Hyperglycemia-Induced T-Wave Oversensing as a Cause of Cardiac Resynchronization Therapy (CRT) Failure

T-wave oversensing occurs when the counter starts giving dual beeps for every cardiac cycle instead of one. this usually happens when the monitoring lead displays a tall t wave, which is also sharp. r wave sensing algorithms of the devices do not sense t wave because the slow rate of the t wave is much less than that of the r wave. but the slow rate of t waves may change with time and also because of parameters like potassium levels and hyperglycemia. we present a 67-year-old female who underwent the implantation of cardiac resynchronization therapy (cardiac resynchronization and implantable cardioverter defibrilator [crt-d]) because of severe left ventricular systolic dysfunction and ventricular dyssynchrony experienced recurrent inappropriate implantable cardioverter-defibrillator (icd) shocks and crt failure. device analysis showed that the crt failure was in consequence of t-wave oversensing due to hyperglycemia. elimination of the t-wave oversensing after hyperglycemia control conferred good biventricular pacing and good response to crt during a 6-month follow-up period