Low Diagnostic Coronary Angiography Yields: Perhaps we need a higher threshold to perform

Low Diagnostic Coronary Angiography Yields:

Perhaps we need a higher threshold to perform

Dr David KL Quek, FNHAM, FACC (Published NHAM Pulse, April 2010, pg2)

A recent research paper by the Duke Clinical Research Institute (Patel MR, et al. Low Diagnostic Yield of Elective Coronary Angiography. N Engl J Med 2010;362:886-95.) should prod every cardiologist to review his or her threshold in the performance of ‘routine’ coronary angiography for the diagnosis of significant coronary artery disease.  


This concept to justify clinical performance processes to help check potentially over-used procedures and testing has now become more and more crucial in the era of evidence-based medical practice and health costs constraints.

More importantly on a practical basis, we are exhorted to contribute more actively towards checking escalating health care cost by becoming more thoughtful and judicious in our clinical decision-making.

Justifiable Diagnostic Screening still Unresolved

In the USA, some USD14.1 billion is spent on imaging diagnostic testing annually by Medicare alone. More and more are now spent on early diagnostic procedures in the hope of detecting and treating potentially lethal coronary artery disease, but which seems to elude the very best of our diagnostic efforts and risk stratifying strategies.

Cardiologists have an unenviable position with regards to the heightened awareness of risks of coronary artery disease, among the general public globally.

Because of the huge success of our diagnostic and therapeutic capabilities, and the very many high profile celebrities surviving or even dying from heart attacks, widespread health promotional education has enlightened the public as never before.

It would be true to say that nearly every one has heard of the dangers of heart attacks and perhaps too all the major risk 
factors. Thus, it is not difficult to envisage that whenever any one person feels some twinges in the chest or suspect that he or she might be suffering a heart ailment, many present themselves to physicians for clarification and testing, and perhaps especially for reassurance that all is well, or otherwise.

Hence, there is a rising demand for health screening testing including exclusion of significant heart disease.

Unfortunately, even as we get more sophisticated, we do know that the diagnostic yield of most health screening tests for significant heart disease is disappointingly low. From simple risk factor assessments and stratification, stress ECG, stress echocardiograms to even calcium scoring to MSCT-angiogram, we are still only finding tiny incremental yields to help us not miss potentially lethal heart disease or sudden death.

Perhaps, this is the result of greater unrealistic expectations from both patients and physicians alike. We have become more enamoured by our abilities to reduce the scourge of heart disease, so much so, that we are continuously looking for the Holy Grail at preventing earlier and earlier unstable plaques, which can trigger sudden loss of life. Some harbour hopes of totally eradicating coronary artery disease itself!

A few years ago, a group of eminent cardiologists in their enthusiasm to advocate earlier detection of heart disease, pushed for a public health program to screen more aggressively for heart disease and unstable plaques, the MDCT was the touted approach then for mass screening. However, this was not universally adopted when clearer views of such a program were scrutinized. The less than consistent detection rates, resolution discrepancies, artifacts, radiation risks of mass screening with CT angiogram has stalled the more widespread use of this modality.

Then, there have been others, (cardiologists, both academic and private sector) who have swung even farther to the right of ‘gold-standardising’ diagnosis with routine coronary angiography, on demand even to detect or to exclude significant coronary stenosis. They persuade their patients that this is the only sure way of not missing anything to do with their heart, except that this is disingenuous: there is no guarantee that a heart attack would not occur in the future!

This approach is clearly unacceptable and when used as a casual screening tool, almost universally regarded as Class III indication, or worse that which may cause harm. Risks of tachyarrhythmias, embolic phenomena, CVAs, renal impairment or even untoward unexpected bleeding, while very low, are not zero. The latest analysis of the ACC National Cardiovascular registry database therefore lends weight to the fact that indiscriminate testing with unnecessary coronary angiography has low yields, which cannot be justified!

