Background: Although symptoms can be of some help in identifying the arrhythmia related to implantable cardioverter-defibrillator (ICD) discharge, symptomatic supraventricular arrhythmias and asymptomatic ventricular tachycardia have been reported.
Methods: In 18 survivors of cardiac arrest implanted with an ICD, the symptoms and intracardiac electrograms were systematically evaluated, in order to better define a relationship between some symptoms and supraventricular or ventricular tachyarrhythmias.
Results: A total number of 249 arrhythmic episodes were detected by the ICD during a mean follow-up of 378 +/- 107 days (range 137 to 642). Within this time, in 15 out of 18 patients (83%) at least one arrhythmic event alerting the device occurred, determining a therapeutic attempt in 13 patients. Only 49% of the episode stored by the ICD were symptomatic. Symptoms like palpitations, dizziness, "going under" lacked of predictability for ventricular tachycardia; in contrast, patients describing a "hot flush", alone or associated with palpitations, lightheadedness, dizziness most commonly recognized a ventricular tachyarrhythmias. This symptom had a good sensitivity (72%) and a high specificity (95%) in detecting a sustained ventricular tachycardia.
Conclusions: Since in most cases symptoms are not a reliable criterion for validating ICD discharges stored electrograms during ICD activation need to be considered for analysis. However, the data of this study showed the importance of "hot flush" as a key symptom for recognizing the occurrence of a sustained ventricular tachyarrhythmia.