Heart rate variability and heart rate recovery in patients with coronary artery ectasia

Background Coronary artery ectasia (CAE) is characterized by an abnormal dilatation of the coronary arteries, which is a variant of coronary artery disease (CAD). Increased sympathetic activity or decreased vagal modulation of cardiac function assessed by heart rate variability (HRV) analysis has been associated with an increased risk of coronary artery disease and mortality and angiographic progression of coronary atherosclerosis, as well as arrhythmia and sudden cardiac death. Heart rate recovery index is a strong indicator of risk in asymptomatic and symptomatic CAD. To the best of our knowledge, no study has been conducted to investigate the relationship between HRV, heart rate recovery, and CAE. The purpose of this study was to examine the changes in heart rate recovery and HRV measurements in coronary artery ectasia. Methods The study population consisted of 50 consecutive patients (24 women; mean age 46 +/- 5 years) with CAE, and 35 asymptomatic healthy individuals comprised the control group (19 women; mean age 44 +/- 7 years). We performed electrocardiography, echocardiography, Holter analysis, exercise stress test, routine biochemical tests and evaluated the clinical characteristics. Time-domain parameters of HRV (mean R-R intervals; standard deviations of all N-N intervals; standard deviations of the averages of N-N intervals), the root mean square of the difference in successive R-R intervals, proportion derived by dividing the number of interval differences of successive N-N intervals greater than 50 ms by the total number of N-N intervals (pNN50) were evaluated. Heart rate recovery was defined as the difference in the heart rate from peak exercise to 1 min after peak exercise. Results Standard deviations of all N-N intervals (123.7 +/- 30.3 vs. 178.8 +/- 52.7, P<0.001), standard deviations of the averages of N-N intervals (95.2 +/- 27.1 vs. 120.2 +/- 39.6, P=0.001), total number of N-N intervals (11.9 +/- 8.6 vs. 17.1 +/- 6.4, P=0.004) were significantly lower in the CAE group than in healthy controls. The root mean square of the difference in successive R-R intervals was lower in CAE patients than controls, but the differences between groups were not statistically significant (47.5 +/- 23.1 vs. 56.2 +/- 23.6, P = 0.097). The heart rate recovery values measured during the recovery phase were significantly lower in the CAE group compared with the control group (21.3 +/- 11.1 vs. 29.3 +/- 11.9, P=0.002). The incidence of abnormal heart rate recovery [22 (44%) vs. 5 (14%), P=0.002] was greater in patients with CAE group than in controls. Conclusion The results of this study showed that time-domain HRV parameters and heart rate recovery were reduced in patients with CAE. Coron Artery Dis 21:8-12 (C) 2010 Wolters Kluwer Health vertical bar Lippincott Williams & Wilkins.