The American College of Cardiology National Cardiovascular Data Registry (NCDR) Results:

Of the nearly 2 million coronary angiographies performed in the NCDR database, some 60.3% had significant obstructive CAD (Obstructive coronary artery disease was defined as stenosis of 50% or more of the diameter of the

left main coronary artery or stenosis of 70% or more of the diameter of a major epicardial or branch vessel that was more than 2.0 mm diameter. When sensitivity was broadened to any stenosis of 50% or more for any coronary vessel, this increased diagnostic yield results by some 4%.)

When acute coronary syndromes, cardiogenic shock, proven past CAD, past histories of revascularisation procedures, and other defined indications were excluded, some 397,954 were eligible for analysis. Of these, the yields are as shown in the figure below:

Noninvasive testing (resting electrocardiography, echocardiography, computed tomography [CT], or a stress test) was performed in 83.9% of the patients before invasive angiography, of which 68.6% had a positive test result. Patients with a positive noninvasive test result had higher rate of obstructive coronary artery disease than those who did not, before angiography (41.0% vs. 35.0%, P<0.001); the rate of obstructive CAD among patients with a positive test result was also higher than the rate among those with equivocal or negative test results (41.3%, vs. 27.1% and 28.3%, respectively).

Since the data set included asymptomatic and symptomatic patients, the association between rates of obstructive coronary artery disease and the results of noninvasive tests are presented in Figure 2 according to Framingham risk-score categories (low, intermediate, or high) and symptom categories (no symptoms, atypical symptoms, or angina). The diagnostic yield for obstructive coronary artery disease increased with a higher Framingham risk score, as well as with the presence of angina 
(P<0.001 for both analyses).

 

Figure 3 below shows the model’s predictive ability when symptom characteristics, i.e. beyond Framingham risk scores alone were analysed. However, stratifying Framingham risk levels, with positive, equivocal or negative noninvasive test was associated with very small incremental yields for presence of obstructive coronary artery disease (C-statistic, 0.764; 95% CI, 0.762 to 0.765), for all three Framingham risk levels.

It appears that less than 4 in 10 among those undergoing invasive coronary angiography (37.6%) had obstructive CAD (i.e., ≥50% stenosis of the left main coronary artery or ≥70% stenosis of a major epicardial vessel). The percentage was similar (41.0%) when the definition of obstructive disease was expanded to include stenosis of 50% or more of any coronary vessel.

Thus, although certain demographic and clinical characteristics could be useful in determining the likelihood that obstructive coronary artery disease would be present, the incremental value of a positive result on a noninvasive test (including any of a broad range of tests such as resting electrocardiography, echocardiography, CT, or stress test) was limited.

This begs the question whether such diagnostic tests should be promoted in a systematic way. Of course, this does not mean that those with clear indications should not be referred for such testing, if not for therapeutic options, then for risk stratification strategies and management.

But, this poses challenges for cardiologists and physicians who should be very clear in discussing with their patients the realistic clinical utility of non-invasive testing and especially for coronary angiography. For those with not much or typical symptoms, then most of these tests may not serve to enlighten either the doctor or the patient as to his or her status of cardiac health!

So, What should Cardiologists Do?

In Malaysia, we do have an unhealthy love affair with all that is new and fashionable, especially technology-driven equipment and techniques. These are touted as must-have amenities bordering on questionable competition for who has the newest, most advanced equipment. There are about 20 ultra-fast multi-detector CT scanners in the Klang valley; and another 15 or so cardiac catheterisation laboratories as well.

Business people in collaboration with physicians, usually fund such huge capital-intensive enterprises, which then demand quick returns on their investments. Thus, there is an unspoken nudge toward greater utilization of such facilities to help justify their purchases. To compound the problem, it is not inconceivable that cardiologists are also venally encouraged to use more of these testing modalities, because they would personally benefit from procedure fees—the sort of asymmetrical moral hazard, which has been decried by many health economists.

