Heart Rate Variability in a Cohort of Hypertensive Patients - A Closer Look at RMSSD

Objective: Heart rate variability (HRV) is a measure of the autonomic regulation of the heart and is predictive for sudden cardiac death. rMSSD is an HRV parameter equal to the square root of the sum of all differences between successive R-R intervals and is indicative of parasympathetic activity. Design and method: A retrospective study was performed on 69 hypertensive patients admitted to our clinic during a two year period. Data collected included patient demographics, history, comorbidities and treatment; moreover, laboratory assays, echocardiography and 24-Hour Holter monitoring information were made available for all patients. Patients in whom laboratory assays or echocardiographic data were unavailable and those with very low quality of the 24-hour electrocardiographic monitoring were excluded. Data analysis was performed using IBM SPSS, version 20 in order to obtain descriptive and inferential statistics. Results: Out of the 69 patients, 68.10% were women, while 31.90% were men, with a mean age of 68.92 ± 9.91 years. All patients had arterial hypertension either grade 2 (27.50%) or grade 3 (72.50%) and underwent treatment with either ACEi/ARB, CCB, diuretic or a combination thereof. Most patients (77.20%) had left atrial enlargement with a mean volume of 73.32 ± 33.19 ml, though only 29% of patients had been previously diagnosed with atrial fibrillation. rMSSD (50.18 ± 33.30) correlated with age (p < 0.001), left atrial volume (p = 0.001), lateral wall MAPSE (13.14 ± 2.64 mm, p = 0.006), hemoglobin levels (13.17 ± 2.06 g/dl, p = 0.016) and mitral regurgitation severity (p < 0.01). Conclusions: The current study shows a high rMSSD in hypertensive patients in spite of antihypertensive treatment. Furthermore, since left atrial enlargement and age are both risk factors for atrial fibrillation, rMSSD may also be a sign that patients are prone to develop atrial fibrillation.