Cardio-oncology: A new marriage of old partners

Dr Melissa Walton-Shirley


September 01, 2013

It's a sign of a great session when I have the impulse to rush home to change my clinical approach after a presentation.

Dr Daniela Cardinale from Milan, Italy, a rock star in the world of radiation-induced cardiac disease, concluded her talk with a recommendation to view a history of mediastinal radiation therapy as similar in cardiovascular risk to smoking. Much of this information, of course, is not new, but like the difference between how an academy award-winning actor vs a novice acting student delivers a line, it's the one holding the Oscar who is more likely to make an impression.

Dr Cardinale presented a review of the multiple underlying mechanisms of harm that can come to cancer patients as a result of treatment, which are not fully understood. Although cancer therapies are often life-saving, microvascular injury, decreased capillary density, and fibrosis can culminate in both diastolic and systolic dysfunction. Increased capillary permeability can lead to pericardial effusion and then constriction; and let's not forget aortic valvulopathy, most usually manifested as aortic regurgitation. For that reason, cancer patients who have completed their treatment should undergo follow up echocardiography periodically.

With regard to CAD risk, the stats were impressive based on prior trials.

Perfusion defects can be seen in up to 42% of patients following radiation (XRT). Marks et al in the International Journal of Radiation Oncology Biology Physics 2005 did a 114 patient study where the incidence of new perfusion defects was 27% to 42% and most common in left-sided breast-cancer patients. CAD may remain latent for at least 10 years, and concomitant risk factors may enhance the development. Typically it's proximal segment. Importantly, the presence of CAD doubles the risk of death, she said. She then flashed a slide of a screaming tight ostial right coronary artery (RCA) stenosis. "Is it typical atheroma or fibrosis that causes that?" an audience member later asked. "We must remember that radiation accelerates atherosclerosis," she replied. "It's an atherosclerotic process."

The presenter went on to state that "the rate of major events increases linearly with the mean dose to the heart by 7.4% per Gy. The increase in event rates started within five years after XRT and continues for at least 20 years."

Just as I was swearing off radiation therapy for myself or anyone I know and love, the presenter pointed out that this study was performed prior to the much more selective 3-D radiotherapy with far fewer complications expected.

An important caveat of this presentation included evaluation of the functionality of the left internal mammary artery (LIMA) prior to using it for CABG. I suffered a flashback during this presentation to a time when I was a fellow at Jewish Hospital in Louisville, KY. I had scrubbed in for a CABG and when the LIMA was taken down, Dr David Slater glanced up at me. Peering over his magnifying glasses, that I secretly coveted, he commented on how "puny" the mammary artery looked. He subsequently rejected it in favor of a lowly saphenous vein graft. I wonder if that patient was female and had prior XRT for breast cancer? I wondered if I was the guilty fellow that had cathed that patient and sent them to CABG without doing a LIMA injection?

Dr Cardinale produced a slide describing the Groarke et al paper published in the European Heart Journal this year. According to this data, we should start our surveillance for the presence of CAD at five years posttherapy by utilizing CT coronary calcium scoring, CCTA, or functional imaging.

After the presentation, I asked Dr Cardinale if she was aware of any guidelines that incorporated calcium scoring in females five 10 years out from radiation or chemo.

"No, I am not aware of any formal recommendations on that topic," she replied.

"If you had undergone (mediastinal) radiation therapy and/or chemo 10 years ago and had a negative calcium score, wouldn't you feel pretty good about a normal or low calcium score?"

"Yes, I would feel great about it," she replied emphatically.

I regret that time did not permit coverage of the other very excellent presentations during this session on behalf of Dr Tom Force from the US, who spoke about chemo-induced cardiomyopathy, Dr S Von Haehling, who described how advanced cancer alone can induce heart failure, and Dr T Eschenhagen, from Hamburg, who gave an excellent overview of all topics presented.

I am grateful for this excellent practice-changing presentation. I plan to modify my intake history in the office setting to include "any prior history of chest radiation or chemo" to the growing list of CAD risk factors. I'll consider ordering a calcium score to follow up on mediastinal radiation patients to get an idea of the extent of wall pathology. (I already do stress testing to evaluate for etiologies of chest discomfort). I will lobby for the incorporation of calcium scoring and/or CTA into the guidelines for routine follow-up cancer patients and lastly:

Cardiology and oncology: I now pronounce you husband and wife.


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