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- Gold, Michael R, et al.
(författare)
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Impact of atrial prevention pacing on atrial fibrillation burden: primary results of the Study of Atrial Fibrillation Reduction (SAFARI) trial.
- 2009
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Ingår i: Heart rhythm : the official journal of the Heart Rhythm Society. - : Elsevier BV. - 1556-3871. ; 6:3, s. 295-301
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Tidskriftsartikel (refereegranskat)abstract
- BACKGROUND: The role of atrial-based pacing algorithms in preventing atrial fibrillation (AF) remains controversial. The inconsistent results noted in previous trials may be due in part to differences in endpoints, pacing algorithms, and study design. SAFARI, a worldwide, prospective, randomized clinical trial, was designed to address these issues and to evaluate the safety and efficacy of a suite of prevention pacing therapies (PPTs) among patients with paroxysmal AF. METHODS AND RESULTS: Patients who met standard pacemaker indications and documented symptomatic AF were implanted with a pacemaker (Vitatron Selection 9000). At 4 months, only patients with documented AF despite dual-chamber pacing were randomized to PPTs ON or PPTs OFF and followed for 6 months. Incidence of permanent AF and change in AF burden were compared between the two groups. Among the 555 patients enrolled, 240 had AF burden at 4 months and were randomized. The risk of developing permanent AF was similar in both groups (0 in the PPTs ON group vs. 3 in the OFF group). However, there was a significant reduction in AF burden between baseline and 10-month follow-up in the ON group compared with the OFF group (median decrease of 0.08 hours/day vs no change, P = .03). CONCLUSION: Among patients with paroxysmal AF and standard bradycardia indications, PPTs are safe and associated with less AF burden compared with conventional pacing.
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| 2. |
- Sahlén, Anders, et al.
(författare)
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Cardiac fatigue in long-distance runners is associated with ventricular repolarization abnormalities.
- 2009
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Ingår i: Heart rhythm : the official journal of the Heart Rhythm Society. - : Elsevier BV. - 1556-3871 .- 1547-5271. ; 6:4, s. 512-9
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Tidskriftsartikel (refereegranskat)abstract
- BACKGROUND: Prolonged exercise can induce cardiac fatigue, which is characterized by biomarker release and impaired myocardial function. The impact on ventricular electrophysiology is largely unknown. OBJECTIVE: The objective of this study was to examine changes in ventricular repolarization after a 30-km cross-country race in runners aged >or=55 years. METHODS: Fifteen healthy participants (62 +/- 5 years) were assessed using biomarkers (N-terminal pro-brain natriuretic peptide [NT-proBNP], troponin T [TnT]), tissue Doppler echocardiography, and vectorcardiography at baseline, within 1 hour postrace and on days 1 and 6 postrace. RESULTS: During the race, NT-proBNP increased from 42 ng/L (interquartile range 25-117) to 187 ng/L (113-464), and TnT increased from undetectable levels to 0.03 microg/L (0.015-0.05). Global strain (19.1% +/- 2.2%) decreased on day 1 (17.2% +/- 1.8%) and day 6 (17.9% +/- 1.5%; P <.01). QT(c) increased from 431 +/- 15 ms prerace to 445 +/- 22 ms postrace and 445 +/- 15 ms on day 1 (P <.05), mainly because of an increased T(peak-end) interval (prerace 108 +/- 13 ms, postrace 127 +/- 43 ms, day 1 127 +/- 43 ms; P <.05). Postrace, T(area) (baseline 75 +/- 26 microVs) peaked on day 1 (105 +/- 42 microVs) and remained high on day 6 (89 +/- 37 microVs; P <.05). Runners with higher baseline NT-proBNP developed greater impairment of myocardial velocities (rho = -0.68 to -0.54; P <.05) and a larger increase in T(area) (rho = 0.73; P <.01). CONCLUSION: Cardiac fatigue induced by prolonged exertion is associated with sustained abnormalities in ventricular repolarization. Runners with higher baseline NT-proBNP are especially liable to such alterations of cardiac function.
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| 3. |
- Schwieler, J H, et al.
(författare)
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Reentry in an accessory atrioventricular pathway as a trigger for atrial fibrillation initiation in manifest Wolff-Parkinson-White syndrome: A matter of reflection?
- 2008
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Ingår i: Heart rhythm : the official journal of the Heart Rhythm Society. - : Elsevier BV. - 1556-3871 .- 1547-5271. ; 5:9, s. 1238-47
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Tidskriftsartikel (refereegranskat)abstract
- BACKGROUND: Patients with an accessory pathway (AP) have an increased propensity to develop atrial fibrillation (AF), but the mechanism is unknown. OBJECTIVE: The purpose of this study was to identify crucial risk factors and to test the hypothesis that reflection and/or microreentry of atrial impulses propagating into the AP triggers AF. METHODS: Five hundred thirty-four patients successfully treated with radiofrequency ablation of AP at two university hospitals were evaluated. Patients were separated into those with concealed vs those with manifest AP in terms of their propensity to develop AF. To investigate AF triggering mechanisms, linear and branched two-dimensional models of atrium-to-ventricle propagation across a heterogeneous 1 x 6 AP using human ionic kinetics were simulated. RESULTS: A history of AF was twice as common in patients with manifest AP vs concealed AP irrespective of AP location. AF was more likely to occur in older males and in patients with larger atria. There was no correlation between AF history and AP refractory measures. However, the electrophysiologic properties of APs seemed to fulfill the prerequisites for reflection and/or microreentry of atrially initiated impulses. In the linear AP model, repetitive atrial stimulation resulted in progressively larger delay of atrium-to-ventricle propagation across the passive segment. Eventually, sufficient time for repolarization of the atrial segment allowed for reflection of an impulse that activated the entire atrium and by wavefront-wavetail interaction with a new atrial stimulus AF reentry was initiated. Simulations using the branched model showed that microreentry at the ventricular insertion of the AP could also initiate AF via retrograde atrial activation as a result of unidirectional block at the AP-ventricle junction. CONCLUSION: Propensity for AF in patients with an AP is strongly related to preexcitation, larger atria, male gender, and older age. Reflection and microreentry at the AP may be important for AF initiation in patients with manifest (preexcited) Wolff-Parkinson-White syndrome. Similar mechanisms also may trigger AF in patients without an AP.
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