In fact, immediate angiography may not be the wisest approach, especially when the risk of neurological deficits is taken into account, researchers say.
The TOMAHAWK randomized trial of 554 patients found a death rate of 54% in the immediate-angiography group versus 46% with delayed angiography (P=0.06).
When the team included the risk of severe neurologic deficit, the rates were 64% with immediate angiography and 56% delayed angiography. The risk was 16% higher for the immediate-treatment group, with a 95% confidence interval of 1.00 to 1.34.
Doctors usually work to get cardiac arrest patients into the catheterization lab as quickly as possible but "it turns out this might not be the best approach in the vast majority of patients," chief author Dr. Steffen Desch, a professor of cardiology at the University of Leipzig in Germany, told Reuters Health by phone.
When cardiac arrest occurs, acute coronary lesions are usually the culprit if doctors subsequently see an ST-segment elevation on an ECG.
But most resuscitated patients don't have an ST-segment elevation and both cardiac and noncardiac causes can underlie the arrest.
Why speedy catheterization might produce worse outcomes is not known. The TOMAHAWK team didn't study the precise reasons patients did poorly.
"Theoretically you've got the complications of the procedure - for example renal failure and all the contrast-related issues that might be a reason," said Dr. Desch. "If you automatically go to the cath lab, you have about 60% of patients who do not have coronary disease, or at least not a lesion. You expose these patients to the risk of the procedure, and they don't have any benefit at all."
In addition, "If you don't have acute coronary syndrome as the cause of the event, you probably delay the subsequent diagnosis and correct treatment. For example, if you have brain bleeding, the patient might get some blood thinners and you could delay the correct diagnosis and worsen the clinical situation. That might explain the trend where we see some harm in the immediate group. But that's just a hypothesis," he said.
The findings were released at the European Society of Cardiology Congress 2021 and simultaneously in the New England Journal of Medicine.
Only 38% of the patients, all treated at 31 sites in Germany and Denmark, had known coronary-artery disease.
Patients in the immediate-angiography group went to the catheterization laboratory after a median of 2.9 hours following their cardiac arrest.
Those in the control group went directly to the intensive-care unit. If the treating physician determined that there was a high likelihood that the cause was an acute coronary problem, the patient could get angiography if 24 hours had passed since the cardiac arrest, unless there was evidence of substantial myocardial damage.
Just over 62% of the patients in the delayed-angiography group ended up with angiography. When it occurred, the median time to get it was 46.9 hours after cardiac arrest.
It was up to the operator to choose between coronary-artery bypass grafting or percutaneous coronary intervention, and which type of stent to use.
The speed of angiography did not affect the odds of stroke, peak troponin values, the risk of moderate or severe bleeding, or the odds of needing renal-replacement therapy.
The results are comparable to the earlier COACT trial that showed similar outcomes after cardiac arrest when the survivors were followed for 90 days and one year.
For that reason, Dr. Desch said, he was expecting neutral results in the TOMAHAWK comparison of the two techniques.
He predicted that cardiologists will welcome the news because "they don't have to feel this intense pressure to do something in the middle of the night."
"If you are an interventional cardiologist or an intensivist and you're faced with a patient with an out-of-hospital cardiac arrest with possible cardiac origin but without ST elevation, you don't have to speed things up. You can take your time, do further diagnostics, get your lab markers, maybe get your CT scan or echo and then, after a day or two or three, decide if there is still a high likelihood of a coronary cause. Then you can go on to coronary angiography. This does not have to be done in the first few hours," he said.
And if patients or family members complain that there's been no rush to cardiac catheterization, Dr. Desch said, "I would say to them it's because we didn't want to do harm."
SOURCE: https://bit.ly/2UXuOrE The New England Journal of Medicine, online August 29, 2021.
By Gene Emery
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