Inappropriate Sinus Tachycardia in a Patient with Gilles de la Tourette Syndrome: A Case Report

Background: Inappropriate sinus tachycardia (IST) is characterised by persistent sinus tachycardia without an identifiable secondary cause, whereas Gilles de la Tourette syndrome (GTS) is a neurodevelopmental tic disorder. Although autonomic disturbances have been discussed in relation to both conditions, their clinical coexistence remains poorly characterised. Case presentation: A 31-year-old woman diagnosed with GTS at the age of 13 years and with well-controlled asthma presented with dyspnoea during an asthma exacerbation and a heart rate of 140–150 beats/min. Persistent tachycardia of 100–140 beats/min had been present for more than six months before this episode. Tachycardia continued after respiratory symptoms improved and salbutamol was stopped. Laboratory investigations did not identify anaemia, thyroid dysfunction, electrolyte disturbance or evidence of myocardial injury. Pulmonary embolism was considered unlikely following clinical assessment and D-dimer testing. Orthostatic assessment did not support postural tachycardia syndrome, and telemetry confirmed persistent sinus tachycardia. Echocardiography showed a left ventricular ejection fraction of 68.3%. Ivabradine at 7.5 mg twice daily was ineffective. Bisoprolol, increased from 2.5 to 5 mg daily, was tolerated despite asthma and produced clinical improvement. At one month, Holter monitoring showed a mean heart rate of 94 beats/min. Conclusion: This case documents the coexistence of GTS and IST without establishing causation. The maternal history of tachycardia raises an unconfirmed possibility of familial susceptibility. Careful assessment of secondary causes and individualised treatment remain important.