Wait on Elective Surgery After Stroke

Pauline Anderson

July 17, 2014

Timing is important when it comes to surgery after a stroke, a new study suggests. Researchers are reporting that patients who had an ischemic stroke within 3 months before undergoing elective noncardiac surgery were at relatively high risk for cardiovascular events and mortality but that the risks stabilized after 9 months.

Interestingly, the postsurgery medical fallout was not any greater for stroke patients undergoing higher-risk surgeries than for those having lower-risk procedures, and patients with atrial fibrillation (AF) had less postsurgery risk than those without AF.

These results suggest that patients who have sustained a stroke should wait 9 months before having elective surgery, said lead author Mads E. Jørgensen, MB, research assistant, Department of Cardiology, Gentofte Hospital, University of Copenhagen, Denmark.

However, he stressed that decisions surrounding surgery timing should be made collaboratively between patients and their physicians and on an individual basis. "Doctors have to do an independent evaluation of every single patient, to weigh the pros and cons for surgery," he said.

The study results were published online July 16 in JAMA.

Risk Stratification

For the study, Danish researchers tapped into several national databases for information on surgeries, including admission and discharge dates, diagnoses, and vital statistics. The study included elective noncardiac surgeries performed in patients aged 20 years or older from 2005 to 2011.

The analysis included only patients who had ischemic stroke; those with hemorrhagic stroke or transient ischemic attack were excluded.

The investigators divided the patients into 5 subgroups: (1) those with no prior stroke and those with (2) a stroke within less than 3 months before surgery, (3) a stroke within 3 months to less than 6 months before surgery, (4) a stroke within 6 months to less than 12 months before surgery, and (5) a stroke 12 months or more before surgery.

Surgeries were stratified into low risk (eg, corneal replacement), intermediate risk (eg, a hysterectomy), and high risk (eg, a procedure involving major abdominal vessels). The primary outcome was all-cause mortality and major adverse cardiovascular events (MACE), which was a composite of nonfatal acute myocardial infarction, nonfatal ischemic stroke, and cardiovascular death. Recurrent ischemic stroke was a separate endpoint.

The analysis included 481,183 surgeries, of which 1.5% were performed in patients with a history of stroke. On average, patients with a prior stroke were 16 years older, more often men, and more frequently treated with cardiovascular medication and had a higher prevalence of comorbidities.

The incidence rate for 30-day MACE per 1000 patients was 54.4 (95% confidence interval [CI], 49.1 - 59.9) for those with any prior stroke compared with 4.1 per 1000 patients (95% CI, 3.9 - 4.2) for those with no prior stroke.

The length of time between the stroke and the surgery was an important factor. The incidence rate of 30-day ischemic stroke was 149.6-fold higher in patients with stroke less than 3 months before surgery compared with patients without stroke (119.5 [95% CI, 96.4 - 142.06] vs 0.8 [95% CI, 0.7 - 0.9] per 1000 patients).

Incidence rates of 30-day all-cause mortality were 12.6-fold higher in patients with a prior stroke within less than 3 months compared with patients without stroke (76.6 [95% CI, 58.1 - 95.0] vs 6.1 [95% CI, 5.9 - 6.4] per 1000 patients).

Stepwise Decline

A stepwise decline in risk was associated with prior stroke for longer times between the stroke event and surgery. For example, for patients with a stroke less than 3 months before surgery, the odds ratio (OR) of 30-day MACE was 14.23 (95% CI, 11.61 - 17.45) whereas the OR for stroke 12 months or more before surgery was 2.47 (95% CI, 2.07 - 2.95) compared with those without prior stroke.

"It's not actually a matter of the longer you wait, the better," commented Dr. Jørgensen. "The analysis using time elapsed between stroke and surgery as a continuous measurement showed that there is a very steep decrease in risks before 9 months, but after 9 months there are no statistically significant increased risks. And if the time increases to 12 months or 2 years, or even 5 years, there is no further decrease in risks."

