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One operation you may do better to bypass

MagazineApril 2004 (Vol. 15 Issue 1)One operation you may do better to bypass

Heart bypass - or coronary artery bypass graft (CABG) - is a radical procedure that has become the most frequently performed of all surgical operations, with around 500,000 carried out every year in the US alone

Heart bypass - or coronary artery bypass graft (CABG) - is a radical procedure that has become the most frequently performed of all surgical operations, with around 500,000 carried out every year in the US alone. Around 10 per cent of all heart patients will undergo a cardiac bypass, especially if they have one or more coronary arteries that are either blocked or severely narrowed.

In an operation that can last from two to six hours, the surgeon removes (or 'harvests') veins from the patient's leg, forearm or chest. These are then attached or grafted to a part of the artery that is not blocked, so bypassing the blocked section. Three or more bypasses may be created, depending on the number of blocked arteries.

The traditional approach is known as 'on-pump', where the heart is stopped for several hours to allow the surgeon to perform the graft. The patient is attached to a heart-lung machine, or pump, so that the blood supply can be diverted from the heart and sent through the pump, where it is oxygenated and then pumped back to the vital organs.

But a newer technique, which some surgeons believe is safer and less traumatic, is known as 'off-pump' or 'beating-heart bypass surgery'. While the grafting procedure for both approaches is the same, 'off-pump' is performed with a heart that continues to beat, stabilised by special equipment.

The 'off-pump' technique was developed as a response to the high risk of a serious adverse reaction, such as a stroke, heart attack or even death, following 'on-pump' surgery. A study from Yale University, for example, found that 27 per cent of 'on-pump' patients suffered a heart contraction after surgery (JAMA, 1996; 276: 300-6), while another study discovered that 6 per cent of patients suffer a stroke afterwards, 5 per cent of which are fatal; and half of the stroke victims suffer deterioration of their mental faculties (N Engl J Med, 1996; 335: 1857-63). A grimmer picture was painted by another study that found that 23 per cent of all CABG patients suffer some degree of mental decline after the operation (JAMA, 2002; 287: 1405-12).

However, mental health problems can occur with either procedure. This is because microscopic blood clots dislodged during surgery can then make their way to the brain (Stroke, 2000; 31: 707-13).

But considering it's such a new procedure, 'off-pump' is already raising concerns of its own. On the heels of several studies suggesting that the technique was safe, a new study among 102 patients at the Royal Brompton Hospital in London has found that grafts following 'off-pump' surgery are six times more likely to close up within three months compared with those inserted 'on-pump' (N Engl J Med, 2004; 350: 21-8).

The researchers suggest this may be down to the experience of the surgeons - and very few surgeons are likely to be highly competent in a technique that is so new. An 'off-pump' operation is a far more difficult procedure as the surgeon is working in a more restricted space and on a heart that is still beating.

What happens later on?
Most bypass studies have concentrated on problems that arise immediately after surgery, but what happens to the patient after he is allowed to go home? One analysis of 17,857 three-artery-bypass patients found that 590 of them - or 3.3 per cent - died within the first year after surgery. However, the rate dropped slightly - to 2.7 per cent - in patients who had two-vessel bypasses (J Am Coll Cardiol, 1999; 33: 63-72).

While these figures may seem low for a group of patients whose health has already been seriously compromised, they have to be weighed against the less than 1 per cent mortality rate among patients with similar blockages who were treated conservatively with medication, according to data collated by the Noninvasive Heart Center in San Diego, California (www.heartprotect.com/mortality-stats.shtml).

Not surprisingly, perhaps, the percentage of deaths rises with the age of the patient. In one study of 528 patients over 80 years of age, the 30-day mortality rate was 8.3 per cent, rising to 18 per cent after one year (Ann Thorac Surg, 1994; 58: 445-51).

Other common symptoms following surgery include breathing difficulties, bleeding, infection, depression, hypertension (high blood pressure) and arrhythmias (abnormal heart rhythms). Risk and adverse reactions increase in patients who are older, or have diabetes or other major health problems.

But if you do manage to successfully escape stroke, heart attack, mental problems or death itself, there's a reasonable chance that bypass surgery won't improve the health of your heart anyway. A meta-analysis of 37 studies found that heart function improved in only 37-55 per cent of all cases. The rest were neither better nor worse off than before surgery.

One symptom that bypass surgery is supposed to eradicate is recurring angina pectoris, usually caused by arterial blockage. But the same meta-analysis found that up to 20 per cent of bypass patients suffer chest pain even after surgery (J Am Coll Cardiol, 1997; 30: 1451-60).

The self-healing heart
It appears that bypass surgery interrupts a self-healing process that the body automatically initiates when it detects that not enough oxygen is reaching the heart. Extraordinarily, 75 per cent of heart patients experience a relief of pain within three to six months without any medical intervention because the body grows new blood vessels to form a natural bypass of the obstructed arteries.

These 'collateral vessels', as they are known, can be life-savers as they are able to keep the blood flowing to the heart even when a main artery has completely closed. These collaterals usually disappear after bypass surgery, as the body 'senses' a new flow of blood to the heart. But given the reasonable risk that the new grafted vessels may start closing within three months after surgery, the patient may well be left worse off than before.