In several reports now, a few cardiologists in the USA have been charged and indicted for fraud for performing un-indicated coronary angiography, and even unnecessary angioplasties. Linked hospitals have also been fined huge sums for condoning over-utilisation of such procedures without sufficient oversight or appropriate audit.

With the NCDR data in mind we should now seriously reconsider our penchant for early invasive testing, and resort to better evidence-based medicine to offer our patients the optimum care without fear of under-diagnosing or missing non-critical disease, which are usually not life-threatening (this is not addressed in this analysis). But we do have past precedents, the COURAGE study had shown quite conclusively that when given optimal medical therapy, even significant but stable coronary artery disease can be managed quite well, with no increase in mortality or major adverse complications.

Let’s give more thought as to how we practice cardiovascular medicine and remind ourselves that the best medicine is one that is evidence-based and purely for the patient’s benefit, not ours or our personal financial gain per se.

We have to learn to stay our reflexive tendency to diagnostic or therapeutic procedures which may not improve risk assessment or clinical management for our patients, but which may instead increase their potential harms and incur unnecessary costs.

Unless we rein in our free-for-all approach, the escalation in costs may actually impose external oversight and imposition of audits and cost-constraints for reimbursements, through case-mix or DRG models.

Worse, callous over-utilisation of procedures including coronary angiography may demean the trust and esteem which the public has for the physician, the cardiologist, and impeach our much-vaunted medical professionalism!

Medicine—Reigniting our Passion…

Medicine—Reigniting our Passion…

Dr David KL Quek, drquek@gmail.com

“Where is the wisdom we have lost in knowledge?

Where is the knowledge we have lost in information?”

~ T.S. Eliot. The Rock, 1934

“Physicians combine two diverse tendencies in their daily functioning, a scientific mode of thinking and a clinical commitment to healing. The former requires us to be rigorous, dispassionate, objective, loath to reach conclusions until incontrovertible facts have been assembled. The clinical, or professional, component, on the other hand, compelled by the urgency to assuage suffering and to defend life, demands immediate action even in the absence of complete data." ~ Bernard Lown, M.D. in Prescription for Survival: A Doctor’s Journey to end Nuclear Madness. Berrett-Koehler Publishers, Inc., San Francisco, 2008, p.61.

Traditional roots of medicine demand some personal reflection…

Some thirty years of practising as a doctor can certainly embolden one to try and reflect upon a profession that so intimately inhabits one’s personal universe. Nevertheless, I do so with trepidation that I may have overstepped my expertise, my uncertain moral position in the august footsteps of so many unmatchable giants of our medical profession.

Yet, I have been impelled to do so, to try and set down my nebulous thoughts as to what and how the concept of the modern doctor is changing or taking shape, amidst the tremendous transformations and challenges that have swept the medical profession and health care scene.

Being a medical doctor is certainly one profession, which can become an all-consuming life and living itself—one learns to eat, drink, and breathe medicine.

Our thoughts and thought processes are submerged within the lingering echoes and ethos of a Hippocratic ancien regime: one of highly-structured codified dos and don’ts and exhortations of an intricately-crafted analytical process. Many are now lamenting the relevance of these methods and constraints, the seemingly outmoded sweeping codes, so enshrined within its antiquarian Aesculapian confines.

Nevertheless this singular system has continually defined and redefined itself, with modernizing inputs from our forefathers—all highly regarded stalwart champions of principled medical practices and professionalism. On the basis of the Hippocratic tradition, medical practice has been transformed increasingly into a more rigorous scientific system—one that is better evidence-based, with consistent veridical facts, and most importantly, one that is able to deliver reliable repeatable quality of care and cure outcomes.

No longer is the practice of medicine simply the handed down legacies of trusted wisdom and opinions of a few experienced if authoritative masters. Direct challenges to untested even if persistently accepted practices from long ago have helped democratize and expand the scientific reach of medicine into more solid bases of substantiation.

