BAROREFLEX SENSITIVITY AND HEART-RATE-VARIABILITY IN CORONARY-DISEASECOMPARED TO DILATED CARDIOMYOPATHY

This study was designed to compare baroreceptor sensitivity and heart rate variability as measures of cardiac autonomic tone in patients wit h coronary disease (CAD, n = 49) and idiopathic dilated cardiomyopathy (IDC, n = 130). Time domain heart rate variability, including SDNN, S DANN, and pNN50, was determined during 24-hour Holter EGG. Baroreflex sensitivity was analyzed nonivasively using the phenylephrine method. Baroreflex sensitivity and heart rate variability were comparable betw een patients with CAD versus IDC (baroreflex sensitivity: 6.1 +/- 3 vs 6.9 +/- 5 ms/mmHg; SDNN: 97 +/- 40 vs 114 +/- 41 ms; SDANN: 83 +/- 33 vs 99 +/- 41 ms; pNN50: 3.9 +/- 4 vs 9.6 +/- 13 ms, P = NS for all co mparisons). Likewise, a subgroup analysis of patients with a left vent ricular ejection fraction (LVEF) less than or equal to 30% showed no s ignificant difference in baroreceptor sensitivity and heart rate varia bility between IDC and CAD patients. Patients with CAD and an LVEF > 3 0% had a decreased heart rate variability but not a decreased barorefl ex sensitivity compared to patients with IDC and LVEF > 30 % (barorefl ex sensitivity: 6.4 +/- 4 vs 8.3 +/- 6 ms/mmHg, P = NS; SDNN: 98 +/- 1 9 vs 128 +/- 42 ms, P < 0.05; SDANN: 86 +/- 21 vs 112 +/- 43 ms, P < 0 .05; pNN50: 4.2 +/- 3 vs 12.3 +/- 8 ms, P < 0.05). Patients with a mar kedly depressed LVEF show comparable alterations in cardiac autonomic tone whether they have CAD or IDC. Patients with CAD and preserved LV function, however, have a decreased heart rate variability compared to patients with LDC and preserved LV function. The prognostic significa nce of these findings will be determined prospectively in a large pati ent cohort at our institution.