Incidence, mechanisms, and clinical impact of inappropriate shocks in patients with a subcutaneous defibrillator.

AIMS: Inappropriate shocks (IAS) remain a challenge for patients and physicians after implantation of the subcutaneous implantable cardioverter-defibrillator (S-ICD). The aims were to assess and characterize different patterns of IAS. METHODS AND RESULTS: Two hundred and thirty-nine patients were implanted with an S-ICD between 2010 and 2018 for primary and secondary prevention. Follow-up data of at least 6 months were analysed. During a mean follow-up of 34.9 ± 16.0 months, a total of 73 shocks occurred in 38 patients (6%). Forty-three (59%) shocks were considered appropriate due to ventricular tachycardia/ventricular fibrillation, while 30 (41%) were inappropriate and occurred in 19 patients (8%). Myopotentials/noise was the most frequent cause of inappropriate shocks (n = 8), followed by T-wave oversensing (n = 6) and undersensing of the QRS, resulting in adaptation of the automatic gain control and inappropriate shock (n = 5). Seventy-four percent of all IAS occurred on the primary vector, while no IAS occurred on the alternate vector. In seven of eight patients (88%), IAS related to myopotentials have occurred on the primary sensing vector. Multivariate analysis identified taller patients, primary sensing vector and first-generation S-ICD device as predictors for IAS. SMART pass effectively reduced the occurrence of IAS in the second-generation S-ICD system. CONCLUSION: Inappropriate therapies are less frequently observed on the alternate vector. The primary vector seems to be unfavourable with regard to oversensing caused by myopotentials. Inappropriate shocks were associated with an increased rate of rehospitalization but not mortality. These observations have implications for the prevention of inappropriate S-ICD shocks.

Takotsubo cardiomyopathy after systemic consolidation therapy with high-dose intravenous cytarabine in a patient with acute myeloid leukemia.

BACKGROUND: Takotsubo cardiomyopathy (TC) is characterized by the abrupt onset of cardiac dysfunction, with transient apical and midventricular hypo-/akinesia with a compensatory hypercontractility of the remaining segments. The clinical presentation appears to be similar to acute myocardial infarction (AMI). However, the myocardial dysfunction is reversible. CASE REPORT: We report on the case of a 58-year-old man with acute myeloid leukemia (AML) who was admitted to our hospital to receive the second course of consolidation chemotherapy with intravenous cytarabine. Subsequently, the patient developed severe dyspnea at rest, with cardiogenic shock after the central venous catheter was removed. Echocardiography revealed severe dyskinesia of the mid and apical portions of both ventricles, accompanied by a highly reduced left ventricular function (LVF). 5 months later, 12-lead electrocardiography (ECG) did not show any evidence of repolar-ization disorders and echocardiographic evaluation revealed a normal LVF. We suppose that the underlying mechanism was TC. CONCLUSIONS: TC can occur in patients with AML under systemic chemotherapy, which possibly represents a triggering factor for TC development. Cardiogenic shock is a serious life-threatening complication of TC. Nevertheless, the prognosis of TC is favorable and a complete recovery of the LVF is possible.