( By Dr Ramesh Kapadia )
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Some Reflections On Coronary Heart Disease
The sudden death which occurs in Coronary Heart Disease has spread its mantle of fear over the whole complex problem of Coronary Heart Disease. However, it needs emphasis that a large number of Coronary Heart Disease patients even after the attack live a meaningful life for a long time. Simple linear mathematical relationships govern most of our thinking in medicine. The dynamic human body does not follow these linear relationships, and doctors tend to predict the unpredictable!
The narrowing of the coronary arteries per se does not inevitably result in heart attack. The narrowing of the coronary arteries gradually progresses to a complete block with the passage of time. However, occluded vessel does not pose the risk of a heart attack and its complications or even of a long term detrimental effect on heart function. The complete occlusion resulting in heart attack is always the result of a blood clot causing obstruction of a near normal vessel. In the absence of a heart attack, the narrowed coronary artery does not alter the long term changes in the total left ventricular function despite evidence of the exercise induced signs and symptoms of myocardial ischoemia. It has been shown in some brillaint scientific studies that brief periods of ischaemia ( so called silent ischaemia) trigger adaptive changes in the heart, protecting it from the future major failure of blood supply. This is called ischaemic preconditioning. In this way silent ischaemia may even prove beneficial to the heart.
No study has shown that the coronary angiography is required as a 'gold standard' test in the diagnosis of Coronary Heart Disease before giving the patient medical therapy. On the contrary, the randomised trials have demonstrated that nitrates, aspirin, low fat vegetarian diet, beta- blockers, calcium-blockers and angiotensin converting enzyme-inhibitors can save many lives. The Coronary Artery Surgery Study (CASS) of U.S.A. clearly shows that angiography should be done only to plan the operation after the decision to operate is taken and not as the basis of diagnosis. If angiography is done before that decision, there is a risk of the patient being scared by the doctors that he is sitting on a 'volcano' which may kill him at any time.
For a large number of patients undergoing bypass surgery there is no evidence that it improves their prognosis compared to those managed by medical means. Disturbed coronary anatomy except for the left main artery disease does not predict prognosis when the left ventricular function is good. Even when those with left main artery disease who declined the surgery and were followed up for over a decade, the annual mortality was only 1.3% which is not significantly higher than that of the general population and it was 0% for single and double vessel disease. When obstructed internally coronary arteries are capable of remodelling themselves and enlarging at the site of obstruction. This puts us in mind of our father of medicine, Hippocratis's observation that the body has inherent capacity to heal itself.
In the patients who run the risk of sudden death as a result of the coronary artery disease bypass surgery by and large does not afford any protection. Even the usual claim of better quality of life after the bypass needs appraisal as new thoughts on the quality of life demand more critical appraisal of how it is measured. For angioplasty the restenosis rate may be as high as 50% which is due to the increased cellular and fibrous growth (fibrocellular intimal hyperplasia) for which there is no easy solution in sight.
In conclusion, one definite indicatin for revascularisation is intractable (not responding to medical therapy) chest pain and another where there is poor left ventricular function with anatomic changes such as aneurysm, ventricular septal defects or mitral leaks, making life miserable for the patients. The coronary bypass surgery is a boon to these very ill patients. We should encourage revascularisation based on the patient's symptoms and disabilities rather than on angiograms with so called critical narrowing of coronary arteries.
All too frequently requested angiograms and advice for angioplasty and bypass surgery by the well intentioned highly qualified doctors is due to a different perception of the disease and its probable outcome in a particular patient. There is indeed a need for rethinking in this field. *
* Doctors as well as the lay readers are requested to see the article by Dr. B.M. Hegde, Kasturba Medical College, Mangalore, India, published in the Proceedings of the Royal College of Physicians of Edinburg, July 1995, Volume 25, Number 3, pages 421-424. The title of the article is : "The Management of Coronary Artery Disease : A Time for Reappraisal".