Abstract 10880: Impact of Post-Extrasystolic Potentiation on Takotsubo Cardiomyopathy

Abstract

Introduction: Takotsubo cardiomyopathy (TCM) is an increasingly recognized condition that presents with transient and reversible left ventricular (LV) dysfunction despite angiographically unobstructed coronary arteries. However the detailed pathophysiology of the stunned myocardium remains to be determined. Post-extrasystolic potentiation (PESP) is an increase in contractility after an extrasystole, thought at least in part due to a net increase in myocardial calcium. When PESP occurs in akinetic LV segments, it is a marker of myocardial viability. Obviously the myocardium in TCM is viable, thus we hypothesized that the affected myocardium in TCM would demonstrate PESP. Methods: We retrospectively reviewed 61 cases of TCM diagnosed by the Mayo criteria between the periods of October 2004 to May 2015. The 24 cases wherein left ventriculography fortuitously provoked extra systoles (PVCs) were evaluated. Results: In our study, the baseline characteristics of TCM were 93.4% female patients with mean age of 67. Mean ejection fraction was 38% and mean troponin I elevation was 5.5. Apical type was the predominant (72.1%) compared to the mid-ventricular type (23.0%). None of the 24 patients in whom ventriculographic PVCs occurred demonstrated PESP in the affected region of the LV, while all did in the unaffected portion. Conclusions: Extra-systoles in TCM fail to elicit PESP in affected LV segments despite proven viability in those segments while unaffected segments behave as predicted. Since increased calcium is thought to be the basis for PESP, it is possible in TCM that either there is failure of calcium release in the affected areas or that the presumed catecholamine excess of TCM has already caused maximum calcium release so PCVs cannot enhance contractility further.