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Medical advances, while allowing more lives to be saved, have created more therapeutic dilemmas for doctors. The development of more therapeutic options for an increasingly elderly population with degenerative heart disease provide a real-world illustration.
Degenerative heart disease
One of the consequences of increasing longevity is an increase in the prevalence of degenerative heart disease. While degenerative disease affecting the heart artery is the most common cause of degenerative heart disease, degeneration of the heart valves is an increasing problem in the elderly. The valve that is most commonly affected is the aortic valve, which is situated between the left lower heart chamber and the aorta, the major blood vessel carrying oxygenated blood from the heart to the body; the main reason being that the aortic valve is the valve in the heart that is subjected to the highest pressure. With each heartbeat, the left lower heart chamber contracts and generates high pressure which pushes blood out of the left lower heart chamber across the open aortic valve into the aorta. When the left lower chamber starts to relax, the aortic valve will close to prevent blood from the aorta from flowing back into the heart.
'Wear and tear' of the valve
With the aortic valve opening and closing about 40 million times a year, it is not surprising that for those older than 75 years, more than one third have hardening and calcification of the aortic valve as a result of "wear and tear". In this elderly cohort, up to 9 per cent may develop severe narrowing of the aortic valve (aortic stenosis) as a result of degenerative processes.
Severe aortic stenosis is associated with an increased risk of death. However, some do remain relatively free of symptoms despite the presence of severe aortic stenosis and, for these people, the prognosis remains excellent with an expected death rate of less than one per cent per year.
Sudden death
The main concern in severe aortic stenosis is sudden death and of those who do die suddenly, only 4 per cent do not have any preceding symptoms.
Once symptoms arise as a result of severe aortic stenosis, the risk of death increases significantly from about 25 per cent at one year to 50 per cent at two years from the onset of symptoms. More than half of these deaths occur without warning.
On the average, the clock starts ticking with death occurring at five years for those with exertional chest discomfort, three years for those with fainting spells and two years for those with severe shortness of breath.
Treatment options
Given the high risk of death following the onset of symptoms, surgical replacement of the valve with a mechanical or biological valve has been the option of choice. However, aortic valve replacement surgery (AVRS) carries a risk of death of under 5 per cent even in those with no other significant medical problems. As many of these patients are elderly and have associated medical problems, the incidence of death, from all causes, at one year was about 27 per cent for those undergoing AVRS as reported in the PARTNER trial published in the New England Journal of Medicine in 2011.
Given the age of many of these patients and the presence of other medical conditions, other options have been developed. Over the last 10 years, new less invasive procedures have evolved which involve the implantation of an artificial biological valve across the existing narrowed aortic valve delivered through tubes inserted via arteries.
The PARTNER trial showed that the new technique - transcatheter aortic valve replacement (TAVR) - reduced death in those with severe aortic stenosis who were high-risk surgical candidates or considered inoperable when compared to non-surgical conventional therapy.
Another segment of the PARTNER trial compared TAVR with AVRS. The May 2012 edition of the New England Journal of Medicine reported that the two-year follow-up in the PARTNER trial supports TAVR as an alternative to AVRS in high-risk patients. Another TAVR system reported similar results in the ADVANCE trial in the Journal of the American College of Cardiology in 2012.
Currently, more than 50,000 of these devices have been implanted in patients throughout the world.
These developments mean that those with severe aortic stenosis have more options. Sub-analysis of the data from the TAVR trials showed that among these high-risk patients, those who have less concomitant medical conditions had high survival rates of about 96 per cent at six months.
Therapeutic dilemmas
While these developments in medical science should be lauded for providing more options, they also result in therapeutic dilemmas. In the past, those with symptomatic severe aortic stenosis had to choose between certain death or AVRS. As the TAVR trials involved the elderly who were considered high risk or inoperable, there is no data on whether relatively younger patients who were suitable for AVRS and yet refused surgery should be considered for TAVR.
Doctors face the dilemma of following guidelines strictly and allowing those who have rejected AVRS to choose the path of certain death or taking the moral high ground that when death is certain, potentially life-saving alternatives with favourable outcomes should be offered. The first option of allowing certain death will render the doctor blameless but the second option, which is a superior option to inaction, may potentially entangle the doctor in a web of blame should the outcome be adverse.
Medicine is as much an art as a science. Guidelines do not provide all the answers to the practice of medicine and where they are absent, wisdom, knowledge and experience will be the guiding lights for decision-making. The greatest challenge of medicine in future is not the provision of new solutions for old problems but whether, in a rapidly changing world, doctors will prefer the safe, blameless approach or step out and make difficult decisions in the best interest of patients. Whether most doctors choose the "blameless path" or the "moral path" will be very much shaped by how their actions are viewed in the face of an adverse outcome. Doctors can save lives, but not every life can be saved.
The writer is medical director at the Singapore Heart, Stroke & Cancer Centre. He is also editor-in-chief, Heart Asia (a journal of the British Medical Journal Publishing Group); chairman, scientific advisory board, Asia Pacific Heart Association; and honorary professor and senior medical adviser, Peking University Heart Centre.
This article was first published in The Business Times.