• Winker, Robert
• Robertson, David
• Pezawas, Thomas
• Diedrich, André
• Wang, Li
• Richter, Bernhard
• Byrne, Daniel W.
• Schmidinger, Herwig

Abstract

<jats:sec><jats:title>Background—</jats:title><jats:p>Prophylactic defibrillator implantation is recommended in dilated, nonischemic heart disease and left ventricular ejection fraction of ≤0.30 to 0.35. Noninvasive testing should improve accuracy in decision making of prophylactic defibrillator implantation.</jats:p></jats:sec><jats:sec><jats:title>Methods and Results—</jats:title><jats:p>We enrolled 60 patients (median age, 57 years) with dilated cardiomyopathy and left ventricular ejection fraction ≤0.50, and 30 control subjects (median age, 59 years) with left ventricular ejection fraction &gt;0.50. The protocol included an initial assessment, a second assessment after 3 years, and a final follow-up: pharmacological baroreflex testing (baroreceptor reflex sensitivity), short-term spectral analysis of heart rate variability (low frequency/high frequency), and long-term time domain analysis (SD of all normal-to-normal R–R intervals), exercise microvolt T wave alternans, and signal-averaged ECG, and corrected QT-time. The median follow-up was 7 years. End points were cardiac death, resuscitated cardiac arrest, and arrhythmic death. Cardiac death was observed in 21 patients. Resuscitated cardiac arrest and arrhythmic death caused by ventricular tachyarrhythmias ≥240 per minute was observed in 7 and 10 patients, respectively. In the single time point analysis, microvolt T wave alternans, baroreceptor reflex sensitivity, and SD of all normal-to-normal R–R intervals at initial testing added significant information regarding cardiac death. Microvolt T wave alternans added information on resuscitated cardiac arrest or arrhythmic death at multiple time points (<jats:italic>P</jats:italic>&lt;0.001). False-negative microvolt T wave alternans results were seen in 8% of patients.</jats:p></jats:sec><jats:sec><jats:title>Conclusions—</jats:title><jats:p>Noninvasive testing and left ventricular ejection fraction could not reliably identify patients with dilated cardiomyopathy at risk of fatal ventricular tachyarrhythmias. Therefore, the strategy to confine prophylactic implantable cardioverter-defibrillator implantation to patients with dilated cardiomyopathy and severely reduced LV function should be reconsidered.</jats:p></jats:sec>

Topics

• impedance spectroscopy
• size-exclusion chromatography