Jae Sun Uhm

Impact of increased orifice size and decreased flow velocity of left atrial appendage on stroke in nonvalvular atrial fibrillation.

The structural and functional characteristics of left atrial appendage (LAA) in patients with atrial fibrillation (AF) with previous stroke remain incompletely elucidated. This study investigated whether a larger LAA orifice is related to decreased LAA flow velocity and stroke in nonvalvular AF. The dimension, morphology, and flow velocity of LAA were compared in patients with nonvalvular AF with (stroke group, n = 67, mean age 66 ± 9 years) and without ischemic stroke (no-stroke group, n = 151, mean age 56 ± 10 years). Compared with no-stroke group, the stroke group had larger LA dimension (4.7 ± 0.8 vs 4.2 ± 0.6 cm, p <0.001), larger LAA orifice area (4.5 ± 1.5 vs 3.0 ± 1.1 cm(2), p <0.001), and slower LAA flow velocity (36 ± 19 vs 55 ± 20 cm/s, p <0.001). LAA flow velocity was negatively correlated with LAA orifice size (R = -0.48, p <0.001). After adjustment for multiple potential confounding factors including CHA2DS2-VASc score, persistent AF, and LA dimension, large LAA orifice area (odds ratio 6.16, 95% confidence interval 2.67 to 14.18, p <0.001) and slow LAA velocity (odds ratio 3.59, 95% confidence interval 1.42 to 9.08, p = 0.007) were found to be significant risk factors of stroke. In patients with LAA flow velocity <37.0 cm/s, patients with large LAA orifice (>3.5 cm(2)) had greater incidence of stroke than those with LAA orifice of ≤3.5 cm(2) (75% vs 23%, p <0.001). In conclusion, LAA orifice enlargement was related to stroke risk in patients with nonvalvular AF even after adjustment for other risk factors, and it could be the cause of decreased flow velocity in LAA.

Long duration of radiofrequency energy delivery is an independent predictor of clinical recurrence after catheter ablation of atrial fibrillation: Over 500 cases experience

BACKGROUNDnAlthough radiofrequency catheter ablation (RFCA) for atrial fibrillation (AF) is an effective rhythm control strategy, there is a substantial amount of recurrence. We explored the predictors of AF recurrence after RFCA with consistent ablation strategy.nnnMETHODS AND RESULTSnThis study included 575 patients (77% male, 56 ± 11 years old) with AF (65.7% paroxysmal AF [PAF], 34.3% persistent AF [PeAF]) who underwent RFCA. We evaluated the clinical, serological, and electrophysiological parameters thereof.nnnRESULTSn1. During 15 ± 7 months of follow-up, patients who experienced AF recurrence (21.8%) were older (58 ± 10 vs. 55 ± 11 years old, p=0.019) and more likely to have PeAF (50.4% vs. 29.4%, p<0.001) and greater LA volume (137.3 ± 49.1 vs. 116.6 ± 37.9 mL, p<0.001). 2. In patients with clinical recurrence after RFCA, both ablation time (110.1 ± 43.8 vs. 92.3 ± 30.1 min, p<0.001) and procedure time (222.7 ± 79.6 vs. 205.8 ± 58.8 min, p<0.001) were prolonged, and the early recurrence rate within 3 months of the procedure was higher (63.0% vs. 26.4%, p<0.001) than those without clinical recurrence. 3. In logistic regression analysis, LA volume (OR 1.008, CI 1.001-1.014), ablation time (per quartile, OR 1.380, CI 1.031-1.847), and early recurrence (OR 3.858, CI 2.420-6.150) were independent risk factors for recurrence of AF after RFCA.nnnCONCLUSIONnIn this single center consistent study of over 500 cases of AF ablation, patients with AF recurrence had a larger atrium, longer ablation time, and a higher chance of early recurrence than those remained in sinus rhythm. Inadvertent, long duration of ablation was an independent predictor of worse clinical outcomes after catheter ablation of AF.

New-onset atrial fibrillation predicts long-term newly developed atrial fibrillation after coronary artery bypass graft

