The safety data behind this ablation catheter

An excerpt from Collateral Damage: A Patient, a New Procedure, and the Learning Curve.

To make the scars inside Pam’s heart, Wu was “learning by burning” with the Chilli Cooled Tip ablation catheter. One big problem with cardiac catheter ablations, which they discovered as the procedures got more and more popular, was that blood tended to coagulate near the hot tip of the catheter, resulting in clots and strokes. The Chilli, a water-cooled catheter developed by Cardiac Pathways, was designed to overcome the problem.

Cardiac Pathways, an emerging device company with a lot of potential and not much else, sought approval for its new product at one of the FDA meetings held in the Grand Ballroom in the summer of 1998.

Here’s what went into the company prospectus:

“Since inception, the Company has been primarily engaged in researching, developing, testing—and obtaining regulatory clearances for—mapping and ablation catheters, equipment and systems. These catheter and equipment systems are currently the Company’s only significant potential products.”

Here was the strategy the company laid out to produce and sell actual products:

“The Company intends to build on relationships with electrophysiologists. The Company has developed strong relationships with prominent electrophysiologists worldwide who have been involved and will continue to be involved in the Company’s clinical and product development.

The Company intends to continue to build these substantial relationships through clinical investigator meetings, participation in physician-run symposia and meetings to discuss clinical issues and treatments. The Company’s strategy is to leverage these relationships with leading electrophysiologists to gain market acceptance of its products in the United States and internationally.”

It was a cultivated, compensated, and presumably leveraged Hugh Calkins who represented Cardiac Pathways before the FDA in its bid to get the Chilli Cooled Tip catheter approved. Dr. Jeff Brinker, a Calkins underling at Hopkins, was a voting member of the FDA panel that day. He had been granted a waiver. The Chilli Cooled Tip catheter was approved—despite questions about the statistical vagaries of the clinical trial and the staggering body count left in its wake.

The question before Jeff Brinker and the rest of the FDA panel that day was whether or not a Chilli Cooled-Tip ablation procedure was safe and effective. Cardiac Pathways proposed labeling cooled-tip ablation as a low-risk procedure, which didn’t sit well with panel member Dr. Cynthia Tracy.

“I think that’s something that we are going to have to reconsider,” she said, “given that complications occurred in 44 out of 150 patients.”

The death toll at the end of the study, depending on your statistical dexterity, amounted to more than two dozen people, and at least six of those patients died as a direct result of undergoing the procedure.

Calkins reported that the first patient cut down by the learning curve was a 63-year-old man. Thirty minutes after they started burning, a blood clot plugged the left main coronary artery of his heart. His blood pressure bottomed out and he died of cardiogenic shock. The second casualty came when a catheter was poked through the heart wall of a 72-year-old man. His blood pressure collapsed also, and he died a week later. Next, a 74-year-old man was killed when a catheter wire ripped his aortic valve apart.

Then a 49 year old man “underwent a successful ablation, but suffered a cerebrovascular accident that progressed to herniation and death,” according to Calkins. In other words, during the procedure, a blood vessel had burst in this 49-year-old man’s brain, and the pressure in his skull built up so much that it pushed his brain stem down into his spinal column. The patient died, but the ablation went on the books as a success.

FDA Panel member Dr. Tony Simmons of Wake Forest University recommended that Cardiac Pathways change the patient counseling information for the Chilli Cooled-Tip ablation catheter “to more accurately reflect the risk and the lack of demonstrated effectiveness overall.”

Dr. Simmons, who had determined that the Chilli catheter was no improvement over similar products already on the market, was curious about the reasons for the study’s high casualty rate. “I would have thought that, well, when a significant percentage of the patients died, I mean… there should have been some autopsy data, right?”

Maybe there should have been, but there wasn’t.

Even though it was his Hopkins boss Hugh Calkins asking him to approve the Chilli Cooled-Tip catheter, panel member Jeff Brinker had trouble squaring the lack of safety data.

They didn’t really get any insights from the clinical trial, and you really couldn’t trust the professional journal articles to assess the risks, Brinker said, because in the literature, “people sort of cherry pick what they do, and they write that up.”

To really find out how risky this thing was, you’d have to “get a bigger denominator,” he said. “So, I think that we just need a couple of hundred patients who get an ablation so we can really look at what the procedural risk is.”

Brinker wanted Cardiac Pathways, once the procedure was established practice, to conduct post-market surveillance, which meant keeping a running casualty list and periodically reporting it to the FDA. You’d find out how risky it was once doctors across the country started doing the procedure by the hundreds. Just get it out there and let them start doing it and see what happens.

“Do you mean,” asked Dr. Simmons, “a follow-up on the alive or dead thing?”

Just so, said Brinker.

And that’s what they did. With little evidence of its safety or effectiveness, and despite the lack of autopsy data on those who died so that others could make a killing, the Chilli Cooled-Tip catheter was approved, and it went on to enjoy great financial success in the marketplace as a device to treat atrial fibrillation (off-label).

Boston Scientific, Inc. eventually bought Cardiac Pathways for $115 million in cash.

Dan Walter is the author of Collateral Damage: A Patient, a New Procedure, and the Learning Curve.

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