Predicting Mortality Risk: Role of New Troponin Assay

Arefa Cassoobhoy, MD, MPH; Melissa Walton-Shirley, MD


April 14, 2017

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Arefa Cassoobhoy, MD, MPH: Hi, everyone. My name is Arefa Cassoobhoy. I am a practicing internist and a medical editor at Medscape and WebMD. We are discussing the recent American College of Cardiology (ACC) 2017 Scientific Sessions and the key studies with implications for those of us practicing in primary care. I am pleased to be joined by Dr Melissa Walton-Shirley, a cardiologist and contributor to Medscape.

In part 1 of our discussion, we spoke about the FOURIER trial. Now we will turn our attention to the Vascular Events in Noncardiac Surgery Patients Cohort Evaluation (VISION) trial.[1]

Predicting Mortality Risk Using High-Sensitivity Troponin Assays: VISION Trial

Dr Cassoobhoy: VISION examined the role of new high-sensitivity troponin T assays in predicting myocardial injury and mortality risk after noncardiac surgery. What do we as PCPs need to know about these assays?

Melissa Walton-Shirley, MD: This was a great trial and I thought it was well done. It was a prospective, observational trial looking at levels of troponin T which were associated with 30-day mortality. The trialists looked at over 21,000 patients with or without coronary disease who were undergoing noncardiac surgery. They checked the high-sensitivity troponin T (hs-TnT) levels at 6 and 12 hours post-op and then daily for 3 days. They did have a little glitch: About halfway through the trial, they recognized that they had not checked presurgery troponin levels for trends [in all patients].

They found that 1.4% of patients died during the study period. That may not sound like a lot, but there were 300 deaths and those patients need to be looked at. Patients with an hs-TnT level < 5 ng/L had a 0.1% risk for death. This risk increased incrementally with higher levels. A level of ≥ 20 ng/L to 64 ng/L was associated with a 3% absolute risk for mortality; 65 ng/L to < 1000 ng/L had 9.1% risk for mortality; but ≥ 1000 ng/L had a 29.6% risk for mortality.

Dr Cassoobhoy: The numbers were astounding.

Dr Walton-Shirley: Absolutely. The other thing that was interesting is that 13.8% of these individuals had their peak troponin level before their surgical procedure was performed. [Editor's note: Only 40.4% of patients had a preoperative hs-TnT measurement, so this peak was assessed in that percentage of the overall study population.]

It should be emphasized that the Elecsys Troponin T Gen 5 STAT assay (Roche Diagnostics) used in this trial is not yet commercially available, although the US Food and Drug Administration (FDA) has recently approved it. We will have the FDA package insert in April.

After this is available to us, I think it is going to be practice-changing. You could, however, in my opinion, do the same trending with the troponin assays that we have available to us now.

'How Are We Missing Such Significant Cardiac Injury?'

Dr Cassoobhoy: In this trial, 18% of the study population had sustained cardiac injury. And astonishingly, in 93% of that group, the cardiac event was missed. I don't understand how this is happening. How are we missing such significant cardiac injury?

Dr Walton-Shirley: I think if you do not seek, you will not find. We have to look. It is a lesson for me as well, because when I see a patient for preoperative risk assessment, I always get a troponin level. But I only get a repeat troponin if the patient had an event or became unstable in some way, such as with chest discomfort, etc. These troponin leaks are happening more often than we think. We probably need to check a postoperative troponin on everybody at risk.

Should We Change Patient Management?

Dr Cassoobhoy: How will that change our management? Is it a matter of aspirin or statins? What do you think?

Dr Walton-Shirley: At the ground level, we probably should be adding a troponin level to our preoperative and postoperative orders. We will have to treat these patients with aspirin preoperatively when appropriate. You cannot do that oftentimes with a urologic or a neurologic procedure. Our neurosurgeons and urologists are sticklers about those things because they deal with highly vascular organs. They could get into a lot of trouble with bleeding, intracranial hemorrhage, etc.

I think these results also emphasize the need to check postoperative ECGs and to make sure these patients are on telemetry. A lot of the time when I am called to see a patient for a preoperative risk assessment, they do not even have an ECG on the chart. They are not on telemetry. We do not have a baseline echocardiogram. An anesthesiologist needs to know whether they have room to add 2 or 3 L of saline for hypotension intraoperatively, or do we just need to add some Neo-Synephrine (phenylephrine) after a short bolus? All of that rests on left ventricular function.

Sometimes we do not have time to get the patient ready appropriately. We need to risk-stratify patients with this higher troponin leak postoperatively where appropriate. They need a predischarge nuclear stress evaluation and/or cardiac catheterization, depending upon their status postoperatively.

'Know Where You Are Going'

Dr Cassoobhoy: Thank you so much for telling us about this important trial. This is going to be a game changer for the noncardiac surgical population. In the meantime, before these hs-TnT assays are available, are you recommending [ordering] the troponin tests that are currently available?

Dr Walton-Shirley: Absolutely. It is always good to have a baseline. We do that routinely. You cannot know where you are going until you know where you have been.

Dr Cassoobhoy: Thank you, Melissa. It is always a pleasure to talk to you.

Dr Walton-Shirley: Great to talk to you too. Thank you for the invitation.


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