Multiple recurrences of VF occurred in 27% of patients with early repolarization abnormality and may be life threatening. Isoproterenol in acute cases and quinidine in chronic cases are effective AADs.

In a European healthcare setting, prophylactic ICD implantation may be cost-effective if current guidelines for patients with a reduced LVEF are followed.

Cardiac resynchronization therapy (CRT) decreases muscle sympathetic nerve activity (MSNA) in patients with severe congestive heart failure (CHF) and cardiac asynchrony. Whether this affects equally patients who clinically respond or not to CRT is unknown. We tested the hypothesis that the favorable effects of CRT on MSNA disappear on CRT interruption only in those who respond to CRT. Twenty-three consecutive CHF patients participated in the study, among whom 16 presented a symptomatic improvement by one or more New York Heart Association (NYHA) functional classes 15 +/- 5 mo after CRT (responders), and seven had not improved after 12 +/- 4 mo of CRT (nonresponders). MSNA and echocardiographic recordings were obtained in random order during atrio-right ventricular pacing (ARV), without stimulation in patients who were not pacemaker dependent (OFF, n = 17), and during atrio-biventricular pacing (BIV). Responders had a longer 6-min walking distance, a lower NYHA class and brain natriuretic peptide levels, and a better quality of life than did nonresponders (all P < 0.05). MSNA increased by 25 +/- 7% in the responders, whereas it remained unchanged in the nonresponders, when shifting from the BIV mode to a nonsynchronous condition (ARV and OFF modes) (P < 0.01). Cardiac output decreased by 0.7 +/- 0.2 l/min in the responders but did not change when shifting from the BIV mode to the nonsynchronous pacing mode in the nonresponders (P < 0.01). In conclusion, reversible sympathoinhibition is a marker of the clinical response to CRT.

MD; for the ATP Multicenter StudyBackground-The origin of 40% of syncope cases remains unknown even after a complete diagnostic workup. Previous studies have suggested that ATP testing has value in selecting successful therapy. This patient-blinded, multicenter, randomized superiority trial tested whether, in patients with syncope of unknown origin, selecting cardiac pacing in those with a positive ATP test leads to fewer recurrences than those who do not receive pacing. Methods and Results-From 2000 to 2005, 80 consenting patients (mean age, 75.9Ϯ7.7 years; 81% women; 56% without diagnosed structural heart disease) with syncope of unknown origin and atrioventricular or sinoatrial block lasting Ͼ10 seconds (average, 17.9Ϯ6.8 seconds) under ATP administration (20-mg IV bolus) were recruited from 10 hospitals, implanted with programmable pacemakers, and randomized to either active pacing (dual-chamber pacing at 70 bpm) or backup pacing (atrial pacing at 30 bpm). Patients were followed up regularly for up to 5 years for any syncope recurrence, the primary outcome. Mean follow-up was 16 months. Syncope recurred in 8 of 39 patients (21%) randomized to active pacing and in 27 of 41 (66%) randomized to backup pacing (control), yielding a hazard ratio of 0.25 (95% confidence interval, 0.12-0.56). After recurrence, the 27 recurrent control patients were reprogrammed to active pacing, and only 1 reported subsequent syncope. Conclusion-This study suggests that, in elderly patients with syncope of unknown origin and positive ATP tests, active dual-chamber pacing reduces syncope recurrence risk by 75% (95% confidence interval, 44 -88). Clinical Trial Registration-URL: http://www.controlled-trials.com/ISRCTN00029383. Unique identifier: ISRCTN00029383. Key Words: adenosine triphosphate Ⅲ pacemaker, artificial Ⅲ randomized controlled trials Ⅲ syncope Ⅲ syncope, vasovagal S yncope is defined as a transient, short-lasting, and self-limiting loss of consciousness caused by temporary cerebral hypoperfusion. 1 The incidence of syncope increases significantly with age. 1,2 Syncope of unknown origin (SUO) is defined as a syncope for which no clear explanation has been found after a conventional workup; it heavily affects the cost of medical care. 3,4 As the longevity of the Western population increases, 5 the incidence of syncope and of secondary injuries will also increase with time. Despite an extensive workup, the origin of syncope remains unexplained in 20% to 40% of patients. 1,6,7 SUO may be neurally mediated; its current treatment is based on the avoidance of triggering situations, orthostatic training, and drug therapy, all with uncertain long-term results. Clinical Perspective on p 36The ATP test was introduced in 1986 to identify those SUO patients with predominantly neurally mediated cardiac inhibition who may benefit from cardiac pacing therapy. 8 The present clinical trial was carried out to test the hypothesis that, in patients with SUO, cardiac pacing instituted on the basis of a positive ATP test is an effective long...