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Radiation-associated CAD confers increased mortality risk after PCI
Patients with CAD linked to previous external beam radiation therapy face increased short- and long-term risk for mortality following PCI compared with patients with standard atherosclerotic CAD.
“People are living a lot longer, with substantial improvements in treatment, including radiation,” Milind Y. Desai, MD, staff cardiologist in the section of cardiovascular imaging in the Robert and Suzanne Tomsich department of cardiovascular medicine at the Sydell and Arnold Miller Family Heart and Vascular Institute at Cleveland Clinic, told Cardiology Today’s Intervention. “For every treatment, there’s a side effect; for every action, there’s a reaction. We’re now seeing the ramifications of things that happened 15 to 20 years ago.”
Milind Y. Desai
For the observational study, Desai and colleagues evaluated 314 consecutive PCI patients treated at a tertiary care center from 2000 to 2012. The patient population comprised two equally matched groups: one group with diagnosed CAD associated with previous external beam radiation therapy (EBRT; n = 157) and a comparison group of patients with typical atherosclerotic CAD (n = 157) with no previous EBRT exposure, each matched 1:1 with a patient in the EBRT group. The following measures were used to fully match the patients in the two groups: age within 5 years, sex, target artery during PCI and type of PCI performed (balloon angioplasty, bare-metal stent or drug-eluting stent).
The primary endpoint was all-cause mortality. CV mortality was designated as the study’s secondary endpoint.
Predictive association
During an average follow-up of 6.6 years after PCI, 101 deaths occurred. Of those, 59 (59%) were in the radiation-associated CAD group and 42 (42%) in the comparison group (P = .04). A multivariable Cox proportional hazard model for all-cause mortality revealed a persistent, independently predictive association between previous EBRT and all-cause mortality (HR = 1.85; 95% CI, 1.21-2.85).
Other variables found to be independently predictive of increased all-cause mortality included PCI with balloon angioplasty or BMS placement vs. DES placement (HR = 2.5; 95% CI, 1.61-3.97), SYNTAX score of at least 11 (sample median; HR = 1.99; 95% CI, 1.32-3.04), NYHA functional class III or IV (HR = 1.83; 95% CI, 1.15-2.91), smoking history (HR = 1.88; 95% CI, 1.1-3.09) and age 65 years or older (HR = 1.7; 95% CI, 1.07-2.07).
CV mortality occurred in 69 patients, with 37 (54%) in the radiation-associated CAD group and 32 (46%) in the comparison group. Moreover, 63% of the deaths in the radiation-associated CAD group (n = 37) were determined to be related to CV causes. An unmatched analysis adjusting for age, sex, NYHA functional class III or IV at time of PCI, SYNTAX score and PCI type found previous EBRT exposure to be a persistent independent predictor of CV mortality (adjusted HR = 1.7; 95% CI, 1.06-2.89).
Significantly worse outcomes
“In comparing these matched groups, the outcomes were still significantly worse in the [EBRT] group compared to the controls,” Desai said.
This study is the first to identify previous EBRT as an independent risk factor for all-cause and CV death after PCI, according to the researchers.
“The important thing is the recognition of this [EBRT-associated CAD] as an entity; it is different from garden-variety CAD,” Desai said. “It is important to recognize this when treating these patients, and more importantly, it is important for patients who have had radiation to be checked for CAD within about 5 years.” – by Jennifer Byrne
For more information:
Milind Y. Desai, MD, can be reached at Department of Cardiovascular Medicine, Heart and Vascular Institute, Cleveland Clinic, 9500 Euclid Ave., Desk J1-5, Cleveland, OH 44195; email: desaim2@ccf.org.
Disclosure: The researchers report no relevant financial disclosures.