Science and art meld together in an intertwined universe of shifting and ratifying complexities, which ultimately give up its ghost in some form of a therapeutic modus operandi. At least, that is what appears to be the articulated goal of medicine—to comfort always, to heal sometimes, and hopefully never to cause harm: Primum non Nocere (First, do no harm).

Most importantly but often forgotten in the glitzy or fevered attempts at dealing with modern ailments and newly-medicalized disorders, we should remember that our patients are our raison d’étre. Medicine exists because there are patients out there who need or deserve our services, our care. The converse is not necessarily true, and may indeed not be to our patients’ benefit.

These days, it is possible to forget that oftentimes, tangential rather than exceptional discoveries create new demands for newer approaches which may have become too all-inclusive: our healthcare lattice is thrown far too wide and spread too thinly. So much so that lifestyle, ageing-related or other psychosocial aberrations have become incorporated within new designations as novel ailments.

Some have suggested that such ready ‘medicalisation’ may be too indiscriminate and inappropriate. Some have been promoted and perhaps may even have been invented by “Big Pharma”. Some of these disorders have become propagandized and marketed as “real” ailments, which need to be diagnosed, investigated, and yes, even treated aggressively.

Evolving evidence-based Medicine

From folkloric herbs, bone setting, stone cutting, etc. we have now entered into a new era of thrust for evidence-based medical practice, or at least that’s what has been loudly proclaimed of late.

Out of the ashes of historical anecdotes and passing down of learned experiences, accepted ‘truths’ have been systematically debunked when put to more rigorous testing and ratification. Many pearls of long-accepted wisdom have been crushed under the weight of new evidence, and in their places have arisen newer concepts of better-tested, better proven ideas. However, the reality is that medical practice is not all based on rigorous or dogmatic scientific facts. We still have so many incomplete answers or limited comprehension on countless ailments.

Complicating this is the fact that different ailments affect different patients differently: some more gently, while others more catastrophically and perhaps even fatally. Such is the inconsistency of occurrences which doctors have labelled as ‘idiosyncrasies’, i.e. chance events and effects, which affect individual patients in peculiar, unexpected and often inexplicable ways.

Unbeknownst to some of our frustrated patients out there (who wonder why we sometimes cannot be more definite or sure, or why some unexpected outcomes or complications continue to take place), doctors still don’t know quite enough, at least, not for each and every medical illness or variant. We still puzzle over why certain twists and turns occur despite the rigorous implementation of what’s considered proper treatment, which are guided by evidence and research. The human body still escapes total understanding and occasionally behaves erratically and outside the rigid boundaries of expectation.

Even the most brilliantly gifted or polymath amongst us, would shy away from presuming that they know everything. However, there are those who do perceive of themselves as ‘gods’, the know-all who can dispense largesse and treat without any qualms of uncertainty but with the dogmatic conviction of a cocksure pedant—the expert extraordinaire. But with the relentless onslaught of scientific evidence constantly permeating the information universe, it would certainly be foolhardy to be so presumptuous, leaving far too little for cautious error or acknowledgement of possible uncertainties.

Medicine’s self-correcting mechanisms may be slow, erratic and staggered…

By espousing a self-correcting mechanism based on scientific tenets, western-style allopathic medicine has been marching along relentlessly, almost always improving upon itself, whilst dumping wrong or inaccurate concepts, measures, or treatment modalities. Sometimes a long-discarded or long-forgotten concept is revitalized and rejuvenated as more discoveries prove its better consistency and veracity.

This flip-flopping of ideas and beliefs can be confusing to the layperson, who wonders why if medicine is a science, there is this shifting or changing of premises. How can some medical ‘facts’ suddenly be overthrown tomorrow by some newer discoveries, or newer ‘truths’? How can a drug, long prescribed for a certain indication, be suddenly hazardous for another condition, so that it has to be withdrawn?

This is especially so when news-breaking clinical studies show adverse outcomes much to the consternation and confusion of the research scientists who had predicted otherwise.

