Dilemma of heart patients: Drug therapy or bypass surgery

There are hundreds, probably thousands of Filipinos with narrowing of the heart arteries called coronary artery disease, who are confronted with the dilemma of whether to undergo bypass surgery or not. Agreeing to a heart surgery is a most difficult decision they have to make. They may have various reasons ranging from financial to psychological factors. Hence, although theoretically, there may be some indication for bypass surgery, the physician finds himself in an equally difficult position to assess whether medical treatment may be optimized or not, instead of proceeding immediately with surgery.

In patients with established occlusion of the heart arteries, the physician should always consider the possibility of developed collateral circulation which is nature’s way to compensate, enabling the blood vessels to come to each other’s rescue. With adequate collateral circulation, small arteries arising from insignificantly occluded vessels may help maintain the blood flow to areas supposed to be supplied by the occluded arteries. In such cases, despite the occluded arteries, the patient’s chest discomfort does not increase in intensity, duration and frequency which would suggest a stable coronary artery disease.

In patients with coronary artery disease or CAD, a so-called therapeutic lifestyle change or TLC is imperative. Trying to identify and treat all modifiable risk factors such as high blood pressure, smoking, diabetes, elevated blood cholesterol, obesity, sedentary lifestyle and smoking can go a long way in alleviating their symptoms and improving their clinical outcome.

Medications

In addition to TLC, modern medicine now provides important medications which can help patients with CAD.

Aspirin can reduce platelet adhesiveness which is involved in blood clot formation. Platelet clumping can aggravate restricted circulation through the already narrowed blood vessels. Nitrates, either placed under the tongue (sublingual) during chest pains or taken as a regular medication, can relax narrowed blood vessels. Prolonged intake of nitrates can produce the so-called nitrate tolerance, leading to loss of efficacy of the nitrates.

To minimize this, other agents like vitamin C (ascorbic acid) or angiotensin converting enzyme inhibitors (ACEIs) such as perindopril (Coversyl) may be given. Some ACEIs have also been shown to prevent complications such as heart failure and improve survival in patients following a heart attack. A recent landmark trial, PROGRESS, has also shown that an ACEI (Coversyl) may also significantly prevent recurrent strokes even in those who do not have high blood pressure.

Betablockers such as metoprolol (Betaloc) are frequently given in patients with stable angina on the assumption that the chest pain is due to increased oxygen demand of the heart muscles. Betablockers can reduce oxygen demand by reducing contraction of the heart muscles. However, up to the present, there is no evidence that betablockers can prolong life in chronic stable angina. There is strong evidence though that it can improve survival in those who had suffered from a previous heart attack. It should not be given in patients with asthma, severe heart failure and coronary vessel spasm.

Cholesterol-lowering drugs

Lately, scientific evidence has been provided for the use of the cholesterol-lowering drugs, particularly the statins, in patients with coronary heart disease and even in those with average cholesterol levels. Statins have been shown to reduce cardiovascular events such as heart attack, stroke and deaths. The AVERT study reported that atorvastatin (Lipitor) showed the same benefit as balloon angioplasty, a procedure which dilates occluded arteries using a balloon-tipped catheter inserted through the groin.

Another important mechanism, which is not well-appreciated but should be properly addressed in patients with angina or chest pain, is cellular ischemia. Microvascular ischemia or a faulty circulation in the tiny blood vessels in the heart can aggravate occlusive problems in the bigger blood vessels. Position emission tomography (PET) scan is the current diagnostic method to assess cell function or viability and has been shown in some studies to detect ischemia much more accurately than angiography. Dobutamine stress test, done by infusing dobutamine to increase heart contraction and provoke coronary insufficiency, is another diagnostic test to establish microvascular ischemia.

Coronary reserve is adequate in 20 to 30 percent of patients with occluded blood vessels but with stable or silent ischemia without electrocardiographic (ECG) findings. Only eight percent may require intervention such as bypass surgery. A patient may show adequate coronary reserve based on laboratory tests such as a PET scan despite his occluded vessels. In such cases, drugs which work on the cellular level such as trimetazidine (Vastarel) may be given in addition to other medicines to improve the microvascular ischemia.

Surgical survival

The American College of Cardiology and American Heart Association guidelines on coronary artery bypass graft surgery show that after 10 years, surgical survival is only 5.7 months more compared to medical treatment. Furthermore, after five, 10 and 15 years, repeat surgery has to be performed in 25, 50 and 75 percent of cases, respectively. At present, there is no interventional producer that will prevent a future heart attack since a significantly occluded coronary vessel is usually stable. More importantly, a heart attack is due to the rupture of the rust-like atherosclerotic plaques in the arteries, leading to blood clots that can occlude even a non-significantly blocked coronary artery.

Thus, current knowledge and information indicate that surgical intervention has limited survival benefits, except in left main disease (blockage of the main left coronary artery) and in three-vessel disease (blockage of three arteries) with reduced heart function or failing hearts. Heart attack is not prevented by surgical intervention but is a risk during heart surgery. On the other hand, faster symptom relief, particularly of bothersome chest pains, can be achieved with bypass surgery among cases not responding well to drug treatment.

In conclusion, the ideal management of the heart patient is greatly dependent on the analysis of the case with assessment of all the risk factors and associated illnesses rather than a routine use of anti-angina agents or the straightforward recommendation of bypass surgery. After all, as physicians, our main goal is to prolong our patients’ lives and not only to fix rusty pipes.

(The author is a professor emeritus at the University of the Philippines College of Medicine, an academician of the National Academy of Science and Technology and a member of the scientific advisory board of CHARTER or Clinical Hypertension and Atherosclerosis Research on Therapies, Epidemiology and Risk Management. For feedback or inquiries, e-mail at [email protected].)