Natural history of cardiac arrest in patients with takotsubo cardiomyopathy.

Cardiac arrest (CA) is relatively rare but lethal complication of takotsubo cardiomyopathy (TTC). In most instances, patients are diagnosed with TTC after CA, making it difficult to distinguish if TTC is the precipitant or the consequence of the index event. In this systematic review, patient-level data were obtained to seek out the characteristics of patients in whom the underlying cause of CA is TTC. A comprehensive search of 4 major databases (Embase, Ovid MEDLINE, PubMed, and Google Scholar) was performed from their inception to the last week of September 2014. Of 186 citations, 62 case studies were included in the analysis, providing patient-level data on 77 patients. In 60 patients (78%), the diagnosis of TTC was made after CA. Patients presenting with CA were younger (mean age 49.5 ± 16 vs 64.9 ± 11 years, p <0.0001) and had relatively shorter corrected QT interval (mean 530 ± 101 vs 616 ± 140 ms) on electrocardiography. TTC-related hypotension was the major cause of CA in the acute phase, while a long corrected QT interval triggered CA in the subacute (24- to 72-hour) phase. In 11 patients, CA was not directly instigated by TTC despite a left ventricular appearance matching TTC. In conclusion, in TTC, CA typically develops within the first 3 days of presentation and is the result of long corrected QT interval-induced polymorphic ventricular tachycardia. Secondary TTC, in which patients present with typical left ventricular features after CA, likely represents a distinct cohort in which identifiable inheritable arrhythmias or structural heart disease should be sought.