Methodological Issues and Their Impact on Conclusions

The study by Weil et al. used pressure-volume (PV) analysis to compare hemodynamic effects of 2 different percutaneous mechanical circulatory support (MCS) strategies: a transvalvular pump (Impella CP, ICP]) and a left atrial-to-femoral artery bypass pump (TandemHeart [TH]) in an animalmodel of postmyocardial infarction left ventricular (LV) dysfunction. We have written extensively on the theories of this topic, which are supported by both preclinical studies and previously described simulation of the cardiovascular system. Weil and colleagues identify apparent discrepancies between their experimental findings and theoretical predictions. In an accompanying editorial, Kern and Seto encourage efforts directed at resolving those discrepancies. We noted several methodological issues not addressed during the review of the paper that may invalidate several of the findings. Only the most overt issues can be discussed in this brief letter, though a more thorough critique has been shared with the authors. …