Two men are lost, drifting in a hot-air balloon somewhere over a canyon. Hoping to find out where they are, one leans out and yells, "Helllloooooo! Where are we?" For the next few moments, they hear the echo fading in the distance. Then silence. Fifteen minutes pass, when an echoing voice calls back, "Helllloooooo! You're lost!!"

Visibly angered, the man who called for help blurts out, "Just our luck-we get a statistician!" Puzzled, the other man asks how he knows. "Three reasons. First, he took a long time to answer. Second, he was absolutely correct. And third, his answer was useless."

Statistics can be that way, if you expect too much from them. Survey results released last week by IMV Medical Information Division suggesting a drop in demand for cardiac cath procedures might cause some to worry that cardiac assessment is on the wane and that equipment sales might soon follow. Those concerns fade, however, when the statistics are put into context.

Many factors must be considered. The most intriguing is that alternative diagnostic methods, particularly the increased use of CT and MR, may be cutting into the need for cardiac cath as a diagnostic procedure. This possibility is buoyed by IMV results showing growth in the use of both modalities for cardiac applications. If so, a drop in overall cardiac cath procedures at sites in the U.S. might be a sign that the cardiology community is ready for a change.

If alternative means such as CT and MR are accepted for gathering data about the cardiac health of patients, cardiac cath will eventually be shunted to where invasive methods belong-in therapy. Demand for cardiac cath equipment will land softly, then likely turn back up to handle the rise in therapeutic procedures that common sense tells us will happen as the U.S. population continues to age. Meanwhile, MR and CT will likely get a boost from rapidly increasing patient demand for nontraditional applications.

The success of these two modalities for cardiac assessment will take perseverance by vendors and clinical proponents, however. The practice of medicine does not change easily. But I've done some calculations on my own, and the results are encouraging.

Factoring in known mitigators matched against the relentless march of technology in the context of common sense, on a scale of one to 10, I'd say MR and CT have a better than 50-50 chance of making it in cardiac imaging-give or take a standard deviation or two.