological studies on this subject. They concluded that while on an individual basis, cocaine is probably the most important trigger for a heart attack. On a community base, air pollution and traffic exposure, is probably the most important. They figured that air pollution and traffic exposure forms 5-7% the risk of triggering a heart attack. Of course the other triggers in the community / population includes, heavy meals, anger, negative and positive emtions, alcohol, coffee and physical exercise.
From a cardiac standpoint, what this means is that for those of us with some coronary artery cholesterol blockages, the blockages are stable and remain silent, or cause us occasional exertional chest pains. But should we meet a trigger / trigger event, that stable cholesterol plaque, may rupture, exposing the underlying cholesterol accumulation, to blood following pass it ( it is exposed to the blood because the plaque has ruptured ). And when blood meets cholesterol, blood clots instantly. The blood clot obstructs the whole artery lumen, so blood can no longer flow downstream, and the heart muscle beyond the obstruction dies, as they become devoid of oxygen and nutrients. The death of the heart muscle, constitutes a heart attack.
All this sequence of events are because something has triggered the plaque to rupture. So when you are in a polluted environment, with some alcohol and positive or negative emotions, becareful. Whats more, this situation may follow a heavy meal. Add to it, a bit of sex. Then we are just asking for it.
Of course medical science is working very hard to see if we can be a bit more specific, and whether there could be other warnings to allow us to prevent. So far, we are still not sure.
I suppose asking us all to avoid traffic exposure, pollution, emotional upsets, heavy meals, sex etc, is impossible. Better not live then, as some of my patients tell me.
Some even believe that a massive heart attack is a "good" death.
You have been warned.

No comments: