Are ARBs safe in patients experiencing angioedema on an ACE inhibitor?

This was the topic of a recent review in CCJM.

ARBs are known to be associated with angioedema but the risk is quite low. The mechanism is unknown and there is no plausible mechanism in common with ACEIs. It cannot be established conclusively from empirical evidence that there is any true cross sensitivity. However, given the speculation that patients with ACEI induced angioedema may have an “allergic diathesis” predisposing them to angioedema from unrelated mechanisms the authors of the review advise caution, as do various other experts and guidelines. These cautions include patient education as to possible risk and shared decision making. For appropriate indications the benefits of ARBs are substantial in patients ACEI intolerant and must be weighed against the very small risk.