BACKGROUNDnNew-onset postoperative atrial fibrillation (POAF) is associated with poor short- and long-term outcomes after isolated coronary artery bypass graft (CABG). This study evaluated whether new-onset POAF is independently associated with long-term (>1 year) atrial fibrillation (AF) and mortality.nnnMETHODSnAmong 1,171 consecutive patients who had undergone CABG, AF and mortality were compared between patients with POAF (POAF group, n = 244) and those without POAF (no-POAF group, n = 927) after propensity score matching.nnnRESULTSnDuring the follow-up period of 41 ± 23 months (range 0-87 months), the POAF group had a higher incidence of total (20/927 [2.2%] vs 46/244 [18.9%], P < .001) and long-term AF recurrence (13/927 [1.4%] vs 25/244 [10.2%], P < .001). Even after propensity score matching, the POAF group still showed a higher incidence of total (7/244 [2.9%] vs 46/224 [18.9%], P < .001) and long-term AF recurrence (4/244 [1.6%] vs 25/224 [10.2%], P < .001). In addition, the POAF group had a lower cumulative survival free of long-term AF than the no-POAF group (P < .001). In competing risk regression, POAF was an independent predictor of long-term newly developed AF (hazard ratio 4.99, 95% CI 1.68-14.84, P = .004). Cumulative survival free of death was worse in patients with POAF (P = .01).nnnCONCLUSIONSnNew-onset POAF was shown to be a predictor of long-term newly developed AF in CABG patients. The results of this study suggest that patients who develop POAF should undergo strict surveillance and routine screening for AF during follow-up after surgery.

The trends of atrial fibrillation-related hospital visit and cost, treatment pattern and mortality in Korea: 10-year nationwide sample cohort data

Background and Objectives The change of in-hospital and out-hospital treatments, and hospital costs for atrial fibrillation (AF) were not well known in rapidly aging Asian countries. This study is to examine the trends of AF management and outcomes in Korea. Subjects and Methods In the sample cohort from Korean National Health Insurance Data Sample Cohort (K-NHID-Sample Cohort) from 2004 through 2013, we identified patients with AF and hospital visit records using Korean Classification of Diseases, 6th Revision (KCD-6). Hospital cost, prescribed medications, radiofrequency catheter ablation (RFCA), morbidity and mortality were identified. Results AF-related hospitalization and outpatient clinic visits increased by 2.19 and 3.06-fold, respectively. While the total cost increased from 3.6 to 11.3 billion won (p<0.001), the mean cost per patient increased from 0.68 to 0.83 million won (p<0.001). Although the mean CHA2DS2-VASc score increased from 3.5 to 4.4 in the total AF population, the proportion of patients who receive anticoagulation therapy with warfarin showed no significant change for the decade. The proportion of hospitalization for RFCA was increased (0.4% to 1.1%, p<0.001). All-cause mortality (6.7% to 5.0%), cardiovascular mortality (1.4% to 1.1%) and stroke-related death (1.3% to 0.8%) showed a modest decrease from 2004 to 2013. Conclusion During the last decade, AF-related hospitalization and outpatient clinic visits have increased with the increase of many other comorbidities, whereas the rate of anticoagulation did not improved. Although mortality in patients with AF showed a modest decrease from 2004 to 2013, proper anticoagulation therapy is warranted for the improvement of public health.

CHA2DS2-VASc Score (Congestive Heart Failure, Hypertension, Age ≥75 [Doubled], Diabetes Mellitus, Prior Stroke or Transient Ischemic Attack [Doubled], Vascular Disease, Age 65-74, Female) for Stroke in Asian Patients with Atrial Fibrillation: A Korean Nationwide Sample Cohort Study

Background and Purpose— The CHA2DS2-VASc stroke score (congestive heart failure, hypertension, age ≥75 (doubled), diabetes mellitus, prior stroke or transient ischemic attack (doubled), vascular disease, age 65–74, female) is used in most guidelines for risk stratification in atrial fibrillation (AF), but most data for this score have been derived in Western populations. Ethnic differences in stroke risk may be present. Our objective was to investigate risk factors for stroke in AF and application of the CHA2DS2-VASc score in an Asian AF population from Korea. Methods— A total of 5855 oral anticoagulant–naive nonvalvular AF patients aged ≥20 years were enrolled from Korea National Health Insurance Service Sample cohort from 2002 to 2008 and were followed up until December 2013. Results— The incidence rates (per 100 person-years) of ischemic stroke were 3.32 in the total population, being 0.23 in low-risk (CHA2DS2-VASc score 0 [male] or 1 [female]) and 4.59 in high-risk patients (CHA2DS2-VASc ≥2). Incidence rates of ischemic stroke or the composite thromboembolism end point showed a clear increase with increasing CHA2DS2-VASc score. On multivariable analysis, significant associations between CHA2DS2-VASc risk factors and ischemic stroke were observed; however, the significance of vascular disease or diabetes mellitus was attenuated after multivariate adjustment, and female sex (hazard ratio, 0.73; 95% confidence interval, 0.64–0.84) had a lower risk of ischemic stroke than males. Patients who were categorized as low risk consistently had an event rate <1% per year. Conclusions— The performance of CHA2DS2-VASc score in Asians is comparable with that in Western populations. The score shows good performance in defining the truly-low-risk AF patients for stroke/thromboembolism.

