Reply to the letter regarding the article "Incidence, determinants and prognostic relevance of cardiogenic shock in Takotsubo cardiomyopathy"

We thank Prof. Madias for his interest in our work regarding cardiogenic shock (CS) in patients with Takotsubo cardiomyopathy (TTC). He notes the high prevalence of cardiovascular risk factors in our TTC population, particularly hypertension and diabetes mellitus.1 Hypertension has been reported in >50% of TTC patients repeatedly, and the largest registry found a prevalence of 65%.2,3 However, the number of patients with diabetes mellitus (28.1%) is indeed higher than in previous studies, even though the reported data show large variations (1.6–25.5%).1,2 Actually, the rate in our population is perfectly in line with the expected prevalence of diabetes mellitus in the general population aged >65 years.4 Unfortunately, we cannot provide additional data regarding drug therapy, glycemic control or associated comorbidities that might have had an impact on outcome. Nevertheless, a potential protective effect of diabetes mellitus in TTC patients is speculative, since the causative mechanisms of the disease have not been elucidated yet and data supporting a favorable prognosis in diabetic TTC patients are not available. Moreover, Prof. Madias addresses the continuing increased risk of death in TTC patients with CS beyond the acute phase. The mortality curve (Figure 1) indicates that most of these deaths occurred between 28 days and 6 months after hospital admission, when left ventricular function had already significantly improved but not yet fully recovered in all patients.1 Despite normalization of systolic function, three patients died after the 6-month period from cardiac arrest, stroke and unknown cause of death, respectively. We think that an ongoing susceptibility to arrhythmias contributes considerably to fatal events during the convalescent phase of TTC.5 Deterioration of left ventricular function after initial recovery has not been observed. However, the cohort of CS patients who survived the first year after the initial event is small, and long-term echocardiographic data are not available in all patients. Early mechanical circulatory support in TTC patients with CS is definitely a reasonable approach considering the assumed pathophysiological mechanisms. Nevertheless, a potential survival benefit has to be proven in randomized controlled trials before assist devices can be recommended as a first-line therapeutic strategy. Finally, Prof. Madias addresses the increase in vagal tone that has been observed in TTC patients. The heart rate and blood pressure values that have been observed in our cohort of patients with TTC and CS are probably influenced by the administration of catecholamines and other agents prior to admission at our institution. Therefore, these values may be indicative but not appropriate to confirm the concept of vagotonia in the early phase of TTC.