Collateral vessels tend to grow when arterial narrowing and blocking take place slowly. A vessel that is only slightly narrowed, but which then suddenly blocks completely, is likely to cause a myocardial infarction (heart attack). The body can do nothing to prevent this.

'The common practice of rushing patients in for emergency or urgent surgery because of a severely narrowed coronary artery is completely unnecessary, and needlessly frightens the patient and his family,' says Dr Howard Wayne of the Noninvasive Heart Center.

This view is supported by a study that found that the chances of survival following a mild heart attack are higher if the hospital does not immediately operate, but adopts a conservative approach instead. Overall, 80 of 138 individuals who underwent invasive treatment, such as a bypass, died during a 23-month follow-up period, compared with 59 of 123 patients who had received conservative treatment, including drug therapy (N Engl J Med, 1998; 338: 1785-92).

A similar finding was made by the US Veterans' Administration VANQWISH trial, which tracked 920 patients who had suffered an acute heart attack. Around half had a bypass or other surgery while the rest were treated with conservative 'watchful waiting'. At the time of discharge from hospital, 21 patients who had undergone surgery had died, compared with just six who had been treated conservatively. After 30 months, 80 of the surgery patients had died whereas, in the 'watchful waiting' group, there were only 59 deaths (N Engl J Med, 1998; 338: 1785-92).

The self-healing mind
Even more remarkable than the self-healing body is the healing power of the mind, as researchers have discovered, albeit accidentally. They were endeavouring to determine the efficacy of a new heart procedure called 'direct myocardial revascularisation' (DMR), which uses a laser to create tiny holes in those portions of the heart that are not getting enough blood. The holes provide an alternative route for the blood to reach the heart.

Early trials had suggested that DMR was effective, and surgical DMR had been approved by the US medicines regulator, the Food and Drug Administration (FDA), and was being practised, with success, by cardiologists in operating theatres.

But DMR was stopped in its tracks by a major trial which found that it was no better than a placebo. The medical establishment overlooked the profound significance of this result. The trial proved that DMR worked - even for those patients who believed they had received DMR.

The DMR-treated patients reported a significant improvement in exercise capacity and angina symptoms six months after surgery - and the placebo group reported the same benefits, even though nothing had been done to them (Proceedings of the Transcatheter Cardiovascular Therapeutics Conference, 2000).

The power of the mind has also been underlined by another trial that discovered that those patients who prayed after bypass surgery recovered more quickly, and were also less likely to suffer from depression and social distress, common symptoms during the recovery period (J Alt Complement Med, 1997; 3: 343-53).

Who's for a bypass?
The appeal of the coronary bypass is based on research and findings made more than 20 years ago, when many of the reactions were not properly documented, and the appropriate patient was much younger than those today. Nowadays, cardiologists believe it is safe to operate on patients who are over 80.

'Best-practice' guidelines suggest that conservative management is the first option (J Myocard Ischemia, 1995; 5: 7-8; Ann Intern Med, 1997; 126: 551-3), but it's a message that, at best, is being observed by only a few cardiologists.

The popularity of bypasses differs dramatically between countries, and even between states in the US, with apparently no difference to the long-term health of heart patients. One study highlighted the enormous difference between patients with private health insurance in the US compared with similar patients in Canada who had no insurance. Over 10 per cent of the American patients had a bypass compared with just 1 per cent of the Canadians. In fact, over 60 per cent of the American patients received aggressive treatment, such as a bypass, angiography or angioplasty, compared with 9 per cent of the Canadians. Yet, after 30 days, the mortality rate among the Americans was 21.4 per cent vs 22.3 per cent among the Canadians; after one year, the rates were 34.3 and 34.4 per cent, respectively (N Engl J Med, 1997; 336: 1500-5).

But perhaps the essential issue is hidden within yet more statistics that suggest that a patient is likely to need another procedure to bypass the original bypass. Cardiologists recognise that grafted vessels will have closed within 10 years in 40 per cent of patients while other arteries will have closed in the remaining 60 per cent. This means that every bypass patient will need further surgery within a decade to either repair work already done or allow fresh work on different vessels.

It's not unusual for a patient to undergo a second or even third bypass operation. In fact, the chances of the necessity for a second operation increase by around 5 per cent every year.

While any cardiologist worth his wage packet will counsel the postoperative patient to change his lifestyle, improve his diet, start exercising and stop smoking, it's a message that is not being heard in a culture where there's always a quick-fix available.

But the quick-fix is not a safe one. The benefits of bypass surgery are unpredictable, and can bring on the very heart attack or stroke that it was supposed to prevent. It seems perverse that those who do nothing, or who control the problem with drugs or diet, can fare just as well, if not better, than those who have gone through the trauma of a procedure that involves cutting open the ribcage and stopping the heart for several hours.

As Dr Wayne says: 'If you must gamble, do so in Las Vegas, not on the operating table where you will bet everything you own on one roll of the dice.'

Bryan Hubbard


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