Prevalence, characteristics and natural course of inappropriate sinus tachycardia

Aims To study the prevalence, characteristics and natural course of inappropriate sinus tachycardia (IST). Methods and results The prevalence and characteristics of IST were evaluated in a random sample of 604 middle-aged subjects. Seven of the subjects (1.16%) fulfilled the contemporary diagnostic criteria of IST. The systolic (147 +/- 11 mmHg vs. 130 +/- 13 mmHg, P < 0.001) and diastolic ambulatory blood pressures (92 +/- 7 mmHg vs. 81 +/- 8 mmHg, P < 0.001) were higher among the subjects with IST than among the controls. The other laboratory, echocardiographic and personality measurements, with the exception of the hostility score (10 +/- 2 vs. 8 +/- 3, P < 0.001), revealed no differences between the groups. The natural course and prognosis of the disorder was assessed among the subjects fulfilling the IST criteria and nine previously diagnosed IST patients. During a mean follow-up of 6.0 +/- 2.4 years, none of the subjects developed any clinical or echocardiographic evidence of structural heart disease despite ongoing palpitations, and there was no significant reduction in the 24-h average HR (94 +/- 2 bpm vs. 89 +/- 8 bpm, P = 0.204). Conclusion The prevalence of IST in a middle-aged population was higher than previously assumed. Despite the chronic nature of the disorder, the prognosis of IST was benign. The causal relationship between IST and hypertension and/or hostile personality type remains speculative. (c) 2005 The European Society of Cardiology. Published by Elsevier Ltd. All rights reserved.