Prolonged PR Interval Predicts Clinical Recurrence of Atrial Fibrillation After Catheter Ablation

Background A prolonged PR interval is known to be a poor prognostic factor in cardiovascular disease. The aim of this study was to investigate the association between PR interval and clinical outcome in patients undergoing radiofrequency catheter ablation (RFCA) of atrial fibrillation (AF). Methods and Results We prospectively included 576 patients with AF (75.5% male, 57.8±11.6 years old, 68.8% paroxysmal AF) who underwent RFCA. We analyzed preprocedural sinus rhythm ECGs obtained in the absence of antiarrhythmic drug, and all enrolled patients were categorized into 4 groups based on the quartile values of the PR interval (166, 182, and 202 ms), and were analyzed according to the left atrium (LA) volume (CT; Computed tomography), LA voltage (NavX), and clinical outcome of AF ablation. Based on quartile value of PR interval, the highest quartile of PR interval (Q4; PR ≥202 ms) was oldest (P<0.001), and most likely to have persistent AF (P<0.001) and hypertension (P=0.013) compared with the other groups. However, there was no significant difference in LA conduction velocity and atrial effective refractory period. Q4 had the greatest LA dimension (P<0.001) and volume index (P<0.001), and lowest LA appendage‐emptying velocity (P<0.032) and LA voltage (P<0.001) compared with the others. For 13.1±7.5 months, the classification based on the PR interval was a significant predictor of AF recurrence after RFCA of AF (HR=1.969, 95% CI 1.343 to 2.886, P=0.001). Conclusions The PR interval was closely associated with advanced LA remodeling due to AF, and had a noninvasive significant predictive value of clinical recurrence of AF after RFCA.

Pulmonary vein reconnection predicts good clinical outcome after second catheter ablation for atrial fibrillation

AimsnAlthough electrically reconnected pulmonary veins (PV) are the main mechanism of atrial fibrillation (AF) recurrence, PV isolation (PVI) is well-preserved in certain patients who undergo a repeat procedure. We explored the association between PV reconnection and clinical outcomes after a second ablation.nnnMethods and resultsnThis observational cohort study included 143 patients (79.0% male, 56.1 ± 10.0 years old, 65.0% paroxysmal AF) who underwent a second procedure. Pulmonary vein isolation was well-maintained in 52 patients (PVP- group, 36.4%), although the remaining 91 patients showed PV reconnection (PVP+ group). After confirming PVI, we mapped non-PV triggers and conducted trigger ablation or additional linear ablation at redo-procedures. The proportion of females was higher (P = 0.030), and redo-ablation timing after the de novo procedure was later (P = 0.039) in the PVP- group than in the PVP+ group. Additional linear ablations were more likely to be performed in the PVP- group (90.4 vs. 61.5%, P < 0.001). During the 18.4 ± 10.2 month follow-up after the redo-ablation, the PVP+ group showed a lower clinical recurrence rate than the PVP- group (log-rank P = 0.011). The number of reconnected PVs was independently associated with a lower recurrence of AF after the redo-ablation in the total study population (HR 0.56, 95% CI 0.34-0.95, P = 0.032), particularly for patients with paroxysmal AF (HR 0.41, 95% CI 0.19-0.87, P = 0.021).nnnConclusionnAmong patients who underwent redo-AF ablation, those with more PV reconnections showed better clinical outcomes than those with fewer PV reconnections. The mechanism of AF recurrence might be different in patients with lower numbers of PV reconnections during redo-procedures.

CHA2DS2-VASc Score for Identifying Truly Low-Risk Atrial Fibrillation for Stroke: A Korean Nationwide Cohort Study

