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Dr W. Moore (Los Angeles, Calif): How do we know that, in fact, that there has been myocardial damage just because you happen to have an asymptomatic troponin release in the absence of EKG changes?

Our cardiologists often describe the so called troponin leak phenomenon, particularly when there may be an episode of hypertension in the perioperative interval. I think your increased incidence of mortality may simply represent a higher risk group in which the troponin leak population occurred. You showed that there was a higher incidence of prior myocardial infarction and other comorbidities in the troponin leak group. Therefore I wonder if the troponin event is simply a marker for the higher risk group rather than a morbid event in of itself?

Dr Schouten: As shown on the slides on pathophysiology of troponin release, there must be a compromised membrane of the cardiomyocytes for troponin to be released into the bloodstream. This implies that there must be cardiac damage one way or the other.

We also did a subgroup analysis for patients who stayed at the ICU for at least two days after surgery, more or less the critically ill patients with episodes of hypotension, and also, in that group of patients, those with troponin release did much worse than patients without troponin release. While the exact pathophysiology is not entirely clear for this group of patients, the main message is that if you have a patient with cardiac troponin release, either it's symptomatic or asymptomatic, they do much worse on the long term. These patients probably will benefit from more aggressive medical therapy and more aggressive follow-up on the long term.

Dr J. Ricotta (Washington, DC): I was actually going to ask you to elaborate on that last question. In your units, do you have a protocol for how you evaluate these patients after you find that they have asymptomatic troponin release. Do you have a standard algorithm for evaluation and management?

Dr Schouten: Currently we are performing another study in this patient population with asymptomatic cardiac troponin T release. It's called the DECREASE VII trial. And what we do in that trial is that we randomize patients who have asymptomatic cardiac troponin release to receive either clopidogrel on top of beta blockers, statins and aspirin, or placebo on top of this medication.

In terms of cardiac stress testing or coronary angiography, it depends on whether or not the patient will get eventually EKG abnormalities. If the patient remains asymptomatic and has no EKG abnormalities, we will not perform any other additional cardiac evaluation or cardiac tests.

Dr P. Goodney (Lebanon, NH): We studied similar questions in our vascular study group in Northern New England. One of the questions we struggled with was a lack of a multivariate finding for beta blockers and statins. I noticed your model similarly didn't include those medical regimens. I thought you might comment on that.

Dr Schouten: At our unit all patients are on beta blockers, so it is impossible to find any benefit or harm of beta blockers in this study. What we have found in this study in terms of medication use—I did not include it in this presentation because of time restraints is that patients who were not on statins, which were approximately 30% of the patients, had a worse outcome than patients on statins. The odds ratio was approximately 0.65. So statins seem to work. But on the other hand, nowadays, all our patients will get statins anyway.

Dr P. Gloviczki (Rochester, Minn): Have you looked at preoperative cardiac variables, cardiac risk factors, and would they predict your elevated troponin release?

Dr Schouten: One of the slides showed a multivariate analysis for predictors of asymptomatic cardiac troponin release, and these risk factors were more or less the same as for more hard endpoints like myocardial infarction and cardiac deaths.

Dr F. Mussa (New York, NY): Along the same line of Dr. Gloviczki's question, did you go back and change your preoperative workup for those patients based on your troponin release? Nowadays, we're doing less extensive workup for patients with stable coronary disease undergoing vascular or endovascular procedures.

Dr Schouten: No, we did not change our preoperative workup based on these study results. Our current preoperative policy is based on earlier DECREASE studies, and in particular DECREASE II: patients with 1 risk factor can undergo surgery quite safely with beta blockers and statins. Also patients with 2 risk factors will benefit from statins and beta blockers and can undergo vascular surgery quite safely.

The problem is with patients who have 3 or more risk factors. In those patients we perform cardiac stress testing, in all patients. But that's not something that we've investigated in this study and it's not something which we will change based on these study results.