Bicuspid Aortic Valves and Aortic Complications

To the Editor: Dr Michelena and colleagues reported the 25-year natural history of aortic events in patients with bicuspid aortic valves (BAVs) diagnosed by echocardiography in a community cohort of 416 Olmstead County residents.¹ They concluded that the risk of aortic dissection in the entire cohort was small at 0.5%, which could be unintentionally misleading. A better question is, what was the risk of aortic dissection in patients with BAV in the cohort who had aneurysms or dilated aortas but who were not suitable for surveillance, in accordance with current American Heart Association/American College of Cardiology guidelines (<50 mm in diameter, slow growth, no valve-related indication)?²

Of the 416 patients, perhaps a much smaller number were at risk. The mean maximum aortic size for the entire group was 34 mm. Only 81 had aneurysms (aortic dimension >45 mm) de novo or during follow-up and 42 did not require surgery. Two patients underwent surgery for ascending (type A) aortic dissection. A third patient not in the community cohort but with known BAV and aneurysm also underwent surgery for type A aortic dissection. Of the 59 deaths during follow-up, it was not specified how many patients with dilated aortas died prematurely outside the hospital, where a diagnosis of dissection is usually not selected as the cause of death.

Even more concerning are the 5 sudden cardiac deaths in the community cohort, only 1 of which underwent autopsy, which was negative for dissection. Although in the remaining 4, myocardial infarction or arrhythmias were strongly suspected based on medical history, this is not proof that dissection was not the cause of death. It is known that a percentage of sudden deaths in the community that could be aneurysm-related are misdiagnosed as death from myocardial infarction. Myocardial infarction and arrhythmia are often the final lethal phenomena that are actually consequences of aortic dissection or rupture due to acute coronary or valvular insufficiency and tamponade.

Aortic complications are generally preventable with good risk stratification and counseling. We agree that it is paramount to better define risk in these patients with markers in addition to the size of the aneurysm so that the incidence of aortic catastrophe in the patients under surveillance can be reduced to as close to zero as possible.