Ottorino Costantini

Intracardiac alternans compared to surface T-wave alternans as a predictor of ventricular arrhythmias in humans

BACKGROUND Microvolt T-wave alternans (MTWA) measured from the surface electrocardiogram (ECG) is a marker of sudden cardiac death (SCD). Recently, it has been suggested that intracardiac alternans (ICA) detected from the endocardium underlies MTWA and is a marker of electrical instability leading to ventricular arrhythmias. As such, ICA may be used in future implantable cardioverter-defibrillators (ICDs) to monitor periods of electrical instability before ICD therapy. We examined whether electrical instability, as measured by MTWA, can be detected by ICA located from the right ventricle and if ICA can predict ventricular arrhythmias in patients with ICDs. METHODS Both MTWA and ICA were measured simultaneously during atrial pacing in 68 patients undergoing electrophysiology study (EPS). ICA was measured from unipolar electrograms acquired from a catheter at the apical, mid, and basal regions of the right ventricle in 48 patients and at the apical region alone in 20 patients. Indications for EPS included nonsustained ventricular tachycardia, cardiomyopathy, syncope, near syncope, or palpitation. RESULTS Fifty-six of 68 patients had cardiomyopathy with left ventricular ejection fraction (LVEF) <or= 0.40. Mean LVEF was 0.29 +/- 0.13. ICA was detected at either the apex or base in 11 patients. ICA was concordant with MTWA in 87% (59 of 68) of the patients. ICA occurred at a greater magnitude than MTWA (3 +/- 2 mV vs. 2 +/- 2 microV, P <0.05). At a mean follow up of 4 years, 50% (34 of 68) of patients had an ICD implanted. Of patients with either a positive ICA or MTWA test, 49% (8 of 17) had an ICD implanted with appropriate shock in 75% (6 of 8) of the patients. Of patients with both normal ICA and MTWA tests, 51% (26 of 51) had an ICD for primary prevention, and appropriate ICD therapies occurred in 27% (7 of 26). After 1 year follow-up in patients with ICDs, the positive predictive values of ICA and MTWA in predicting ventricular arrhythmias were 14% and 17%, respectively. The negative predictive values for ICA and MTWA were both 82% at 4 years. CONCLUSION ICA is detectable from the right ventricle and can predict the patients at low risk for ventricular arrhythmias. Future applications of ICA may provide an integral part of arrhythmia detection and development of algorithms to divert shock therapy in ICDs.

Usefulness of left ventricular end-systolic dimension by echocardiography to predict reverse remodeling in patients with newly diagnosed severe left ventricular systolic dysfunction

In many patients with left ventricular (LV) systolic dysfunction, the LV ejection fraction (LVEF)-a surrogate for reverse remodeling-fails to improve despite optimal medical therapy. The early identification of such patients would allow instituting aggressive treatment, including early therapy with implantable cardioverter defibrillators. We sought to establish the predictors of reverse remodeling in patients with LV systolic dysfunction receiving optimal medical therapy. Patients (n = 568) with newly documented LVEF of ≤0.35, who had ≥1 follow-up echocardiogram after ≥3 months, were evaluated. Reverse remodeling was defined as improvement in LVEF to >0.35. The clinical, laboratory, and echocardiographic data were compared between patients with (n = 263) and without (n = 305) reverse remodeling. The mean follow-up was 27 ± 16 months. Patients who demonstrated reverse remodeling had a significantly greater mean follow-up LVEF (0.51 ± 0.09 vs 0.25 ± 0.08; p <0.001). On multivariate analysis, the baseline LV end-systolic diameter index was the strongest predictor of reverse remodeling (odds ratio 5.79; 95% confidence interval 1.82 to 18.46; p <0.001). Other independent predictors of reverse remodeling were female gender (odds ratio 1.88; 95% confidence interval 1.19 to 2.98; p = 0.007), and nonischemic cardiomyopathy (odds ratio 1.65; 95% confidence interval 1.05 to 2.58; p = 0.03). Baseline LVEF was not an independent predictor of reverse remodeling. In conclusion, among patients with newly diagnosed LV systolic dysfunction, the LV end-systolic diameter index, but not the LVEF, at diagnosis, was a strong predictor of reverse remodeling. Patients with a low likelihood of reverse remodeling might benefit from more aggressive heart failure therapy, including the possible early use of implantable cardioverter defibrillators.