PO-01-202 HEART RATE FRAGMENTATION AS A MARKER OF ALTERED ACTIVITY OF THE AUTONOMIC NERVOUS SYSTEM ACTIVITY : A NOVEL PREDICTOR OF ATRIAL FIBRILLATION OCCURRENCE IN THE GENERAL POPULATION

Abstract

The dysfunction of the autonomic nervous system (ANS) plays a crucial role in atrial fibrillation (AF). But the meaning of high heart rate variability (HRV) in predicting AF is still under debate. Short-term HRV is conceptually attributed to physiologic vagal tone modulation. But recent data suggest that a component of short-term HRV, called heart rate fragmentation, is related to ANS breakdown. To assess the predictive capacity of novel short-term HRV-derived metrics regarding the occurrence of AF in the general population during long-term follow-up. A cohort study was designed to prospectively assess the predictive value of ANS activity level regarding cardiovascular events and mortality. 1011 subjects aged 65, without history of AF, and with low cardiovascular risk were enrolled in the study. A 17.8-year follow-up was managed. HRV data were acquired by 24-h Holter ECG monitoring at baseline and assessed by frequency and time-domain methods. Heart rate fragmentation using the percentage of inflection points (PIP) and alpha 1-index (using fractal evaluation of NN intervals) were also calculated. AF occurrence during follow-up was registered and defined as a standard 12-lead ECG recording or Holter recording with ≥ 30 s of AF. AF was diagnosed in 123 patients representing a cumulative incidence of 13.4%. Univariate analyses are presented in the Table. The occurrence of AF was independently predicted by the male gender (HR=1.96,95%CI:1.3-2.9,p<0.01), a higher percentage of NN intervals that differ by more than 50 ms from the previous interval (pnn50) (HR=2.01,95%CI:1.3-3.2,p<0.01), an increased percentage of inflection points (HR=2.48,95%CI:1.5-4.2,p<0.01), and a reduced alpha 1 index (HR=1.63,95%CI:1.04-2.55,p<0.01). Given these results, a predictive score was built up based on the 4 independent predictors (Panel A). A predictive score of AF occurrence during the 18-year follow-up was assigned to every patient from 0 to 4. Compared to the group of patients with a score of 0 (Panel B), AF occurrence was progressively increased in patients with a score of 2 (HR=5.93, 95%CI:0.82-43.08, p=0.08), of 3 (HR=12.75, 95%CI:1.75-92.83, p=0.01), and of 4 (HR=22.31, 95%CI:2.98-167.23, p<0.01). Markers of heart rate fragmentation independently predict the AF occurrence in the general population, such as an increased PIP and a reduced alpha 1-index. A clinical predictive score is able de segregate a population at high risk of AF occurrence among the general population.Tabled 1Univariate analysesVariablesHRCI 95%P-valueCLINICAL FEATURESMale gender1.741.22 - 2.48<0.01Hipertension1.741.22 - 2.50<0.01Overweight1.331.04 - 1.700.02Increased PAC burden2.111.31 - 3.41<0.01ANS FEATURESpnn501.841.28 - 2.64<0.01RMSSD1.901.33 - 2.71<0.01LF/HF0.600.39 - 0.940.02PIP2.201.40 - 3.47<0.01Alpha 12.191.54 - 3.12<0.01Deceleration capacity2.001.30 - 3.09<0.01 Open table in a new tab