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TO DO IT OR NOT DO??
Shekhar Ambardekar
Cardiologist, Sadanand Danait Hospital, SL Raheja Hospital.
Coronary interventions have made a great impact on the management of all subsets of coronary arterial disease viz. stable angina pectoris, unstable angina pectoris, non-Q wave myocardial infarction and Q wave myocardial infarctions. More and more centres have now acquired this facility especially in cities like Mumbai and more and more patients of this disease are now subjected to coronary interventions. Patients and their close relatives are now familiar with terms like angiography, angioplasty, stents and bypass surgery. Many of them expect the treating doctor to recommend these procedures after the diagnosis of "ischaemic heart disease" is made.
It is important however to know what impact these interventions have made on the outcome. It is logical to expect favourable results in terms of morbidity and mortality by increasing blood flow to ischaemic zones since the basis for ischaemia is obstructed coronary arteries. But is it scientifically proven? What has the clinical experience to say?
With wider use of the coronary interventions all over the world a lot of data is now available looking at the results of these procedures more critically. They have compared the invasive approach to more conventional medical therapy in all subsets of ischaemic heart disease and observations should prove to be eyeopeners.
Coronary angioplasties and bypass surgeries are recommended on the basis of anatomical lesions in the coronaries. Various studies in pathophysiology of ischaemic heart disease have brought to light important facts. Most of the acute coronary events like acute myocardial infarction and sudden death occur due to atherosclerotic plaques which are small but rich in lipid core. They are angiographically unimpressive and not considered indications for interventions. Angiographically obstructive lesions are mainly responsible for stable angina pectoris and rarely cause acute coronary events. [1] Treatment of these lesions by bypass surgery or balloon angioplasty therefore cannot be expected to have impact on rate of myocardial infarction and mortality. This is aptly shown by the well known RITA-2 trial. [2] In fact over 2-7 years, this study showed higher rate of death or myocardial infarction with coronary angioplasty (6.3%) than with medical therapy (3.3%). Patients assigned to angioplasty group also required bypass surgery more frequently than those put on medical therapy.
Another long term follow up study after initial success of angioplasty showed3 that over 10 years 35% patients required repeat coronary angioplsty, 31% required bypass surgery, 14% had acute myocardial infarction and 19% died. Of the remaining, 53% had persistent or recurrent angina. Similar studies on bypass surgery also caution us on the long term results of the surgical approach. In a 10 year follow up study of 1388 CABG patients, only 18% of grafts were patent. [4] Use of invasive approach in acute myocardial infarction is theoretically attractive and useful in some however routine use of this modality of treatment does not seem appropriate. Recently published [5] (VANQWISH) study looked at patients of non-Q myocardial infarction treated invasively and compared the outcome with those treated conservatively. Patients assigned to the invasive strategy had worse clinical outcomes during the first year of follow up. Non fatal myocardial infarctions and death were both significantly higher at hospital discharge, one month and one year in the invasive group when compared to the conservatively treated group. Subsequent follow up showed no further difference in the two groups.
Many small studies recommend PAMI (primary angioplasty in myocardial infarction), however a large study (1050 patients treated with angioplasty vs. 2095 patients treated with thrombolytic therapy) showed no benefit of any significance during hospitalisation as well as long term follow up with invasive approach. [6] It is found that all over the world, the strategies in managing unstable angina pectoris or suspected myocardial infarctions vary from country to country. Use of invasive procedures is maximum in Brazil and USA, intermediate in Canada and Australia and lowest in Hungary and Poland. [7] However there is no difference in rate of cardiovascular deaths or myocardial infarctions. Even in USA itself there is regional variation in the use of invasive procedures in management of acute myocardial infarction without any difference in the clinical outcome between patients treated invasively and those treated conservatively. [8] Conclusion of such studies indicates that use of invasive approach is directed mainly by the wider availability of the facilities for invasive treatment rather than difference in clinical indications.
Even in our country, though there are not many studies to compare the results of the different treatment modalities, common observation does not indicate any improvement in morbidity and mortality from ischaemic heart disease in big cities like Mumbai, Delhi, etc. when compared to other towns where facilities for invasive treatment are not available. The difference in the strategies also stem up because in the present era of high technology, patients, their family members and some doctors expect and insist on aggressive therapy. The term "conservative management" may project the impression (to physicians and patients alike) of obsolescence, inadequacy and inferiority rather than of thoughtful reflection and the application of scientifically based, ischaemia guided therapy. [9]
It must be remembered that over last 25 years mortality by coronary artery disease in the USA is reduced by 50%. This is attributed to aggressive modification of lifestyle by the entire population rather than to high-tech hospital care of individual cardiac patients. [10]
On this background, invasive procedures like balloon angioplasty and coronary bypass grafting which are extremely useful when employed for proper indications will continue to give good results in selected individuals. Patients having intractable pain not controlled by medical therapy, patients having compromised LV function will continue to derive benefits from the invasive approach. Significant left main disease, severe triple vessel disease - especially with poor LV function should still be subjected to bypass surgery. We should encourage revascularisation based on the patient’s symptoms and disability rather than on ‘menacing angiograms’. [11]REFERENCES
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