The natural history of lone atrial flutter

degree than RV pacing, regardless of the presence of LV dysfunction or a left bundle branch block. Perspective: Prior studies have demonstrated that AVJA/RV pacing significantly improves functional capacity in patients with uncontrolled AF. The results of this study suggest that functional capacity might improve to an even greater degree with LV pacing. However, echocardiographic parameters were evaluated only acutely, at rest, and in the supine position. Whether these results have any relevance to short- or longterm functional capacity is unknown, and it is premature to routinely employ LV pacing after AVJA. FM

catheter ablation (CA) when mapping is guided by a noncontact mapping system? Methods: A noncontact mapping system was used to guide CA in 13 consecutive patients (mean age 45 years) with FAT (mean rate 150/min). Dynamic isopotential maps based on 3000 virtual endocardial electrograms were used to identify the site of origin (SOO) and breakout site of 14 FATs. Radiofrequency ablation was performed with a conventional ablation catheter. Results: The SOO was in the crista terminalis (CT, n⫽8), right atrial free wall (n⫽3) or other right atrial site (n⫽3). There were preferential conduction pathways from the SOO to the breakout site, either along the CT or in other regions of the right atrium, and the breakout sites were located up to several centimeters from the SOO. The FATs were eliminated by a mean of 11 applications of radiofrequency energy at either the SOO or proximal portion of the preferential pathway. Eleven of 13 patients (85%) remained free of FAT during a mean of 8 months of follow-up. Conclusions: FATs originate at a point source, most commonly along the CT, and there is preferential conduction from the SOO to a breakout site that may be located several centimeters from the SOO. FAT may be ablated either at the SOO or at the proximal portion of the preferential pathway. Perspective: The finding that FATs can be successfully ablated at sites other than the SOO has important therapeutic implications for catheter ablation. However, the large number of radiofrequency applications required for CA raises questions about the accuracy with which noncontact mapping identified successful target sites for ablation. FM

The Natural History of Lone Atrial Flutter Halligan SC, Gersh BJ, Brown RD, et al. Ann Intern Med 2004; 140:265– 8. Study Question: What is the risk of stroke in lone atrial flutter (AFI)? Methods: This was a retrospective analysis of 59 patients (mean age 70 years) with lone AFI. Patients with controlled hypertension were included, but patients with structural heart disease were excluded. The prevalences of stroke and atrial fibrillation (AF) were determined during a mean follow-up of 10 years. There were two control groups: 1) a sample of the general population in which stroke rates were determined; 2) 145 patients with lone AF. Results: During a mean follow-up of 5 years, 56% of patients with lone AFI were documented to also have AF. The incidence of stroke or transient ischemic attack in patients with lone AFI was 23% at 5 years and 35% at 10 years. The mean age at the time of stroke was 80 years. In comparison, the cerebrovascular ischemic event rates in an age- and sex-matched sample of the general population were 6% at 5 years and 11% at 10 years. Compared to patients with AF, the risk of a cerebrovascular ischemic event was 2.6-fold higher among patients with AFI. Conclusions: Patients with lone AFI often develop AF and have a risk of ischemic cardiovascular episodes that is at least as high as among patients with lone AF. Patients ⬎65-years-old with AFI should be anticoagulated. Perspective: Several recent studies have demonstrated that the risk of stroke in patients with AFI is higher than previously thought. However, because AF occurs commonly in patients with AFI, it is unclear whether this stroke risk is attributable to the AFI itself, or to AF. In any case, the present study provides additional support for the recommendation that patients with AFI be anticoagulated using the same guidelines as in AF. FM

A Comparison of Vasopressin and Epinephrine for Out-of-Hospital Cardiopulmonary Resuscitation Wenzel V, Krismer AC, Arntz HR, Sitter H, Stadlbauer KH, Lindner KH. N Engl J Med 2004;350:105–13. Study Question: Does vasopressin administered during cardiopulmonary resuscitation (CPR) improve survival to hospital admission (SHA) compared to epinephrine? Methods: This was a randomized, double-blind comparison of vasopressin and epinephrine in 1186 patients (mean age 66 years) with out-of-hospital cardiac arrest. Patients presenting with ventricular fibrillation (VF) underwent randomization after three defibrillation failures, and patients with pulseless electrical activity (PEA) or asystole underwent randomization immediately. The patients received 1–2 intravenous injections of either 40 IU of vasopressin (n⫽589) or 1 mg of epinephrine (n⫽597). If needed, an additional dose of epinephrine was administered at the discretion of the emergency physician. The 1° end point was SHA. Results: SHA was approximately 45% in both treatment groups among patients with VF and approximately 32% in both groups among patients with PEA. Among patients with asystole, SHA was higher in the vasopressin group (29%) than in the epinephrine group (20%), as was survival

Focal Atrial Tachycardia. New Insight From Noncontact Mapping and Catheter Ablation Higa S, Tai CT, Lin YJ, et al. Circulation 2004;109:84 –91. Study Question: What are the activation patterns of focal atrial tachycardia (FAT) and the results of radiofrequency

ACC CURRENT JOURNAL REVIEW Apr 2004

51