A case of bad timing: Inappropriate implantable cardioverter defibrillator therapy due to a critically placed premature ventricular contraction

A 58-year-old man with an ischemic cardiomyopathy underwent ICD implantation after having an electrophysiological study positive for inducible, sustained monomorphic VT. Approximately 1 week later he experienced a shock. Inspection of stored electrograms revealed that a run of nonsustained VT had initiated his ICD to charge. The episode spontaneously terminated, yet the shock was still delivered during sinus rhythm. Further inspection revealed that a critically timed PVC during the "second look" interval resulted in delivered therapy. Thus, inappropriate ICD therapy can result from causes other than SVT, lead malfunction, or over sensing.