From the Research
For a patient with severe contrast-induced angina despite premedication, the primary recommendation is to consider alternative imaging approaches, such as ventilation-perfusion (V/Q) scanning, instead of CTA PE, to avoid the risk of recurrent angina. When considering CTA PE, several precautions should be taken to minimize the risk of severe angina.
- Administer an enhanced premedication regimen including oral prednisone (50 mg) at 13,7, and 1 hour before the procedure, diphenhydramine (50 mg) and famotidine (20 mg) 1 hour before, and have sublingual nitroglycerin (0.4 mg) immediately available during the scan, as suggested by previous studies 1.
- Ensure continuous cardiac monitoring throughout the procedure with emergency medications and resuscitation equipment readily accessible.
- Consider using the lowest possible contrast dose with iso-osmolar contrast agents like iodixanol, which may cause less hemodynamic stress, as shown in a study on low tube voltage and low-iodine-concentration contrast agent for pulmonary CT angiography 2.
- Have a cardiologist present during the procedure and maintain IV access for immediate intervention if needed.
- Most importantly, changing the contrast media to one without a common carbamoyl side chain is recommended, as it significantly lowers the recurrence rate of hypersensitivity reactions, including severe angina, as demonstrated in a recent study 3. The severe angina reaction likely results from contrast-induced vasospasm of coronary arteries, and these precautions aim to minimize this risk while maintaining diagnostic accuracy. For many patients, the risk-benefit analysis may favor non-contrast alternatives given the potentially life-threatening nature of contrast-induced angina. It is also worth noting that patients with a history of moderate-to-severe hypersensitivity reactions to low-osmolar iodinated contrast media have a higher recurrence rate of severe reactions, despite premedication, and changing the implicated contrast media can reduce this risk, as found in a multicentre retrospective cohort study 4.