Scars indicated by CV magnetic resonance associated with mortality
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Scars found during CV magnetic resonance were shown to be independent predictors of all-cause and cardiac mortality in a population of patients with asymptomatic hypertrophic cardiomyopathy.
This population consisted of 243 consecutive patients with hypertrophic cardiomyopathy who were prospectively enrolled. After an initial CV magnetic resonance, 220 patients were available for clinical follow-up, which was a mean time of 1,090 days afterward. During follow-up, 20 of 220 patients died and two survived sudden cardiac death due to adequate implantable cardioverter defibrillator discharge. Sixteen of the events resulted because of cardiac reasons, whereas the remaining six were associated with cancer and accidents.
According to researchers, the presence of CV magnetic resonance-visualized scars yielded an OR of 5.47 for all-cause mortality and 8.01 for cardiac mortality. “This might be superior to classic clinical risk factors because, in our dataset, the presence of two risk factors yields an OR of 3.86 for all-cause and of 2.2 for cardiac-mortality,” they wrote. In addition, multivariable analysis revealed the presence of late gadolinium enhancement as an independent predictor of death in those with hypertrophic cardiomyopathy.
“These data support the necessity for future large longitudinal follow-up studies to definitely establish late gadolinium enhancement as an independent predictor of cardiac death in hypertrophic cardiomyopathy, as well as to evaluate the incremental prognostic value of additional CMR parameters, such as scar surface area,” the researchers concluded.
Bruder O. J Am Coll Cardiol. 2010;doi:10.1016/j.jacc.2010.05.007.
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Cardiac imaging resulted in substantial radiation exposure
Chen J. J Am Coll Cardiol. 2010;doi:10.1016/j.jacc.2010.05.014.
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Procedures involving cardiac imaging led to sizable radiation exposure and effective doses for U.S. patients, according to study findings.
Researchers used administrative claims to identify cardiac imaging procedures in nonelderly insured adults (n=952,420, aged 18-64) in five U.S. health care markets from 2005 to 2007. They estimated 3-year cumulative doses of radiation from these procedures and then calculated population-based annual rates of radiation exposure of effective doses ≤3 mSv/year, >3 mSv/year to 20 mSv/year or >20 mSv/year.
Of the study population, 90,121 (9.5%) patients underwent at least one cardiac imaging procedure using radiation and had a mean cumulative effective dose of 16.4 mSv (range 1.5-189.5 mSv). Myocardial perfusion imaging accounted for 74% of the cumulative effective dose. Overall, the annual population-based rate of receiving an effective dose of >3 mSv/year to 20 mSv/year was 89 per 1,000, and for cumulative doses >20 mSv/year, it was 3.3 per 1,000.
“Cardiac imaging procedures represent an important source of ionizing radiation in the United States,” the researchers wrote. “The overall distribution of cumulative effective doses is skewed and can lead to sizable radiation exposure for many individuals. Better strategies to minimize the radiation exposure from cardiac imaging procedures should be encouraged.”
Matthew J. Budoff, MD, and Mohit Gupta, MD, both of the Harbor UCLA Medical Center, Torrance, Calif., wrote in an accompanying editorial that further research is needed to define the most appropriate risk stratification algorithm that would provide more optimal use of the imaging modalities.
“It is clear that the benefits of treatment of advanced coronary artery disease far outweigh the induced risk of cancer after imaging in this very high risk cohort,” they concluded. “We need to move beyond radiation models, with so many assumptions, to studies documenting the real risk (if any) to the cardiac patient.”
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