Just a few years ago, an arthritis pain-relieving drug Vioxx (refocoxib) was found to be associated with increased heart attack and stroke rates especially after prolonged use, and had to be withdrawn. But this later action was reluctantly foisted upon the company only after costly legal battles; Vioxx had earlier been approved for global use for several years. Thus, while Vioxx was very good at its narrowly-defined efficacy, it was unfortunately putting more people at risk of suffering and succumbing to seemingly unrelated cardiovascular disease. This covert but delayed safety issue was regrettably not uncovered soon enough, but was clearly not acceptable for treatment of non-life-threatening chronic disorders when there are safer alternatives available.

Another example relates to some changed surgical decision pathways. Why indeed have some long-established surgeries now been deemed unneeded, outdated and even passé? Yet at other times why have drastic, occasionally mutilating, surgeries to be emergently performed to save a tenuous life?

Gastric surgery comes to mind as a glaring example, when aggressive antibiotic-acid reduction medications have supplanted gastric resection for ulcer disease. A previously well-hidden bacterium (helicobacter pylori) is now established as the cause of most of stomach ulcers and even cancers. Yet, conversely some life-saving gastrectomies might still be necessary in severely bleeding and exsanguinating gastritis, when medical therapy fails.

Another controversial if more personally-decided surgery is that regarding the option for radical mastectomy or simple lumpectomy for breast cancer. Questions of staging and lymph gland involvement are not readily clear for many patients, who frequently opt for less mutilating if incomplete surgery. Then, there’s that question of whether every patient should have that expensive not-readily available PET-CT scan to determine if the cancer had spread beyond its usual boundaries…

The choice for complex angioplasties versus coronary bypass surgery for multi-vessel coronary artery disease is another point of contention, which sometimes border on personal patient-physician preference rather than hard scientific evidence. Such evidence bases unfortunately fluctuate in time-dependent verifiable specifics, which are sometimes dictated by contemporary changes or refinements in technique or device advances.

Thus, are there really any unfailing medical ‘truths’ out there? Perhaps there never will be. This is because modern medicine is often about evolving comprehension and continual scientific ratification of concepts and practices. Some of these may indeed be revolutionary and requiring paradigmatic change in mindset and orientation.

Best Fit Medicine ever changing, updating…

Modern medicine these days is constantly adopting what’s currently the best fit, the most appropriately cohesive model, to the best of our up-to-date understanding, as we dip our curious minds into the flowing river of advances and new knowledge. We can never really dip into the same river twice without its nourishing waters having moved along… but it is through this ever-changing experience that we can hope to harness the best that modern medical knowledge can offer.

Thus, we really cannot afford to simply sit back and be idly complacent while the inexorable advances of medical and scientific research and discoveries unravel with such accelerating paces—we have to update our knowledge base and skills all the time—hopefully on a lifelong journey of continuing professional development (previously known as continuing medical education), so clichéd, yet so much a desired mandate for today’s physicians.

The Internet, the World Wide Web and the explosive information expansion has not helped alleviate this dilemma of how to make practical sense of what’s good and what works. Because, for each of our individual patients—ultimately and in a very curiously uneconomic way—being a doctor usually means dealing with that one patient and his/her problem, piecemeal.

[Only in epidemics or potentially public health calamities e.g. avian influenza or SARS (severe acute respiratory syndrome) and the current A(H1N1) pandemic, do we engage our autocratic prerogative, which collectively and without exception, corral our resources and authorise therapeutic or prophylactic measures on a designated at risk or exposed population.]

Medicine can and does consume our souls if we let it, and it can and probably should dictate a mystical ethical code of conduct which should exhort us to rise way above all others, in our dealings with humanity and with our patients in particular.

“Deprofessionalization”

However, these days, in some areas, the practice of medicine appears to have been lost in translation. Many doctors are disenchanted with the so-called practice as usual—many are now feeling a greater and greater sense of loss of autonomy and a growing sense of ‘deprofessionalization’, where insurers, third party payers, and managed care organisations are dictating how they practice, who they can treat and when, and how much can be reimbursed or not at all.

