In the communication by Nascimento et al published in the February 1, 2014 issue of The American Journal of Cardiology , the authors propose a new diagnostic index, consisting of the product of peak troponin I value and the left ventricular ejection fraction, acutely assessed by echocardiography (troponin–ejection fraction product), for the differentiation between Takotsubo syndrome (TTS) and acute ST elevation myocardial infarction (STEMI). Receiver operating characteristic curve analysis revealed that a troponin–ejection fraction product value of ≥250 had a sensitivity of 95%, a specificity of 87%, a negative predictive value of 94%, a positive predictive value of 88%, and an overall accuracy of 91% to differentiate an STEMI from TTS. Others with the same motivation have implemented the ratio of peak N-terminal prohormone of brain natriuretic peptide to troponin T and found that a cut-off value of 2,889 distinguished TTC from STEMI, with a sensitivity of 91% and a specificity of 95%. It would have been of great interest to have head-to-head comparisons of these 2 indexes in the same population, but the retrospective study of Nascimento et al did not include sampling for N-terminal prohormone of brain natriuretic peptide. A new electrocardiographic index has also been recently described based on the observation of attenuated amplitude of QRS complexes, either on the admission electrocardiogram (ECG) or in the comparison of the admission ECG with the second such tracing recorded. There is a marvelous opportunity to compare the 2 initial ECGs in terms of the amplitude of the QRS complexes in the 59 patients with TTS and the 60 patients with an STEMI of the study of Nascimento et al. If the authors have some patients in their TTS and STEMI subgroups who had a previous available ECG, recorded before presentation with TTS and STEMI, comparison of the admission ECGs with the corresponding previous electrocardiographic tracings may provide further insight. As we strive to discover the best diagnostic index for the differentiation between TTS and STEMI, head-to-head comparisons of various indexes will be required. The authors were careful not to imply that coronary arteriography is not needed for the definitive differentiation between TTS and STEMI, but they suggested that for very sick patients, those with multiple noncardiac co-morbidities, or for any other patients for whom emergent coronary arteriography may not be needed or can be delayed, the troponin–ejection fraction product may have a role. Of course, the Holy Grail TTS/STEMI differentiation index would be the one applied to all comers indiscriminately, obviating coronary arteriography up front, for patients who subsequently are found to have TTS.