Presence and Duration of Atrial Fibrillation Detected by Continuous Monitoring: Crucial Implications for the Risk of Thromboembolic Events

AF and the Risk of Thromboembolic Events. Introduction: Asymptomatic atrial fibrillation (AF) can expose patients to the risk of stroke. The primary objective of this study was to assess the incidence of thromboembolic events in relationship with CHADS₂ (congestive heart failure, hypertension, age ≥75 years, diabetes mellitus, and prior stroke, or transient ischemic attack) score and AF presence/duration. The secondary objective was to compare intermittent versus continuous monitoring strategies. Methods and Results: Data from patients with an implanted pacemaker and a history of AF were analyzed. Thromboembolic risk was quantified through CHADS₂ score. Three AF groups were considered: patients with <5‐minutes AF on 1 day (AF‐free); patients with >5‐minutes AF on 1 day but <24 hours (AF‐5 minutes); patients with AF episodes >24 hours (AF‐24 hours). Monitoring strategies involving 24‐hour Holter, 1‐week Holter, and 30‐day Holter were simulated. Data from 568 patients continuously monitored for 1 year were analyzed: 171 (30%) had CHADS₂ score = 0; 269 (47%) had CHADS₂ score = 1; 111 (20%) had CHADS₂ score = 2; and 17 (3%) had CHADS₂ score ≥ 3. During follow‐up, 14 patients (2.5%) had an ischemic thromboembolic event. AF‐24 hours patients numbered 223 (39.2%); AF‐5 minutes, 179 (31.5%); and AF‐free, 29.2%. By combining AF presence/duration with CHADS₂ score, two subpopulations with markedly different risks of events (0.8% vs 5%, P = 0.035) were identified, the former corresponding to AF‐free with CHADS₂≤2, or AF‐5 minutes with CHADS₂≤1, or AF‐24 hours with CHADS₂= 0. The mean sensitivity in detecting an AF episode lasting >5 minutes was 44.4%, 50.4%, and 65.1% for 24‐hour Holter, 1‐week Holter, and 1‐month Holter monitoring, respectively. Conclusion: In patients with recurrent AF episodes, risk stratification for thromboembolic events can be improved by combining CHADS₂ score with AF presence/duration. (J Cardiovasc Electrophysiol, Vol. 20, pp. 241‐248, March 2009)     

Left Atrial Dysfunction in Patients with Patent Foramen Ovale and Atrial Septal Aneurysm Scheduled for Transcathter Closure May Play a Role in Aura Genesis

Background: It has been suggested that a left atrial (LA) dysfunction induced by large shunt and large atrial septal aneurysm (ASA) may act as a concurrent mechanism of arterial embolism in patients with patent foramen ovale (PFO) and prior stroke. We aimed to evaluate the potential contribution of this mechanism as trigger of migraine in patients with PFO. Methods: From January 2007 to September 2009, we prospectively enrolled subjects with migraine who underwent percutaneous PFO closure. Echocardiographic parameter of LA dysfunction was evaluated: pre‐ and postoperative values were compared to values of different sex and heart rate matched populations: 30 healthy patients, 21 migraine patients without PFO (MwoPFO), and a group of 25 PFO patients without migraine (PFOwoM). The Migraine Disability Assessment Score (MIDAS) was used to assess the incidence and severity of migraine. Results: Forty‐five patients (38 females, mean age 38 ± 6.7 years, mean MIDAS 35.8 ± 4.7, and 28 patients with migraine with aura) fulfilled the inclusion criteria. After successful percutaneous closure (mean follow‐up of 18.2 ± 4.8 months), PFO closure remained complete in 95%; 35 of 45 patients reported resolution or amelioration of migraine (mean MIDAS score 12.3 ± 8.8, P < 0.03). All patients with aura reported aura resolution. Preclosure values demonstrated significantly greater LA dysfunction, when compared with healthy and MwoPFO groups. Among patients in the study group, only patients with migraine with aura showed LA dysfunction comparable to PFOwoM patients. Conclusion: This study suggests that LA dysfunction probably does not contribute to migraine itself but may play a role in the genesis of aura symptoms. (J Interven Cardiol 2010;23:370–376)     

Inhibition of Feline Immunodeficiency Virus Infectionin Vitroby Envelope Glycoprotein Synthetic Peptides

Sixty-six 20- to 23-amino-acid synthetic peptides, partially overlapping by 10–12 amino acids, spanning the entire sequence of the envelope SU and TM glycoproteins of the Petaluma isolate of FIV, have been used to investigate the Env domains involved in viral infection. Peptides 5 to 7, spanning amino acids²²⁵E–P²⁶⁴located in a conserved region of the SU protein, and peptides 58 to 61, spanning amino acids⁷⁵⁷N–P⁸⁰⁶and encompassing hypervariable region 8 of TM protein, exhibited a remarkable and specific antiviral effect against the homologous and one heterologous isolate, as judged by inhibition of FIV-induced syncytium formation and p25 production in CrFK cells. Peptides 5 and 7, but not peptides 58 and 59, also inhibited viral replication of a fresh FIV isolate on nontransformed lymphoid cells. By flow cytometry, peptides 5, 7, 58, and 59 were shown to bind the surface of FIV permissive cells. The antiviral activity of peptides 5 and 7, however, was time-dependent, as inhibition of FIV replication was seen when the peptides were administered before or within 3 hr after virus inoculation; in contrast, TM peptides 58 and 59 exerted a potent inhibitory effect when added up to 24 hr after virus inoculation. Circular dychroism analysis showed that peptide 5 folds to a helical conformation in the presence of a hydrophobic environment. Although the basis for the antiviral action of the peptides is not understood, our data suggest that the inhibitory peptides may act by interacting with cell-surface molecules involved in viral infection.     

Activated Pyrolytic Carbon Tip Pacing Leads: An Alternative to Steroid-Eluting Pacing Leads?

Pyrolytic carbon technology is known for its excellent mechanical properties and electrical conductivity; it is particularly biocompatible and does not require high production costs. The Sorin S100/4 lead is a ventricular passive fixation lead with a hemispherical electrode surface area of 4 mm²; the stimulating tip is made of a graphite core coated by a thin activated pyrolytic carbon layer. We evaluated the acute and medium-term performance of the unipolar version of this lead in 65 patients. At implantation, pacing threshold (at 0.5 ms) was 0.26 ± 0.08 V; pacing impedance (at 5 V and 0.5 ms) was 537 ± 94 Ω and Ft wave amplitude was 15.0 ± 5.5 mV. No lead related complications (dislodgment, perforation, exit block, etc.) occurred in any patient; one patient presented with a wire fracture after 26 months, due to subclavian crush syndrome. Follow-up procedures were performed at 1 week, and 2-, 10-, 18-, and 30-months postimplant. Since the leads were connected to pacemakers from different manufacturers, either voltage or duration thresholds were measured, In approximately two thirds of the patients, with an output of 2.5 V, a mean duration threshold of 0.16 ± 0.13 ms at 1 week, 0.12 ± 0.08 ms at 2 months, 0.11 ± 0.06 ms at 10 months, 0.09 ± 0.06 ms at 18 months, and 0.07 ± 0.03 ms at 30 months, was measured. In the remaining one-third of the patients, a comparable voltage threshold trend was measured. The mean pacing impedance showed a transient drop at 1 week, and then increased to a plateau of about 600 fl reached after 10 months. No sensing defect occurred in any patient. Our data show good acute and intermediate-term results of the S100/4 lead; the early rise in threshold was remarkably blunted. Activated pyrolytic carbon tip leads might therefore be considered as a possible, inexpensive alternative to steroideluting leads.