[Prevention of sudden death in heart failure patients: cardiac resynchronization therapy with or without defibrillation back-up]. / Prevenzione della morte improvvisa nel paziente con insufficienza cardiaca: terapia di resincronizzazione cardiaca con o senza back-up di defibrillazione.

The prevalence and incidence of heart failure are progressively increasing in both Europe and the United States. Despite many advances in diagnosis and therapy, morbidity and mortality remain high and long-term prognosis is still poor in most heart failure patients. The use of implantable devices, cardiac resynchronization therapy and implantable cardioverter-defibrillators plays a pivotal role in the treatment of heart failure. Cardiac resynchronization therapy improves survival and reduces cardiac mortality due to either sudden or non-sudden death. In clinical practice, patients with an indication for cardiac resynchronization therapy should be carefully evaluated in view of a potential concomitant indication for defibrillator implantation. The combination of the two therapies may have maximal beneficial effects on prognosis.

[Risk stratification for sudden cardiac death: from the electrophysiological study to T-wave alternans]. / Stratificazione del rischio di morte improvvisa: dallo studio elettrofisiologico all'alternanza dell'onda T.

T-wave alternans is a change, in the microvolt range, of T-wave amplitude on an ABABAB sequence. At present, various groups of patients have been evaluated, including those with myocardial infarction, congestive heart failure, implantable cardioverter-defibrillators and a clinical indication for programmed ventricular stimulation. In all clinical conditions analyzed, T-wave alternans analysis demonstrated a good diagnostic accuracy, suggesting a possible clinical use of the test in these settings.

T wave alternans is a predictor of death in patients with congestive heart failure.

Few data are available about the prognostic role of T wave alternans in patients with congestive heart failure. To assess the ability of T wave alternans, used alone or in combination with other risk markers, to predict cardiac death in decompensated patients, we enrolled 46 patients, mean age 59+/-9, males 89%, ischemic etiology 61%, NYHA class III 35%, left ventricular ejection fraction 29+/-7%. After 1.6 years follow-up, seven patients died from cardiac death (16%), non-sudden in six (86%) and sudden in one (14%). T wave alternans was positive in 24 (52%), negative in 13 (28%), indeterminate in nine patients (20%). T wave alternans was positive in all patients with events (100%) but only in 16 of 37 patients without (41%) (P=0.02). Other predictors of cardiac death were O(2) consumption at the peak of exercise (P=0.03), standard deviation of all NN intervals (P=0.05) and Wedge pressure (P=0.03). When receiver operator characteristics curves were calculated, the highest area (0.73) was found for O(2) consumption at the peak of exercise considering the single variables and for O(2) consumption at the peak of exercise plus T wave alternans (0.79) for combination of them; the comparison of the two receiver operator characteristics curves did not reach statistical difference (P=0.5). In conclusion, this is the first study reporting that T wave alternans can predict cardiac death, with a marginal additional prognostic power when used in combination with measurement of O(2) consumption at the peak of exercise.

[T-wave alternation: a new method for identifying patients at risk of malignant ventricular tachyarrhythmia]. / L'alternanza dell'onda T: un nuovo metodo per individuare i pazienti a rischio di tachiaritmie ventricolari maligne.

T wave alternans (TWA) is a change, in the microvolt range, of T wave amplitude on ABABAB sequence. TWA depends on heart rate, being optimally analyzed at a target frequency of 110 b/min. Initial studies used atrial pacing to reach the target frequency and reported a sensitivity and specificity of 89% for TWA in predicting tachyarrhythmic events. Subsequently, similar results were obtained using ergometric test to reach the target frequency, a less invasive and more "physiologic" approach to increase heart rate. This method became therefore the elective system to increase heart rate in order to evaluate the presence of TWA by means of spectral analysis. At present, various groups of high arrhythmic risk patients have been evaluated, including those with a recent myocardial infarction, congestive heart failure, implantable cardiac defibrillator and clinical indication to programmed ventricular stimulation. In all clinical conditions analyzed, TWA analysis demonstrated a good diagnostic accuracy, suggesting a possible clinical use of the test in these settings.