Challenges in the management of aortic stenosis
PCI FOR CONCOMITANT SEVERE CORONARY ARTERY DISEASE
The risk factors for aortic stenosis are similar to those for coronary artery disease, and many patients with moderate or severe aortic stenosis also have significant coronary disease. These patients are traditionally referred for combined surgical aortic valve replacement and coronary artery bypass grafting.
Patients who have the combination of both diseases have a worse prognosis, and adding coronary artery bypass grafting to surgical aortic valve replacement increases the perioperative mortality rate.7
With advances in transcatheter aortic valve replacement, attention has turned to managing concomitant coronary artery disease percutaneously as well. Until recently, however, there were few data on the safety of percutaneous coronary intervention (PCI) in patients with severe aortic stenosis.
Goel et al8 analyzed the outcomes of 254 patients with severe aortic stenosis who underwent PCI at our institution, compared with a propensity-matched group of 508 patients without aortic stenosis undergoing PCI. Overall, the 30-day mortality rate did not differ significantly between the two groups (4.3% vs 4.7%, P = .20), nor did the rate of complications such as contrast nephropathy, periprocedural myocardial infarction, and hemodynamic compromise during the procedure. In subgroup analysis, patients who had severe aortic stenosis and ejection fractions of 30% or less had a significantly higher risk of death than those with ejection fractions greater than 30% (15.4% vs 1.2%, P < .001).
Comment. This information is important, since many patients with severe aortic stenosis also have coronary artery disease. Certainly, for patients with significant coronary artery disease and severe aortic stenosis who cannot undergo surgery, the findings are especially encouraging with respect to the safety of PCI.
The findings also suggest that in patients for whom transcatheter aortic valve replacement can be performed in a timely fashion, a completely percutaneous approach to treating aortic stenosis and coronary artery disease may be reasonable. This hypothesis must be further investigated, but the preliminary data are encouraging.
TRANSCATHETER AORTIC VALVE REPLACEMENT IN LOWER-RISK PATIENTS
The PARTNER (Placement of Aortic Transcatheter Valves) trial showed that transcatheter aortic valve replacement was superior to medical therapy alone for patients who cannot undergo surgery, and not inferior to surgical aortic valve replacement for patients at high surgical risk, ie, a Society of Thoracic Surgeons (STS) mortality risk score greater than 10%.9
Given these encouraging results, the PARTNER II trial is now randomizing patients who are at moderate surgical risk (STS score > 4%) to surgical vs transcatheter aortic valve replacement.
Since transcatheter aortic valve replacement has been performed in Europe under the Conformité Européenne (CE) marking since 2007, diffusion of the procedure there has occurred in a more rapid fashion than in the United States. As a result, a number of patients with low or moderate surgical risk have undergone this procedure.
Lange et al10 summarized their experience at a single center in Munich, Germany, with an eye toward patient selection and surgical risk. Between 2007 and 2010, 420 patients underwent transcatheter aortic valve replacement. When the authors divided the cases into quartiles according to the sequence in which they were seen, they found a statistically significant decline in the STS score over time, from 7.1% in the earliest quartile to 4.8% in the latest quartile (P < .001), indicating the procedure was diffusing into lower-risk groups. With respect to outcome, the 6-month mortality rate declined from 23.5% to 12.4%; this was likely due to a combination of patient-related factors (more patients at lower risk over time), device advances, and greater operator experience. Also of note, only 70% of patients in the latest quartile were intubated for the procedure.
Comment. Diffusion of transcatheter aortic valve replacement in the United States is following a thoughtful path, with patients being assessed by “heart teams” of clinical cardiologists, interventional cardiologists, imaging cardiologists, and cardiac surgeons, and with strict criteria for site approval to perform commercial placement of the Edwards Sapien valve. In keeping with this controlled process, future randomized studies (such as PARTNER II) of transcatheter aortic valve replacement in lower-risk patients will be necessary before this procedure can be widely applied to this patient group. The results are, therefore, eagerly anticipated, but preliminary experience from Europe is encouraging.