Background and Purpose— As the threshold of stroke risk for initiating oral anticoagulants is lowered after the introduction of the nonvitamin K antagonist oral anticoagulants, the focus of stroke prevention in patients with nonvalvular atrial fibrillation has shifted away from predicting high-risk patients toward initially identifying patients with a truly low risk of ischemic stroke, who do not need antithrombotic therapy. We tested the predictive ability of the congestive heart failure, hypertension, age ≥75, diabetes mellitus, prior stroke or transient ischemic attack (doubled; CHADS2), congestive heart failure, hypertension, age ≥75 (doubled), diabetes mellitus, prior stroke or transient ischemic attack (doubled), vascular disease, age 65 to 74, female (CHA2DS2-VASc), and Anticoagulation and Risk Factors in Atrial Fibrillation (ATRIA) risk stratification schemes in oral anticoagulants naive patients with atrial fibrillation in a Korean nationwide sample cohort. Methods— From January 2002 to December 2008, a total of 5855 oral anticoagulant naive patients with nonvalvular atrial fibrillation aged ≥20 years were enrolled from Korea National Health Insurance Service-Sample Cohort database and were followed-up until December 2013. Results— At baseline, the proportions categorized as low risk using CHADS2, CHA2DS2-VASc, and ATRIA risk stratification schemes were 1049 (17.9%), 860 (14.7%), and 3280 (56.0%), respectively. During follow-up, the low-risk category using CHADS2, CHA2DS2-VASc, and ATRIA scores was retained in 811 (13.9%), 667 (11.4%), and 2729 (46.6%) patients, respectively. Rates of ischemic stroke (100 person-years) in the low risk categories of CHADS2, CHA2DS2-VASc, and ATRIA scores were 0.42, 0.26, and 1.43, respectively. CHA2DS2-VASc had the best sensitivity (98.8% versus 85.7% in CHADS2 and 74.8% in ATRIA) and negative predictive value (98.8% versus 95.3% for CHADS2 and 93.7% for ATRIA) for the prediction of stroke incidence and was best for the prediction of the absence of ischemic stroke during 5 years of follow-up (odds ratio, 16.4 [95% confidence interval, 8.8–30.8]). Conclusions— The CHA2DS2-VASc score shows good performance in defining truly low-risk Asian patients with atrial fibrillation for stroke compared with CHADS2 and ATRIA scores.

Associations of Abdominal Obesity and New‐Onset Atrial Fibrillation in the General Population

Background Higher height and weight are known to be associated with higher risk of atrial fibrillation (AF); however, whether the risk of AF is related to abdominal obesity is unclear. Methods and Results We studied 501 690 adults (mean age: 47.6±14.3 years; 250 664 women [50.0%]) without baseline AF in the National Sample Cohort released by the National Health Insurance Service in Korea. Body mass index (underweight defined as <18.5; normal, 18.5 to <25.0; overweight, 25.0 to <30.0; and obese, ≥30.0) and waist circumference (abdominal obesity defined as ≥90 cm for men and ≥80 cm for women) were evaluated. During a mean follow‐up of 3.9±1.3 years, 3443 participants (1432 women [41.6%]) developed AF. In multivariable models adjusted for clinical variables, the AF risk of underweight, overweight, and obese individuals increased by 21% (95% confidence interval, 1.01–1.45, P=0.043), 14% (95% confidence interval, 1.06–1.23, P<0.001), and 52% (95% confidence interval, 1.30–1.78, P<0.001), respectively, compared with those with normal body mass index. AF risk with confounder‐adjusted hazards for abdominal obesity was 18% (95% confidence interval, 1.10–1.27, P<0.001). The increased AF risk was present in abdominally obese individuals regardless of body mass index except for the obese group. In subgroup analysis, abdominal obesity by waist circumference conferred increased risk of new‐onset AF, particularly in participants without comorbidities. Conclusions Abdominal obesity is an important, potentially modifiable risk factor for AF in nonobese Asian persons. These data suggest that interventions to decrease abdominal obesity may reduce the population burden of AF.

Advanced Left Atrial Remodeling and Appendage Contractile Dysfunction in Women Than in Men Among the Patients With Atrial Fibrillation: Potential Mechanism for Stroke

Background The risk of stroke imposed by atrial fibrillation (AF) is significantly greater in women than men; however, the mechanism remains elusive. We hypothesized that left atrial (LA) remodeling and poor contractile function of LA appendage (LAA) would be more predominant in women than men among AF patients. Methods and Results A total of 579 AF patients (216 women vs age‐, AF type–, and incidences of heart failure, hypertension, diabetes mellitus, stroke or transient ischemic attack, and vascular disease–matched 363 men, 61.3±10.2 years old, 70.1% paroxysmal AF) who underwent AF catheter ablation were included. Sex differences in LA volume index (LAVI) and LAA emptying flow velocity (FV) were analyzed in risk factor 0, 1, and ≥2 groups, according to their CHA 2 DS 2‐VASc scores beyond sex category. LAA‐FV was more significantly reduced in women with risk factor ≥2 than in men of the same risk group (P=0.022). Women showed greater LAVI than their male counterparts in the risk factor ≥2 group (P<0.001). The majority of female patients with a history of stroke had a large LAVI and low LAA‐FV (P<0.001); however, no such distribution was observed in men (P=0.596). LA volume index (odds ratio [OR], 1.038; 95% CI, 1.003–1.075, P=0.035) or LAA‐FV (OR, 0.976; 95% CI, 0.952–0.999; P=0.047) was significantly associated with a history of stroke in women. Conclusions More‐extensive LA remodeling and deterioration in LAA function were noted in women than in men with high calculated risk of stroke in AF.