The 3rd International Symposium on Left Atrial Appendage (ISLAA) was held on February 6-7, 2015 at the Marina del Rey Marriott in Los Angeles. The symposium was sponsored by the SCAI and HRS. The meeting reviewed anatomy, physiology, and pathophysiological aspects of the left atrial appendage (LAA), and discussed stroke prophylaxis strategies and devices for LAA occlusion. This multi-part blog will review the various topics covered during the meeting.
The first speaker was Dr. Samuel Asirvatham, who reviewed the anatomy and physiology of the left atrial appendage. Issues related to anatomy were reiterated by various other presenters as well.
Some of the important points included the following. The internal portion of the appendage contains some smooth portions and some pectinated. The more pectinated areas are the ostium and the tip; the area between is smooth, and is referred to as the body or the ‘landing zone’. Care must be taken during interventional procedures not to perforate this area.
The shape of the LAA has been characterized as being of at least 4 possible types. The most commonly described are the following:
• Cactus: with a dominant central lobe and secondary lobes arising from it superiorly and inferiorly.
• Chicken Wing: having a sharp bend in the dominant lobe of the LAA at some distance from the perceived ostium.
• Wind Sock: the primary structure is a dominant long lobe; there are variations in location and number of secondary or tertiary lobes; any type of device will close this.
• Cauliflower: most often associated with an embolic event; short overall length; variable number of lobes and lack of a dominant lobe; more irregular shape of orifice.
It was pointed out that the WATCHMAN device (Boston Scientific) requires an appendage of sufficient depth for successful placement.
The LAA also behaves like an endocrine organ, as atrial natriuretic factor is secreted from it in response to increased volume or pressure.
In addition, the LAA is a capacitance chamber, and if it is excised or occluded, LA/PV pressure is increased.
Dr. Luigi Di Biase discussed the role of the LAA in systemic thromboembolism and cited a 2012 Journal of the American College of Cardiology study, in which history of stroke/TIA was compared with LAA morphology as assessed by MRI or CT. Controlling for CHADS2 score, gender, and AF, those with the chicken wing morphology were 79% less likely to have a stroke or TIA. These findings could have an influence on anticoagulation approaches.
Dr. Andrea Natale presented data about the role of the LAA in atrial arrhythmia origination and maintenance. The LAA has been cited as a source for atrial fibrillation initiation. In one study, the LAA was responsible for arrhythmias in 27% of patients presenting for repeat procedures. Isolating the LAA has improved ablation outcomes in a few studies. In order to study this further, the BELIEF study was proposed. It will be a prospective randomized study to assess whether empirical LAA isolation along with standard PVI and ablation of extrapulmonary triggers is superior to standard approach alone for persistent or longstanding persistent AF patients. There are implications here for considering ablating the LAA prior to inserting a LAA occlusive device.
Dr. Amin Al-Ahmad reviewed various risk assessment tools for determining stroke prophylaxis and bleeding.
CHADS2 score has had the advantages of being easy to use and being patient specific. The disadvantages are that it was derived from a sicker and older population, with a small number in the low risk category; possible selection bias also occurred (those not treated with warfarin were not included).
The CHA2DS2VASc has been shown to be superior in identifying patients in the low risk group, and was recommended in the 2014 AHA/ACC/HRS guidelines for atrial fibrillation management.
C= CHF 1 point 1 point
H= Hypertension 1 point 1 point
A= Age >75 years 1 point 2 points
D= Diabetes 1 point 1 point
S= Prior Stroke/TIA 2 points 2 points
V= Vascular Disease* 1 point
A= Age 65-74 1 point
S= Sex Category (ie female sex) 1 point
TOTAL: 6 points 9 points
*Defined as previous MI, peripheral arterial disease, or aortic plaque
Framingham Risk Score: includes information on age, gender, systolic BP, DM, and prior stroke or TIA. The scoring system is good for identifying low-risk individuals.
Atria Risk Score: This is derived from the Kaiser Permanente Health Plan Database of Northern California and includes all pts ≥18 with AF. Data points include age, sex, DM, CHF, HTN, proteinuria, and eGFR <45 or ESRD.
HEMORR2HAGES: This was developed from the National Registry of Atrial Fibrillation (NRAF). The scoring system gives 2 points for prior bleed, and 1 point each for hepatic or renal disease, ethanol abuse, malignancy, older than 75 years, reduced platelet count or function, genetic factors, excessive fall risk, and stroke.
HAS-BLED: This was derived from the European Heart Survey of AF. Factors included are: HTN 1; abnormal renal or liver function 1 or 2; stroke 1; bleeding 1; labile INR; elderly (>65); drugs or ETOH 1 or 2.
HAS-BLED is considered easiest to use among ATRIA and HEMORRHAGES and may help determine high-risk individuals. However, HAS-BLED has not been recommended for use in guidelines because its clinical utility has been insufficient.
Linda C. Moulton, RN, MS is the Owner of the Critical Care ED and C.C.E. Consulting, and Faculty of the Order and Disorder Electrophysiology Training Program in New Berlin, Illinois.