Chronic inappropriate sinus tachycardia in elderly females

The vast majority of reports of inappropriate sinus tachycardia (IST) had included predominantly young females with ages ranging between 15 and 46 years. In contrast, the present study presents the findings in four elderly females (aged 61-71 years) with long-standing symptoms of palpitations, more than 15 years, in whom IST was diagnosed in their 6th or 7th decade.

Clinical and laboratory examinations including electrocardiograms, echocardiograms, and heart rate variability studies were retrospectively reviewed in four of the nine elderly female patients with long-standing cardiac symptoms. Indices of heart rate variability were compared to four age-matched asymptomatic elderly females with no structural heart disease.

The resting electrocardiograms were normal but one had voltage criteria for left ventricular hypertrophy. All traditional time- and frequency-domain indices were significantly decreased in the symptomatic elderly females as compared to the controls. Echocardiograms showed normal ejection fraction, and in three patients evidence of diastolic dysfunction and mild left ventricular hypertrophy. Blood pressures were elevated, with systolic blood pressure ranging from 170 to 190 and diastolic blood pressure ranging from 94 to 106. Anxiety disorders were diagnosed in all patients.

This study demonstrates that IST can be present in a wide spectrum of patient populations, including elderly populations. It seems that some cases of IST can become chronic if not treated adequately. Apparently, earlier identification and treatment could have improved the quality of life of the patients. Traditional HRV indices may not be valuable to support either a sympathetic or parasympathetic mechanism. Therefore, further studies should consider the potential usefulness of the nonlinear method such as, for example, approximate entropy and detrended fluctuation analysis.