The Truth About Angiography
WHAT YOU SHOULD REALLY KNOW ABOUT CORONARY ANGIOGRAPHY
For almost 30 years, coronary angiography has been the diagnostic tool most revered by cardiovascular surgeons who invariably rely upon it for providing evidence for the need of surgery.
Coronary angiography (also called coronary arteriography) provides a filmed visualization of dye injected into the coronary arteries, 'supposedly' enabling skilled radiologists to pinpoint the location and precise (expressed in percentages) extent of blockages. However, radiological readings are rarely challenged. If the angiographer reports as much as a 75-percent occlusion of the so-called "time-bomb artery" (the left main and/or left anterior descending artery), the necessity for a bypass is considered confirmed.
Have patients gone to bypass surgery on the basis of misinterpreted coronary angiographies?
"Without question," according to Dr Arthur Selzer, cardiopulmonary lab chief at San Francisco's Presbyterian Hospital, who told a reporter he had "always been skeptical about angiographic readings, especially when expressed in percentages. That implies the evaluator is measuring something when he's just giving a visual impression of an obstruction.
It was not until the US National Heart, Lung and Blood Institute (NHLBI) undertook an investigation of angiogram reliability that cardiologists were given hard evidence that coronary angiography is more art than science.
The NHLBI report, presented at the 1979 American Heart Association meeting in Anaheim, California, revealed that inaccurate assessments of arteriograms are commonplace and that when experienced radiologists evaluate the same angiograms, they have conflicting opinions almost half the time.
The NHLBI conducted a three-pronged probe. In one study, three arteriographers, working independently, examined films of 28 patients who had died within 40 days of cardiac catheterizations. When their readings of the amount of occlusion of that all-important left main artery were compared with actual postmortem findings, it turned out they were more often wrong than right. In a whopping 82 per cent of their judgments, the degree of narrowing was significantly under or overestimated.
In the second stage of the research project, 30 films with distinct pathology were circulated among radiologists at three first-rate medical centers to discover how often first, second, and third opinions might agree. The discouraging results: only 61 percent of the time did two or more of the three groups reach the same conclusion.
Finally, in the third study, three months later, the same 30 films were recirculated to the same experienced radiologists, who did not know, of course, they were being asked to re-evaluate films they had seen before. This time, the radiologists not only disagreed with each other, they also disagreed with themselves! In 32 percent of the readings, their second evaluations differed from their first.
Exploding the myth of angiogram reliability had "profound implications for the diagnosis and treatment of coronary disease", declared Dr. Harvey G. Kemp, Jr., cardiology chief at St. Luke's Medical Center in New York, who had directed one segment of the research. Especially, he noted, since the evaluations had been conducted under the most favorable circumstances. "We had some of the best people reading the best quality angiograms available," he pointed out.
And how did the cardiovascular community respond to research that clearly indicated patients were being scheduled for bypass surgery based upon the results of erroneous diagnosis?
It did respond in no visible way! And nothing has changed in its practice!
Despite findings to the contrary, the coronary angiogram remains the "gold standard" of cardiovascular diagnosis and is still considered the final word when it comes to determining whether bypass surgery is indicated.
In 1982, an estimated 400,000 angiograms were performed all over the USA.
To refer to the angiogram, which costs about $2500 and usually requires a one- to five-day hospitalization, as a diagnostic test, is in itself misleading when, in fact, it is an operation to get the patient ready for another operation. The recommendation for bypass surgery is often a foregone conclusion.
Occluded arteries are to be expected. Remember, atherosclerotic plaque begins accumulating before the third decade of life, and many men and women who are symptom-free and considered healthy have been found to have 75- percent or more arterial blockage when autopsied after accidental death from causes unrelated to arterial disease.
Of all the diagnostic procedures, the angiogram is the one patients fear most.
"Worse than the surgery which followed," many report. It can be a long, uncomfortable procedure, involving catheterization through an artery in the arm or groin, which is guided up into the heart. Dye is then injected through the catheter directly into the patient's coronary arteries. X-ray films of the dye flow through blood vessels ostensibly show the location and pattern of blockages, but as we've already learned, error-ridden readings of those films degrade their diagnostic value.
How can doctors really precisely evaluate the arterial blockages on the angiograms in terms of percentages if they really can't see the cross-sections of the coronary arteries as the test provides only two-dimensional values? It is all a subjective opinion coming from the so-called experienced radiologist, angiographer or surgeon who eventually gives it out as an objective reality in order to convince the patient or his/her relatives to sign the agreement for coronary artery bypass surgery.
The best reason not to employ angiography as a routine testing tool is that it is relatively hazardous. Death rates from the procedure vary from 0.1 to 1.0 percent. It can also trigger a heart attack or stroke, either immediately or several months later, result in torn arteries, infection, or an allergic reaction to the dye used for contrasting the coronaries during angiography.
Finally, angiograms too often lead to a hazardous operation called bypass surgery. Once the cardiologist requests an angiogram, the patient is frequently on the final lap of the surgical track, not knowing how to avoid the bypass surgery or just not having enough time in the whole confusing situation to say NO to bypass surgery!
Elmer Cranton: BYPASSING BYPASS, Publisher Stein & Day, New York, 1984, pp. 151-154.
Angiography (an extract)
If your doctor suspects that something is awry, he may trot you off for angiography, an x-ray test supposed to examine the state of your arteries via a contrast dye. Nevertheless, there is plenty of evidence that this test also has a poor batting average, wrongfully setting in motion one of a number of potentially lethal heart operations. In one test in Boston, half of the 171 patients recommended to have a coronary angioplasty (the operation where furred-up veins are opened by tiny inflated balloons) on the basis of their angiograph were found not to need the operation. In the end, only 4 per cent of the patients advised to have the angiograph really needed one.16 Angiographs are also especially open to misinterpretation. In another study in which the pathology reports of deceased patients were compared with prior angiographs, two-thirds were found to be wrong.17
Lynne McTaggart: WHAT DOCTORS DON'T TELL YOU - the Truth About The Dangers Of Modern Medicine, Thorsons publishers, 1996, p. 23.