About False Positive STEMI Activations....

I write this blog with caution, as I am afraid I am opening myself up or criticism and ridicule. But I feel as if there is an issue which interventional cardiologists are afraid to raise, except perhaps in venting to sympathetic audiences (spouses and other interventional cardiologists). I have heard the whispered conversations, and have spoken frankly with prominent interventional cardiologists who feel there is an under-addressed issue in our field. This issue is the “problem” of false positive STEMI activations. I put the word "problem" in quotations because I think we are all afraid to raise this issue. We recognize that it is part of the solution of another, more important problem: delays in door-to-balloon times. Since door-to-balloon time delays are associated with increased mortality, it is difficult to address problems resulting from improvements in door-to-balloon times. So this issue may not be raised, or when it is, there is an immediate response of “the price we pay for not missing any STEMI’s is that we also cath patients who don’t have coronary artery occlusions.” The point is evident to everyone, but the mere raising of the objection states that the issue of false positive activation is not regarded as having sufficient value to get beyond that point. Perhaps the reader will indulge me a little bit, and allow me go a bit beyond that obvious and important concern. What might be the disadvantage of false positive activations (anecdotally reported to be as high as 60% at some hospitals)? First, of course, there could be complications from the coronary angiogram, including the usual suspects of vascular and renal problems. Admittedly, this should be quite low. Of course, perhaps one of the more common reasons for a false positive activation is due to a patient who survived a cardiac arrest, who might therefore have some secondary end-organ problems, so the contrast might actually be particularly harmful. (Hopefully someday studies will direct us towards whether or not there is a benefit for immediate angiography after a cardiac arrest, but for now its role remains murky.) I also wonder if there isn’t less obvious harm. This harm is not so much to the patient undergoing a false positive activation, but to our other patients. What is the impact on our Tuesday patients if we are up in the wee hours Monday night unnecessarily caring for a patient with a false positive activation? In most places interventional cardiologists do not account for sleeplessness in creating their schedules. Thus, most do in fact put in full days seeing patients, performing procedures, etc. even after being up most of the night before. We are used to it, but I suspect each of us would agree that research studies and our own personal experiences would argue that we aren’t as sharp when we go without sleep. It is gratifying and even at times exhilarating to care for a patient undergoing primary PCI for an acute myocardial infarction, which provides some counterbalance to the ensuing exhaustion. But it is emotionally draining to be obliged to come in and do an angiogram when no value is being provided other than reassuring people that no-one is missing a true STEMI. Sometimes it cannot be helped — the ECG and clinical presentation fall within the boundaries of guidelines recommending emergent catheterization, but the anatomy fails to live up to expectations — perhaps the clot or spasm have resolved, etc. But at other times, perhaps we are asked to perform an angiogram on someone with an uncompelling story, with abnormal ECGs not meeting guideline recommendations — such as minimal ST elevations in the face of Q waves in someone with non-cardiac symptoms. The reported literature suggests that unremarkable coronary angiograms are seen in ~10-15% of cases in whom a cath lab has been activated for a STEMI, but these reports perhaps do not reflect all hospitals’ experiences. Although there are no data available, it may be that the difference in false positive activations which vary between 10% and 60% is due to differing thresholds for referring these non-guideline recommended cases for emergent caths. If this is the case, then it seems reasonable as a quality assessment measure for hospitals to address how many “unnecessary” cath lab activations occur. This could lead to greater discrimination and perhaps enhance quality, rather than lead to missed STEMI activations, as so many fear would happen with a higher threshold. For this type of rigorous scrutiny to become commonplace will require a willingness to discuss this issue openly — which currently does not seem to be done at many institutions.