Predictors of left atrium appendage clot detection despite on-target warfarin prevention for atrial fibrillation.

BACKGROUND AND PURPOSE: The antithrombotic management of atrial fibrillation (AF) is currently based on clinical scores (CHADS(2) or CHA(2)DS(2)VASc). The prevalence of left atrium (LA) thrombi in effectively anticoagulated AF patients has been reported as being up to 7.7 %. We tried to correlate LA/LA appendage (LAA) thrombus detection with possible clinical predictors in warfarin-treated patients. METHODS: We performed trans-esophageal echocardiography on 430 patients (mean age, 60.3 ± 9.8 years) receiving oral anticoagulant (OAC) therapy and undergoing pulmonary vein isolation. In 10/430 (2.3 %), an LA thrombus was found despite therapeutic OAC (mean INR 2.6 ± 0.6; range, 2.0-3.8) over the previous 4 weeks. RESULTS: Two study groups were identified: 1. T-positive group = with LAA thrombus (10 patients) 2. T-negative group = without LAA thrombus (420 patients) The T-positive patients had a higher CHADS(2) score (1.5 ± 0.7 versus 0.7 ± 0.8; p = 0.004), a lower LVEF (54.7 ± 9.5 % versus 60.2 ± 7.4; p = 0.02), and a larger LA size (LA diameter, 56 ± 12.2 mm versus 46 ± 6.5 mm; p < 0.001and normalized LA volume: 140.2 ± 66 ml/m² vs. 67 ± 39 ml/m²; p < 0.05). On multivariate analysis, a larger LA diameter and normalized LA volume (OR, 1.14; 95 % C.I., 1.04-1.26; p = 0.006 and OR, 1.02; 95 % C.I., 1.01-1.03; p = 0.001, respectively) and a higher CHA(2)DS(2)VASc score (OR, 2.4; 95 % C.I., 1.4-4.2; p = 0.001) predicted left atrium appendage (LAA) thrombus. In another 42/430 (9.8 %) patients, an LA spontaneous echo-contrast (SEC) was detected. Thus, cumulatively, 52/430 (12.1 %) patients had either LAA thrombi (10 patients) or SEC (42 patients). LA diameter continued to predict the presence of either thrombi or SEC (OR, 1.14; 95 % C.I., 1.07-1.2; p < 0.05). CONCLUSIONS: We found a 2.3 % prevalence of LA thrombus (12.1 % when SEC was also considered). The thrombus was present despite on-target warfarin prevention. In addition to a higher CHA(2)DS(2)VASc score, a larger LA size was a strong predictor of clot detection.

Activation mapping to determine the mechanism of atrial tachycardia when pacing techniques are not feasible.

AIM: Atrial tachycardia/flutter (ATAF) could be sustained by a focus or a reentry circuit, which mapping differs significantly. Entrainment mapping is widely used to detect reentry, but it is not always feasible. We evaluated an activation mapping protocol to differentiate macro, micro-reentrant and focal ATAFs. METHODS: Among 454 patients who underwent ablation for supraventricular tachycardia (SVT) between December, 2004 and August, 2008, 52 ATAF patients were selected and assessed by means of activation mapping (study mapping protocol). The remaining 402 cases (AVNRT, AVRT, and common atrial flutter) were excluded. RESULTS: Fifty-eight ATAF morphologies were mapped (mean CL 297.2±98 ms). The protocol identified the ATAF mechanism in 53/58 (91%, 52 successfully ablated) morphologies, while the mapping technique failed in 5/58 (9%) cases/patients. Among the 53 ATAF diagnoses, 25/53 (47%) were macroreentrant ATAFs (MATs), whereas 12/53 (23%) were focal ATAFs (FATs) or microreentrant ATAFs (MIATs) (16/53, 30%). Ablation was successful in 25/25 cases of the MAT group, in 11/12 (91.7%) cases of the FAT group, and in 16/16 cases of the MIAT group. At the end of the procedure, no ATAF was inducible in 44/52 (85%) patients. The study protocol was successfully validated in 20 patients (10 with AVNRT, and 10 with common atrial flutter) of the control group. After a mean follow-up of 21.5±12.5 months, 36/52 (70%) pts resulted free from ATAF. Non-inducibility predicted long-term freedom from ATAF (92.1 % vs. 60 %, P=0.005, OR 0.09; 95% CI 0.18-0.51, P=0.006). CONCLUSION: Activation mapping alone may be reliable to determine the ATAF mechanism, especially when pacing techniques are not feasible.