By Michael H. Crawford, MD, Editor

SYNOPSIS: Interrogation of Danish administrative registry data demonstrated that a stroke within three to four months of aortic valve surgery was associated with a higher rate of perioperative stroke.

SOURCES: Andreasen C, Jørgensen ME, Gislason GH, et al. Association of timing of aortic valve replacement surgery after stroke with risk of recurrent stroke and mortality. JAMA Cardiol 2018;3:506-513.

Mullen MT, Messé SR. Aortic valve surgery after recent stroke: Patience is a virtue. JAMA Cardiol 2018;3:514-515.

Prior stroke is a risk factor for perioperative stroke with surgical aortic valve (AV) replacement, but little is known about this risk in relation to time since stroke. Andreasen et al interrogated Danish administrative registry data for patients undergoing AV replacement between 1996 and 2014. Those with multivalve surgery or infective endocarditis within one year prior to surgery were excluded. The primary outcome was major adverse cardiovascular events (MACE) 30 days post-operative. The study population was divided into four groups: no prior stroke, prior stroke < 3 months, three to 12 months prior, and > 12 months prior.

Of the 14,030 patients identified, 616 had prior stroke and 13,414 did not. Most patients were men with a mean age of about 70 years and had received bioprosthetic valves. Patients with prior stroke had more comorbidities such as atrial fibrillation and carotid artery disease. MACE occurred in 5.7% of patients without compared to 23% in those with prior stroke < 3 months before surgery (adjusted odds ratio [OR], 4.57; 95% confidence interval [CI], 3.24-6.44). Also, ischemic stroke was more frequent in the latter group (OR, 14.7; 95%CI, 9.7-22.3), but not 30-day, all-cause mortality (OR, 1.45; 95% CI, 0.83-2.54). The risk of all adverse outcomes declined with time and was stable after two to four months. The authors concluded that prior stroke is a major risk factor for perioperative stroke in patients undergoing surgical AV replacement, especially if it occurred < 3 months prior to surgery.

COMMENTARY

It is not surprising that prior stroke is a risk factor for adverse outcomes with cardiac surgery since it is part of the STS and EuroScore risk calculators. What is unclear was the time frame of the prior stroke regarding the surgery. The risk of recurrent stroke was highest when the prior stroke was < 3 months ago, but declined after that and reached a nadir at four months. Andreasen et al considered it reasonable to consider surgery three months after a stroke. However, since this was an observational study with no control group, the results have to be considered hypothesis-generating.

There are some interesting aspects of the study. The overall stroke rate was about 1% for the entire group, but increased to 2% if coronary bypass was performed in addition to AV replacement. Also, neither atrial fibrillation nor carotid artery disease was related to the occurrence of perioperative stroke, but atrial fibrillation did increase the risk of MACE, as has been shown before. Few patients had transcutaneously delivered valves, but their results were similar.

There are weaknesses to this study beyond its observational nature. The number of patients with prior stroke was small relative to the total population. Perhaps this was because prior stroke would increase the preoperative risk score and remove some patients from surgery consideration. Since this was an administrative database study, key clinical details are unavailable, and adverse events likely were underestimated. Those who underwent surgery despite a recent stroke were probably sicker, in need of urgent surgery, and probably higher-risk patients in general. The study period spanned almost two decades, so it may not accurately reflect today’s practice.

Despite these limitations, waiting to perform AV replacement surgery for at least three, preferably four, months after stroke probably will result in fewer perioperative strokes.