Tachycardia during coronary computed tomography angiography.

A 76-year-old woman underwent a coronary artery computed tomography angiography (CTA) to exclude coronary occlusive disease after a segmental inferoseptal hypokinesia was discovered at echocardiography in the workup for atypical chest pain. The patient has a body mass index of 40 kg/m2, a history of arterial hypertension, hyperlipidemia, hypothyroidism, and type 2 diabetes. Her drug regimen consists of acenocoumarol, bisoprolol, potassium canrenoate, simvastatin, levothyroxine, and metformin. She also has a history of a second-degree type I atrioventricular block found 18 years earlier during an episode of atrial fibrillation (AF) that has led to several syncopes. A Topaz II pacemaker (Vitatron, Maastricht, the Netherlands) was implanted 10 years ago, replaced 1 year ago, with preservation of the lead, by a Zephyr SR 5620 pacemaker (St. Jude Medical, St. Paul, MN, USA) in the ventricular rate modulated pacing (VVIR mode). The pacemaker control examinations 10 days prior and 6 months after CTA showed a normally functioning stimulator with a virtually permanent ventricular pacing and no alert between both examinations. Stimulation (0.75 then 0.75 V) and sensing (9.6 then 9.3 mV) thresholds and lead impedance (827 then 848 ohms) were within normal ranges and relatively unchanged between both examinations. The activity sensor was turned “on” and the maximum sensor rate was set at 130 beats per minute (bpm). Reaction time was tuned to “fast” and recovery time to “medium.” Stimulation was programmed in the unipolar mode and sensing in the bipolar mode. Battery voltage was 2.79 V with an estimated remaining life of more than 7 years. The 64-row multidetector LightSpeed VCT XT scanner (General Electric, Fairfield, CT, USA)