In one Canadian study of total cholesterol tests, nearly one-quarter were misclassified (as, say high risk), nearly a fifth registered a false-positive (a high cholesterol level when it wasn’t) and among those in the ‘high risk’ category, half had a false-positive reading.23
A few people in medicine are waking up to the fact that LDL levels alone are not an accurate predictor of heart disease. A large British Health Survey for England found that forecasting heart disease was far more accurate when factoring in the HDL levels, too.24
ECG Readings
Besides blood-pressure and cholesterol measurements, your doctor’s next favourite activity is listening to the state of your heartbeat. However, these days, the all-purpose stethoscope (never proved to have any advantages over the naked ear) has been replaced by a number of space-age gadgets, all designed to record the most minute changes in your heart’s ability to do its job.25 The stalwart of any cardiac specialist is the electrocardiogram (ECG), even though studies demonstrate enormous potential for error in recording or interpreting correct results. One study showed that computers, often used to interpret ECG readings, were only right two-thirds of the time, and missed 15 per cent of cases of enlargement of the right ventricle. Nevertheless, human beings didn’t fare much better; even trained heart specialists misinterpreted one out of every four readings.26 This is largely because, as with blood-pressure, readings can be affected as much as 20 per cent by recent activity, time of day, and even factors such as fear of the cardiologist’s findings! The late Dr Robert Mendelsohn wrote of a study in which electrocardiography detected only a quarter of proven cases of heart attack, and another study in which the tests found gross abnormalities in more than half of perfectly healthy people.27 As Stephen Fulder, author of How to Be a Healthy Patient (Hodder & Stoughton), notes, an incorrect ECG has led to ‘vague diagnoses of organic brain disease in healthy but unruly children, turning them into medical cases’.28
More state-of-the-art these days than the ECG is echo-cardiography – a diagnostic test on the heart, often using a mixture of contrast agents and soundwaves. The procedure had been gaining acceptance for its safety and accuracy. However, as with much ‘perfectly safe’ new technology, doctors have only recently realized that it is more dangerous than had been thought, possibly leading to life-and-death complications.
The first major study into the procedure discovered that it can be life-threatening in one in 210 cases, requiring special treatment or a stay in hospital; two people of the 3,000 studied suffered a heart attack after the procedure had been completed.29
The procedure often employs the use of microbubbles of a contrast agent like octafluoropropane, which are useful in visualizing the tiniest blood vessels of the heart. In laboratory research, rats have developed cardiac arrhythmias after being exposed to echocardiography because the contrast agent interacted with ultrasound, causing the alterations in heart rhythms. Although animal models often don’t apply to humans, this effect on a living being demonstrates that pulsed ultrasound can interact with bubbling contrast agents.30 There’s also evidence that the microbubbles cause destruction of capillaries, leaking red blood cells into skeletal muscle.31 Furthermore, the act of using pulse-sound waves with contrast agents in the brain has been shown to cause tissue damage to vascular walls, causing haemorrhage and tissue death.32
ANGIOGRAPHY
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. The doctor will place a catheter into a blood vessel in your arm or leg, guide it towards the heart, and inject what is usually an iodinated dye like isosorbide dinitrate, which then travels into the main pump of the heart. Once all this is in place, the doctor will then snap pictures of your heart from different angles, all the while replenishing the supply of dye.
There’s 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.33
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.34 A number of critics blame the test itself, which only examines the main coronary arteries, will not show any vessel smaller than a 0.5 mm in diameter and will only highlight, at best, a quarter of all the blood flowing to the heart.
Many patients with an abnormal angiogram are referred for surgery, when, at best, the procedure can locate the site of a block and its severity, but not overall heart function. Angiography, for instance, cannot distinguish between patients with stable and unstable angina.
There’s also a problem with accuracy. In one instance, after the deaths of three patients unsuccessfully treated by angioplasty, pathology reports found that the angiography on which the procedure was recommended had given misleading information about the patients’ conditions.35
Finally, this nasty little test is not without its own dangers. The procedure itself causes death in two of every 1,000 patients or, at very least, can trigger a heart attack, stroke or severe blood loss.
Serious side-effects occur, regardless of the type of dye used,36 and reactions to the dye often appear up to a week later. In one study, nearly half the patients involved complained of delayed reactions – including itchiness, rash and nausea – from one hour to seven days later.37 More than 5 per cent of patients suffer reactions to the dye of moderate intensity, particularly those who have had the test before,38 and one in ten will have a reaction of some sort. Although most are mild, at least 1 in every 2,500 is quite severe.39
If you have to have such a test, the less dangerous option may be magnetic-resonance-imaging angiography, which doesn’t require either x-rays or dyes, but a magnetic field and pulses of radiowave energy to produce pictures of soft body tissues.40 And as it provides pictures in three dimensions and on multiple planes, it shows better differentiation of tissues.
X-RAYS
X-rays are the most common procedure you’re likely to be exposed to at least once in your lifetime. Today they represent approximately 10 per cent of any Western nation’s health expenditure. Ionizing radiation is actually comprised of very high-frequency waves, which pass through living tissue. Depending on how dense the tissues are, the body retains some of this
