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Mediastinal irradiation may affect diastolic function
We performed this study because of a concern over the effect of
mediastinal irradiation on sudden death. We know that
coronary disease is common following mediastinal irradiation, yet is
often asymptomatic and not detected with exercise testing. We felt
that mediastinal irradiation may also affect diastolic function
that could be measured non-invasively with echocardiography. If
abnormal diastolic function is a marker of risk for future cardiac events, patients
with diastolic dysfunction can be identified, evaluated further
with angiography and treated.
We used data from a study of asymptomatic patients who had received at least 35 Gy to
the mediastinum for treatment of Hodgkin disease. Each patient underwent
resting echocardiography, stress echocardiography, and nuclear
scintigraphy. Survival free from cardiac events was determined during
3.2 years of follow-up. Although there is little consensus regarding
what constitutes diastolic function in patients under 45 (the mean age
of our cohort was 42) standard measures of diastolic dysfunction (based
on E/A mitral velocity ratios, E wave decelleration time and pulmonary vein flow patterns) indicated that diastolic dysfunction was
common. Diastolic dysfunction was considered mild in 26 (9%) and
moderate in 14 (5%). Exercise-induced ischemia was more common in
patients with diastolic dysfunction (23%) than those with normal
diastolic function (11%, P = .008). We found that diastolic dysfunction
was indeed a risk factor for cardiac events or death. After
adjustment for patient demographics, clinical characteristics, and
radiation history, patients with diastolic dysfunction had worse
event-free survival than patients with normal function (hazard ratio
1.66, 95% CI 1.06-2.4). The clinical implication is that screening
with Doppler echocardiography may be helpful in identifying patients at
risk for subsequent cardiac events. Subsequent stress testing and
possibly angiography should be considered for these patients. Bibliographical Reference:
Paul Heidenreich Cardiology Section, VA Palo Alto Health Care System, Stanford University, Stanford, California
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