Background—
Late potentials (LP) detected with signal-averaged ECGs are known to be useful in identifying patients at risk of Brugada syndrome (BS) and arrhythmogenic right ventricular cardiomyopathy (ARVC). Because the pathophysiology is clearly different between these disorders, we clarified the LP characteristics of these disorders.
Methods and Results—
This study included 15 BS and 12 ARVC patients and 20 healthy controls. All BS patients had characteristic ECG changes and symptomatic episodes. All ARVC patients had findings that were consistent with recent criteria. Three LP parameters (filtered QRS duration, root mean square voltage of the terminal 40 ms of the filtered QRS complex, and duration of low-amplitude signals [<40 µV] in the terminal, filtered QRS complex) were continuously measured for 24 hours using a novel Holter-based signal-averaged ECG system. The incidences of LP determination in BS (80%) and ARVC (91%) patients were higher than in healthy controls (5%;
P
<0.0001 in both) but did not differ between BS and ARVC patients. In BS patients, the dynamic changes of all LP parameters were observed, and they were pronounced at nighttime. On the contrary, these findings were not observed in ARVC patients. When the SD values of the 3 LP parameters (filtered QRS duration, root mean square voltage of the terminal 40 ms of the filtered QRS complex, and duration of low-amplitude signals [<40 µV] in the terminal, filtered QRS complex) over 24 hours were compared for the 2 patient groups, those values in BS patients were significantly greater than those in ARVC patients (
P
<0.0001 in all).
Conclusions—
LP characteristics detected by the Holter-based signal-averaged ECG system over 24 hours differ between BS and ARVC patients. Dynamic daily variations of LPs were seen only in BS patients. This may imply that mechanisms of lethal ventricular arrhythmia in BS may be more correlated with autonomic abnormality than that of ARVC.
AimsLoop diuretics are essential for the treatment of chronic heart failure (CHF) but short-acting diuretics are reported to induce sympathetic nervous system (SNS) activation. This study was performed to compare therapeutic effects of two loop diuretics, long-acting azosemide and short-acting furosemide, using 123 I-metaiodobenzylguanidine ( 123 I-MIBG) scintigraphy.
Methods and resultsTwenty-two patients with New York Heart Association class II-III heart failure and left ventricular dysfunction, who required treatment with a loop diuretic, were included. In this crossover study, 11 patients were randomized to azosemide treatment first and the remaining 11 patients to furosemide. Treatments were administered for 6 months and then patients were crossed over to the second treatment. 123 I-MIBG scintigraphy was performed before and 6 months after the start of treatment with each loop diuretic. Early and delayed images were obtained 20 min and 4 h after administration of 123 I-MIBG, respectively; and the heart/mediastinum (H/M) ratio and washout rate (WR) were measured. In addition, left ventricular ejection fraction (LVEF), levels of brain natriuretic peptide (BNP), and norepinephrine were measured before and 6 months after the start of treatment. No differences were observed between the two groups in terms of concomitant medication, cause of heart failure, H/M ratio, WR, BNP, norepinephrine, or LVEF. The azosemide group exhibited a significant increase in delayed image H/M ratio, and a significant decrease in WR and norepinephrine after the final administration compared with the furosemide group.
ConclusionThis study indicates that azosemide suppresses SNS activation compared with furosemide in patients with CHF, suggesting that long-acting loop diuretics may have more beneficial effects on the prognosis of CHF.--
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