In 2006, the roll-out of the private healthcare facilities and services regulations for Malaysian doctors, added more fuel to the firestorm of practice issues which seem to overwhelm the wretched medical practitioner!

So what do some doctors do? They have become angry and feel quite betrayed. Practising clinical medicine had become a grinding drudge for some: mounting paper-work, senseless work-flow charts and reports, with ‘ludicrous’ micromanaging oversights, which seem excessive and demoralizing. Many had described these harsh regulatory articles and especially the prescribed punishments as criminalizing and degrading.

Such laws seem to imply that doctors who had been practising autonomously all along with little intrusion or mishaps, have become potential felons (in one fell swoop of the enactment of the Regulations by the Minister of Health) and that if some of these practice issues are not modified or adhered to, they are to be regarded as criminals with stiff fines and even jail time! Some had indignantly expressed their intentions to quit practising medicine altogether, others are defiantly recalcitrant.

Some doctors have become so unhappy, angst-driven and frustrated that they have lost their zeal and passion for their medical practice—the former patient-doctor relationship have become sundered with suspicion and regulatory mess-up, which trespass into their sense of justice and professionalism.

Dabbling in Fringe Therapies…

Quite a number of the more enterprising have moved laterally to fringe margins of allied health disciplines. Dabbling or even full-time engagement with beauty or aesthetic health care appears simpler, i.e. away from the more demanding and challenging clinical practice of general or family practice.

Some also have moved into the even more lucrative anti-ageing or drug-dependency programmes, which once again seem to be more rewarding and satisfying, even if less taxing mentally or intellectually!

Others indulge in fringe, obscure if esoteric “techno-babble” pseudo-medical practices (e.g. electro-diagnostic analysis for general health promotion, live blood analysis as screening procedure for possible medical ailments, whole body aura analysis, colonic washout therapy, qi gong for all ailments, ozone therapy, chelation therapy, etc.) which creates a semblance of ‘scientism’ and rational modernity, but which are at best hocus-pocus quackery at its most sophisticated.

Some are embracing complementary alternative medicine, which appears to be increasingly popular and in sync with the more suggestible public out there, despite the fact that their scientific bases are so much less proved, or none at all.

Erosion of youthful dreams, reigniting compassion and vocation…

When as a young teenager I dreamt of becoming a doctor, my fledgling youthful hopes and ambitions now seem so wonderfully fervid and overpowering. Back then, the starry-eyed passion and awe seamlessly suffused through my senses and waking moments and enveloped my entire psyche and persona. Then too, my concept of altruistic high-mindedness appeared to overwhelm all other considerations.

How far-away these thoughts and feelings now sometimes appear, how nebulous, how child-like and oh, how evanescent… That naïveté, which I have so blurry-eyed conceptualised, now seems so distant a memory, sometimes… Hard-nosed reality these days shatters our childlike dreams of simplicity, equanimity.

It is against this backdrop, that we should address the issue of where our medical profession is heading. With the onslaught of rising commercialism, market-driven personal consumerism, and greater patient autonomy, it is becoming increasingly hard for the medical professional to practice as a doctor.

To be that quintessential compassionate, empathetic health care provider so to speak, can be extremely demanding and challenging, what with the inherent diagnostic/therapeutic uncertainties, the spectre of fees and costs, medico-legal and other pecuniary considerations impinging upon the doctor’s and the patient’s consciousness.

During the coming two years of my presidency I wish to address some of these issues through the prism of a physician who passionately believes that medical doctors can make a difference, that health care can and must be engaged to make it as human and humane as possible, while staving off the onslaughts of rising commercialism, medicalisation, political and/or third-party oversight and progressive loss of our physician autonomy.

I hope to inspire a new look into the possible art of healing which appears to have taken a backseat with the rising tide of challenges and the onslaught of de-motivating practice issues. We must learn to reclaim our sense of purpose, our vocational goal, and reassert our meaningful role in modern society.