Noninvasive arrhythmia risk stratification in idiopathic dilated cardiomyopathy: results of the Marburg Cardiomyopathy Study.
BACKGROUND
Arrhythmia risk stratification with regard to prophylactic implantable cardioverter-defibrillator therapy is a completely unsolved issue in idiopathic dilated cardiomyopathy (IDC).


RESULTS
Arrhythmia risk stratification was performed prospectively in 343 patients with IDC, including analysis of left ventricular (LV) ejection fraction and size by echocardiography, signal-averaged ECG, arrhythmias on Holter ECG, QTc dispersion, heart rate variability, baroreflex sensitivity, and microvolt T-wave alternans. During 52+/-21 months of follow-up, major arrhythmic events, defined as sustained ventricular tachycardia, ventricular fibrillation, or sudden death, occurred in 46 patients (13%). On multivariate analysis, LV ejection fraction was the only significant arrhythmia risk predictor in patients with sinus rhythm, with a relative risk of 2.3 per 10% decrease of ejection fraction (95% CI, 1.5 to 3.3; P=0.0001). Nonsustained ventricular tachycardia on Holter was associated with a trend toward higher arrhythmia risk (RR, 1.7; 95% CI, 0.9 to 3.3; P=0.11), whereas beta-blocker therapy was associated with a trend toward lower arrhythmia risk (RR, 0.6; 95% CI, 0.3 to 1.2; P=0.13). In patients with atrial fibrillation, multivariate Cox analysis also identified LV ejection fraction and absence of beta-blocker therapy as the only significant arrhythmia risk predictors.


CONCLUSIONS
Reduced LV ejection fraction and lack of beta-blocker use are important arrhythmia risk predictors in IDC, whereas signal-averaged ECG, baroreflex sensitivity, heart rate variability, and T-wave alternans do not seem to be helpful for arrhythmia risk stratification. These findings have important implications for the design of future studies evaluating prophylactic implantable cardioverter-defibrillator therapy in IDC.
Grimm
Wolfram
W
Department of Cardiology, Philipps-University Marburg, Baldingerstrasse, 35033 Marburg, Germany. wolfram.grimm@med.uni-marburg.de
Christ
Michael
M
Bach
Jennifer
J
Müller
Hans-Helge
HH
Maisch
Bernhard
B
D000293:Adolescent; D000319:Adrenergic beta-Antagonists / Q000627:therapeutic use; D000328:Adult; D000368:Aged; D000889:Anti-Arrhythmia Agents / Q000627:therapeutic use; D001145:Arrhythmias, Cardiac / Q000453:epidemiology* / Q000209:etiology / Q000517:prevention & control; D001281:Atrial Fibrillation / Q000150:complications; D017704:Baroreflex / Q000187:drug effects; D002311:Cardiomyopathy, Dilated / Q000150:complications* / Q000188:drug therapy; D016757:Death, Sudden, Cardiac / Q000453:epidemiology / Q000209:etiology; D017147:Defibrillators, Implantable; D004554:Electric Countershock; D015716:Electrocardiography, Ambulatory; D005260:Female; D005858:Germany / Q000453:epidemiology; D006339:Heart Rate; D006801:Humans; D015993:Life Tables; D008297:Male; D008875:Middle Aged; D010656:Phenylephrine; D016016:Proportional Hazards Models; D011446:Prospective Studies; D012306:Risk; D013318:Stroke Volume; D016019:Survival Analysis; D017180:Tachycardia, Ventricular / Q000453:epidemiology / Q000209:etiology; D014693:Ventricular Fibrillation / Q000453:epidemiology / Q000209:etiology
D000319:Adrenergic beta-Antagonists; D000889:Anti-Arrhythmia Agents; D010656:Phenylephrine