Re: "Reliability of an ECG algorithm for identification of the infarct-related artery in inferior myocardial infarction in clinical practice" by Buchmann et al. Cardiovasc Med. 2022;25:w10119.
As a regular user of the ECG algorithm for the determination of the infarct-causing coronary artery in inferior infarction, I have read your publication with great interest. But I would like to contradict your conclusion that, due to the suboptimal diagnostic reliability and the lack of therapeutic consequences, the use of the algorithm in clinical routine is not advisable – not only because of my own experience to the contrary, but also because of the following argumentation:
The authors argue that in case of an inferior ST-segment elevation myocardial infarction (STEMI) reperfusion therapy as fast as possible should be aimed at anyway, regardless of whether the right coronary artery (RCA) or the circumflex artery is the culprit artery, which is undoubtedly correct. From the point of view of a hospital with direct access to a catheter laboratory, this may suffice as an argument that the algorithm under discussion has no decisive clinical consequences. But the discussion is different for external referrers, especially primary care physicians, emergency physicians in peripheral hospitals, at REGA or in ambulances. They have to assess their myocardial infarction patients locally with regard to their overall risk, start primary therapy and, if necessary, stabilise them haemodynamically and transport them to the catheter laboratory. For the management of these patients, there are prognostic and therapeutic consequences, whether or not there is a high probability of right ventricular infarction. However, the authors do not address this crucial question at all, because they did not apply the criticised algorithm in the original version proposed by Zimetbaum et al. [1]. Specifically, the second step, with implementation of the lead V4right, is missing. If the criteria of this second step are met (ST elevation >0.1 mV in V4r with upright T-wave), according to Zimetbaum [1] and other publications (e.g., autopsy study by Lopez-Sendon et al. in 1985 [2]), the presence of proximal RCA occlusion with consecutive right ventricular infarction can be assumed with high diagnostic reliability (sensitivity 100%; positive predictive value 100%; negative predictive value 88–100%). And this has direct prognostic (significantly higher risk of cardiogenic shock) and therapeutic implications (e.g., preload lowering by nitrate administration should be avoided and cautious volume administration is indicated in the case of hypotension). I have repeatedly experienced such situations in my many years of work as cardiologist and head physician of a peripherally located regional hospital and have found the conclusion from the aforementioned (complete) algorithm to be correct in the vast majority of cases and therefore clinically very helpful. I will continue to use this algorithm and keep it as a useful, quick and inexpensive diagnostic method (simple change of V4 lead to V4 right position) as an internal guideline for inferior infarction.
Finally, the following questions to the authors:
Why was the algorithm not implemented and studied in the original version? Is the reason that at the Kantonsspital Graubüden the additional V4 right lead recommended by the ESC Guidelines 2018 [3] in inferior STEMI is not routinely applied?
What is the reason that this retrospective analysis was performed from 2006 to only 2013, 9 years before the current study publication?
