AJC: More data support safety of echo contrast

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Despite black box warnings from the FDA regarding echocardiography contrast agents, studies have consistently confirmed their safety. Now, a meta-analysis published July 23 in the American Journal of Cardiology further supports that these agents do not increase incidences of either myocardial infarction (MI) or death.

The contrast agents became contraindicated for patients with acute cardiopulmonary syndromes, severe pulmonary hypertension and QT prolongation after four deaths were reported 30 minutes after an ultrasound contrast agent was administered.

In May 2008, these warnings were lifted after it was proven that these adverse events were related to a patient’s underlying medical conditions; yet the FDA continued to issue warnings.

To further evaluate the potential adverse effects of the use of contrast agents, Owais A. Khawaja, MD, of the Providence Hospital in Southfield, Mich., and colleagues performed a meta-analysis of eight studies that reported all-cause mortality or both all-cause mortality and MI, after contrast agents were administered for echocardiography.

The researchers searched MEDLINE, EMBASE, BIOSIS and Cochrane databases and identified eight relevant studies—all eight studies recorded all-cause mortality and four recorded rates of MI in addition to mortality.

The studies that recorded for all-cause mortality included a cohort of 5.29 million patients—211,162 patients in the contrast agent arm and 5.08 million in the non-contrast arm.

Results showed that the incident rate of all-cause mortality for patients in the contrast agent arm was 0.34 percent, compared with 0.9 percent in the control arm.

A total of 101,767 patients were enrolled within the four studies that reported rates of MI, 57,264 in the contrast arm and 44,503 in the non-contrast arm. The researchers found the incidence rate of MI to be 0.15 percent in the contrast agent arm, compared with 0.2 percent in the non-contrast group.

The odds ratios for all-cause mortality for each study were statistically insignificant, as were the incidence rate of allergic/ anaphylactic reactions to those administered contrast agents.

“From the data included in the present meta-analysis of over 200,000 contrast doses, our results support the idea that ultrasound contrast agents are safe and do not increase the incidence of all-cause mortality or MI,” the authors wrote.

They noted that in one study, more than 50 percent of the contrast group (more than 6,000 patients) had one or more contraindications, but there were no reports of death at 24 hours.

“Differences in the patient population (inpatient versus outpatient), testing modality (at rest versus stress), sample size and follow-up might have affected the final results by reducing the event ratio; however, despite these examples of heterogeneity, the overall result still favored the lack of an increased risk of the primary end point, even in the high-risk patient population.”