Fellow Physician Allegheny General Hospital Mechanicsburg, Pennsylvania, United States
Background: Defibrillators can be tricked by high atrial rates, mistaking them for dangerous arrhythmias like ventricular fibrillation. This can lead to unnecessary shocks, which may trigger actual ventricular fibrillation, escalating the risk of sudden cardiac arrest.
Methods: A multidisciplinary cardiogenic shock team meeting was convened for a 53-year-old male patient who presented after an out-of-hospital cardiac arrest. The patient, with a history of longstanding non-ischemic cardiomyopathy (EF 15-19%), nonobstructive coronary artery disease (CAD), atrial fibrillation, and supraventricular tachycardia (SVT), had been non-adherent to medications. On arrival, he was unresponsive and in the midst of ongoing active chest compressions following the Advanced Cardiac Life Support (ACLS) protocol. Given the clinical scenario and concerns about a potential cardiac etiology, the patient's implantable cardioverter-defibrillator (ICD) was interrogated. The interrogation revealed a device malfunction, which had likely led to the inappropriate shock that initiated the cardiac arrest event. This malfunction was considered to be the primary cause of the arrest. The team, which included cardiologists, intensivists, and electrophysiologists, collaborated to assess the underlying issues and manage the patient's condition effectively. The patient’s history of non-adherence to prescribed medications, coupled with his complex arrhythmias and low ejection fraction, created a high-risk scenario, requiring careful attention to both the mechanical device and underlying cardiac issues. Prompt recognition of the ICD malfunction and the initiation of appropriate management strategies were crucial in stabilizing the patient and guiding further therapeutic decisions.
Outcome: The patient was transferred to the cardiac ICU, where targeted temperature management was initiated. Upon arrival, trauma scans revealed concerns for anoxic brain injury due to unclear downtime. Bedside interrogation of his ICD showed his initial rhythm was supraventricular tachycardia (SVT) with rates exceeding 220, beyond the upper limit of the ICD’s VT1 zone threshold of 200. He experienced an episode of atrial fibrillation with rapid ventricular rates (maximal rate of 220), triggering ATP and multiple episodes of VT. Ultimately, he was shocked by the device and developed ventricular fibrillation. Approximately 9 minutes later, the device reset, shocking him back into an atrial rhythm after prolonged arrest and insufficient cerebral perfusion. Imaging confirmed signs of anoxic brain injury. He was stabilized overnight in the cardiac ICU; however, given the severity of his condition, his family opted for comfort care, and he passed away.
Conclusion: While primary prevention ICDs are essential for patients at high risk of life-threatening arrhythmias, they can also have harmful effects, as demonstrated by this patient's device malfunction and subsequent cardiac arrest. All patients with ICDs should be regularly interrogated to assess device function and identify potential issues.
