January Meeting, Riverview

While we were eating our heart-healthy wraps, salad and fruit salad, Sheila Turkel introduced our first speaker, CT scanner supervisor Richard Zara, who had a personal story connected with his work.

First Rich told us the software for the scanner at Riverview was recently updated to minimize the radiation exposure. His own story was that he had trouble reading and last August his eye doctor said he needed cataract surgery. Preoperative testing showed that his cholesterol was high and a CAT scan was scheduled. The CAT scan revealed a large aortic aneurysm. He went straight to Jersey Shore for surgery, where he met some reassuring visitors from our Mended Hearts chapter. He credits the scanner for saving his life, and Mended Hearts for helping him through the experience. The cataract surgery is yet to be done.

One of the tests done with the scanner is a “calcium score” screening test for coronary artery disease. No prescription is needed but insurance doesn’t always cover it; the cost to the patient is $250. Other scans require a prescription from a doctor, not necessarily a cardiologist.

Our main speaker was Dr. Dale Edlin, a cardiologist, who told us a lot more about cardiac CT scanning. It can be used for screening to see if there’s any problem, for risk assessment as a guide to treatment, or for identifying the cause of a patient’s symptoms.

About half of all heart attacks occur in patients with no history of heart disease; about one third of these first heart attacks are fatal. Screening would have helped these patients.

Screening for heart disease risk is ordinarily based on risk factors: age, sex, blood pressure, diabetes, tobacco use, gout, family history, cholesterol. Based on risk factors, about 35 percent are “low” risk, 40 percent are “intermediate” risk, and 25 percent are “high” risk.

As plaque develops in an artery, first little fatty streaks appear, then plaque starts to build up inside it. At first the artery gets bigger, so the lumen, the space inside, is about the same size. There’s no narrowing, but the plaque could rupture and block the artery, causing a heart attack.

The plaque also develops little bits of calcium in it. A CAT scan without any contrast dye can show the calcifications and you can get a number called a calcium score. This is a screening test. It doesn’t detect blockages; it detects plaque. It’s a very powerful indicator of how likely a patient is to have a heart attack. If you’ve already had a heart attack or other cardiac event this is not for you. We already know you have heart disease.

When patients who have already been screened based on risk factors are given calcium score screening, about 2 percent of low risk patients are reclassified to higher risk, and 16 percent of high risk patients are reclassified to lower risk, but 53 percent of intermediate risk patients are reclassified to low or high risk. So calcium score screening is most useful for intermediate risk patients.

CT scanning can also be done with injection of a contrast dye that blocks X-rays, and here the scan can detect blockages like a catheterization. It shows the inside of each artery, the lumen, and where the image of the lumen is interrupted or narrowed, there you have a blockage. It’s better than catheterization to identify abnormal heart and artery structures.

CT scanning is exciting because it’s fairly new and still developing, it’s non-invasive, it’s almost harmless (the patient does get X-ray dye), it’s very accurate, it’s diagnostic in most cases, it’s fairly simple, and it’s almost “healthy” (patients are exposed to radiation). It started with single slice machines, then multislice, now 64 slices in Riverview, more slices and multi-detector systems in development.

The technique involves a single breath-hold for about 10 seconds, the more slices the quicker. Contrast medium is injected in the arm to reach the heart quickly, and the patient needs good kidney function to get rid of it. The radiation dose is about ten times as much as a cardiac catheterization. The patient may need a beta blocker to get the heart rate below 60 bpm so the computer can track the heart beat to get pictures between beats.

Limitations of the technique are that allergies or kidney disease may limit the use of contrast medium, heart rate must be slow and regular, stents (or lots of calcium) are hard to see through, breath must be held, radiation dose should be limited.

Strengths are that it’s a proven screening technique, it’s quick and easy, very accurate, unlikely to miss patients with heart disease, very useful to evaluate coronary bypass grafts. It’s more predictive than a stress test, because it finds plaque; a stress test looks for blockages, but you can have a heart attack without a blockage. It’s useful to identify the cause of chest pain, particularly in the emergency department; to follow up slightly abnormal stress tests, and for preoperative testing.

Dr. Eichel showed us a lot of pictures that aren’t shown here. He finished with a list of the top ten reasons for coronary CT angiography: to find calcium where it doesn’t belong, calcium score, anomalous coronary arteries, coronary blockage, assess bypass grafts, congenital abnormalities, cardiac tumors, locate pulmonary veins for ablation, locate cardiac veins for biventricular pacemakers, and valve disease.

That was a lot of information we got!