LOS ANGELES – Hodgkin’s lymphoma survivors who underwent mediastinal radiation therapy for their cancer have a high prevalence of occult cardiovascular disease, a systematic examination of 182 patients showed.
Among 182 asymptomatic, radiation-treated Hodgkin’s lymphoma patients with no prior history of cardiovascular disease, 47 (26%) showed signs of "significant" coronary artery disease (CAD), valvular disease, or left ventricular systolic dysfunction with screening echocardiography done at least 5 years and an average of 15 years after finishing radiation therapy, Dr. Ming Hui Chen reported at the annual scientific sessions of the American Heart Association.
Patients had this high prevalence despite their relatively young age, which ranged from 21 to 65 years and averaged 43 years. Among the subgroup with identified coronary or valvular disease, the average age was 48, ranging from 36 to 65 years, said Dr. Chen, a cardiologist and associate director of the noninvasive cardiac laboratory at Brigham and Women’s Hospital in Boston.
Her analysis also showed that hypertension was the only modifiable risk factor associated with screening-detected CAD and valve disease in these patients. Based on that, "blood pressure modification would likely result in considerable calculated risk reduction for CAD and valve disease in Hodgkin’s lymphoma survivors cured by mediastinal radiation," she concluded.
"The key question is, does radiation directly cause [CAD or valve disease] or does it do so indirectly through hypertension and other cardiac risk factors? Does the hypertension reflect an interaction with arterial stiffness caused by radiation itself?" she asked.
It’s "quite possible" that the hypertension is caused by radiation of "the most distensible part of the arterial system that is mostly responsible for buffering the pulses of the heart," commented Dr. Michael O’Rourke. The problem with this hypothesis is that, if true, "you would expect more systolic than diastolic hypertension," which wasn’t what the data showed, said Dr. O’Rourke, professor of medicine at the University of New South Wales in Sydney.
Dr. Chen and her associates performed screening echocardiography on long-term survivors of Hodgkin’s lymphoma who received mediastinal radiation therapy because results from prior studies had shown that cardiovascular disease is three to five times more prevalent in this population, but despite that, routine screening of these patients for cardiovascular disease is rarely done, she said.
They examined 182 former patients treated for Hodgkin’s lymphoma with mediastinal radiation at any of four Boston-area hospitals during 1967-2006 who were asymptomatic and had no history of cardiovascular disease. All patients underwent transthoracic and stress echocardiographic examinations, and those with findings suggestive of ischemic coronary disease also underwent confirmatory angiography. During cancer treatment the patients had received an average total radiation dose of 3,960 Gy.
Screening identified 24 patients with CAD or valvular disease, and 26 with left ventricular systolic dysfunction (3 of the 47 affected patients had both categories of cardiovascular disease). Some patients had valve disease so advanced that they needed emergency surgery. The most common type of valve disease was aortic stenosis.
Among the people examined, 81% had at least one modifiable cardiac risk factor, including 24 patients with a history of hypertension, and another 24 with a new diagnosis of hypertension. Analysis of all the identified cardiovascular disease risk factors showed that hypertension, an elevated level of high-sensitivity C-reactive protein, and older age were each significantly more prevalent among patients with CAD or valve disease, compared with those without.
But results from a multivariate-adjusted analysis showed that hypertension was the only modifiable risk factor to significantly link with CAD or valve disease. Patients with hypertension were 4.5-fold more likely to have CAD or valve disease, compared with patients without hypertension.
The analysis also showed that for each 5-mm Hg rise in systolic blood pressure, the rate of coronary and valve disease rose by 29%, and for each 5 mm Hg rise in diastolic pressure, the rate of disease rose by 35%, both statistically significant effects, Dr. Chen reported.
Dr. Chen said that she has no disclosures. Dr. O’Rourke is medical director and cofounder of AtCor Medical.