The elevated risk for MACE associated with prior stroke was to a large extent driven by a high risk for recurrent stroke, with an adjusted OR of 67.6 for recurrent stroke among those with stroke less than 3 months before surgery. The risk for cardiovascular death was also increased among patients with prior stroke. There was no significant association between prior stroke and risk for acute myocardial infarction.

The ORs for MACE were the same or even higher for lower-risk surgeries. Dr. Jørgensen stressed that it's important to consider the consequences of even mild surgery following a stroke. "Keep in mind that it's relative risks within the groups, but the stroke-associated relative risk is at least as high in low- and intermediate-risk surgery as it is in high-risk surgery," he said. "Therefore you might say that no surgery is small enough to be considered safe in this group of patients."

Of note, the researchers found that a history of stroke was associated with a greater risk for 30-day MACE in patients without AF (OR, 4.74; 95% CI, 4.12 - 5.46) compared with those with AF (OR, 2.18; 95% CI, 1.64 - 2.89; P < .001).

"It's kind of a paradox that patients should have lower thromboembolic risk if they have atrial fibrillation, but it might be that there was confounding by variables not measured in our registries," such as drug use, said Dr. Jørgensen. "If you put a patient with atrial fibrillation through surgery, you are going to look into their anticoagulation and antithrombotic therapy very thoroughly," but in this study, in-hospital medication use was not captured by the registries.

As well, although the cause of the stroke was unknown, it's likely that most patients with AF had thromboembolic stroke. The authors pointed out that the risk for recurrent stroke may be lower in patients who had a stroke due to a thrombus originating in the heart as opposed to a stroke secondary to severe intracranial atherosclerosis.

While in general postsurgery risks fall off after 9 months in stroke patients, when determining timing of surgery after a stroke, it's important to consider other conditions that a patient may have, said Dr. Jørgensen. He used the example of a stroke patient who also has stomach cancer. "Postponing his surgery for 3 months may put him at even greater risk."

Because the study was observational, it's impossible to know if surgeries were postponed because of a history of stroke or whether the surgeries were performed at any given time regardless of a history of stroke, noted the authors.

Another drawback to the study was that it lacked data on measures such as pulmonary crackle, accelerating chest pain, left ventricular ejection fraction, and valvular heart disease. "We acknowledge that if a lot of patients had these conditions that we didn't know about, it could explain why they were at increased risk," said Dr. Jørgensen. "But our results are so strong and robust, and no matter what we did to them they stayed more or less the same, so we don't think that was a major problem."

Because the study patients were mostly white, generalizing the finding to other populations may not be possible, noted the authors.

Time Windows

Reached for a comment, Ralph Sacco, MD, Department of Neurology, Miller School of Medicine, University of Miami, Florida, said the study indicates that doctors should perhaps "think more clearly about the time windows" for elective procedures following stroke. "If you can delay it, it may be worth delaying it for 9 months; if you can't, it may mean that you have to do it more carefully, paying attention to stroke preventative medications around the time of surgery."

He pointed out that stroke patients who are undergoing surgery often have medications discontinued before the procedure. "One medication we are always concerned about as neurologists is antithrombotic medications. Often they get discontinued because of the risk of bleeding with surgery, so maybe it does call into question whether, if possible, we could continue antithrombotic therapy around the time of surgery, if it's safe."

Dr. Sacco also said the quality of life of stroke survivors should be considered. Cosmetic surgery, such as breast reduction, is "truly elective" and could be postponed, but putting off hip replacement or lumbar surgery may mean leaving a patient in intractable pain and severely compromising his or her enjoyment of life. "It depends on how we define elective," said Dr. Sacco.

At the end of the day, he added, the study is important in that it alerts physicians to the increased risk for stroke and vascular events among stroke survivors following elective noncardiac surgery. "Stroke survivors are always at risk for a recurrent stroke, so we need to be more careful and more diligent about ways to prevent a second stroke among our stroke survivors, particularly around the time of elective surgery."

The study was supported by grants from the Danish Agency for Science, Technology and Innovation, Novo Nordisk Foundation, and the University of Copenhagen to individual investigators. Dr. Jørgensen and Dr. Sacco have disclosed no relevant financial relationships.

JAMA. Published online July 16, 2014. Abstract

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