In patients with advanced heart failure and LBBB, baseline SPWMD is a strong predictor of the occurrence of reverse remodeling after CRT, thus suggesting its usefulness in identifying patients likely to benefit from biventricular pacing.

Background-Depressed baroreflex sensitivity obtained by means of a phenylephrine test plays a prognostic role in patients with a previous myocardial infarction. Our purpose was to evaluate the correlation and agreement between the baroreflex sensitivity obtained with phenylephrine and that obtained by two noninvasive methods: the ␣-index and sequence analysis. Methods and Results-The ␣-index was measured by means of the spectral analysis of RR and systolic blood pressure variabilities in both the high-and low-frequency bands; sequences were identified from simultaneously recorded time series in which the RR and systolic blood pressure concurrently increased or decreased. Noninvasive baroreflex sensitivity tests were performed during both spontaneous and controlled respiration. Fifty-two consecutive patients with recent myocardial infarction underwent the analyses. Although the correlations between phenylephrine and either of the noninvasive methods were always significant, those found during controlled respiration had the highest r values (rϭ.70). However, the limits of agreement calculated by means of the Bland and Altman method were wide for both noninvasive methods. Conclusions-The

Objective: The aims of this study were to determine the relationships between oscillations in systolic blood pressure and heart period at different breathing frequencies and to investigate the role of sympathetic contribution to this relationship. Methods: Fourteen healthy Ž . volunteers underwent three randomized periods of controlled breathing at 6, 10 and 16 breathsrmin. ECG RR , respiratory signal Ž . Ž . RESP and systolic blood pressure SBP were continuously recorded. and RESP, and RR and SBP RR-SBP were also assessed. When the K of RR-SBP in the respiratory band was ) 0.5, we considered the phase and calculated the closed-loop gain between the two signals. Seven subjects were also studied after chronic metoprolol treatment. Results: Although the mean values of RR and SBP did not differ between the three periods of breathing, the higher the Ž . respiratory rate, the smaller the RR and SBP . The phase was always negative SBP changes preceded RR changes , thus Resp Resp Resp Resp suggesting a baroreflex link. The higher the respiratory rate, the lower the gain and phase. Pharmacological b-adrenoceptor blockade increased the gain and shifted the phase, but the relationships found at baseline between the respiratory rate and both the gain and phase remained unchanged. Conclusions: The effect of breath rate on the relationship between heart rate and systolic pressure variabilities is a frequency-dependent phenomenon that is also independent of the sympathetic drive. q

In patients with DCM, QT dynamicity is independently associated with the occurrence of major arrhythmic events and improves the predictive accuracy of stratifying arrhythmic risk of these patients.