Transvenous Lead Extraction (TLE) Procedure: Experience from a Tertiary Care Center in Thailand.

BACKGROUND: Transvenous Lead Extraction (TLE) is a standard treatment for some late Cardiac Implantable Electronics Device (CIED) complications. The outcome of transvenous lead extraction procedure in Thailand is not robust. METHODS: A Single-center retrospective cohort of TLE procedures performed at Ramathibodi hospital between January 2008 and December 2020 was studied. RESULTS: There were 157 leads from 105 patients who underwent lead removal procedure during the specified period. Data analysis was performed from 79 TLE patients due to incomplete data and lead explant procedure of the excluded subjects. Mean patients' age was 57.7 ± 18.7 years, with 70.9% male. There were 82 pacemaker leads, 35 ICD leads, and 5 CS leads (mean number of leads were 1.54 ± 0.66 per patient), with mean implanted duration of 87.8 ± 68.2 months. Main indication for TLE was infection-related, which accounted for 67.1% of the cases. Overall clinical success rate was 97.5%. Mean operative time was 163.8 ± 69.5 min. Major complications occurred in 4 patients (5.1%) with one in-hospital mortality from severe sepsis. CONCLUSION: TLE using laser sheath and rotating mechanical sheath for transvenous lead extraction is effective and safe, even outside high-volume center.

Adherence to Anticoagulant Guideline for Atrial Fibrillation Improves Outcomes in Asian Population: The COOL-AF Registry.

Background and Purpose- Guideline adherent oral anticoagulant (OAC) management of patients with nonvalvular atrial fibrillation has been associated with improved outcomes, but limited data are available from Asia. We aimed to investigate outcomes in patients who received guideline compliant management compared with those who were OAC undertreated or overtreated, in a large nationwide multicenter cohort of patients with nonvalvular atrial fibrillation in Thailand. Methods- Patients with nonvalvular atrial fibrillation were prospectively enrolled from 27 hospitals-all of which are data contributors to the COOL-AF Registry (Cohort of Antithrombotic Use and Optimal INR Level in Patients With Non-Valvular Atrial Fibrillation in Thailand). Patients were categorized as follows: (1) guideline adherence group when OAC was given in high-risk or intermediate-risk, but not in low-risk patients; (2) undertreatment group when OAC was not given in the high-risk or intermediate-risk groups; and (3) overtreatment group when OAC was given in the low-risk group or when OAC was given in combination with antiplatelets without indication. Results- A total of 3327 patients who had follow-up clinical outcome data were included. The mean age of patients was 67.4 years and 58.1% were male. The numbers of patients in the guideline adherence group, undertreatment group, and overtreatment group were 2267 (68.1%), 624 (18.8%), and 436 (13.1%) patients, respectively. The overall rate of ischemic stroke, major bleeding, all bleeding, and death was 3.0%, 4.4%, 15.1%, and 7.8%, respectively. Undertreated patients had a higher risk of ischemic stroke and death compared with guideline adherent patients, and overtreated patients had a higher risk of bleeding and death compared with OAC guideline-managed patients. Conclusions- Adherence to OAC management guidelines is associated with improved clinical outcomes in Asian nonvalvular atrial fibrillation patients. Undertreatment or overtreatment was found to be associated with increased risk of adverse outcomes compared with guideline-adherent management.

Fragmented QRS as a Predictor of Appropriate Implantable Cardioverter-defibrillator Therapy.

BACKGROUND: Fragmented QRS (fQRS) has been shown to be a marker of local myocardial conduction abnormalities and a predictor of cardiac events in selected populations. We hypothesized that the presence of a fQRS might predict arrhythmic events in patients who received an implantable cardioverter-defibrillator (ICD), regardless of the indications for implantation. METHODS AND RESULTS: A cohort of 107 consecutive patients (mean age, 53 years; 82% male) who underwent an ICD implantation was studied. We defined fQRS, on a routine 12-lead ECG, as the presence of an additional R wave or notching in the nadir of the S wave in 2 consecutive leads corresponding to a major coronary artery territory. In the presence of bundle branch block, more than 2 notches in the R or S waves in 2 consecutive leads were required to characterize fQRS. Patients were followed for 21.3±23 months for appropriate ICD therapy (antitachycardia pacing and/or shock). ICDs were implanted predominantly in patients with ischemic cardiomyopathy (N=45, 42.1%), followed by Brugada syndrome (N=26, 24.3%). fQRS presented in 42 patients (39.3%). During follow-up, patients with fQRS received more appropriate ICD therapy than those without fQRS (45.2% vs. 10.8%, P<0.0001). After adjustment for covariates, fQRS remained an independent predictor for appropriate ICD therapy (hazard ratio=5.32, 95% confidence interval=2.11-13.37, P<0.0001). CONCLUSION: The presence of fQRS appeared to be directly associated with appropriate ICD therapy.

Ventricular pacing dependency after transcatheter aortic valve replacement: a prospective cohort.

Background: Atrioventricular conduction disturbance occurs in a significant number of patients undergoing transcatheter aortic valve replacement (TAVR). However, not all cases are ventricular pacing-dependent. Thus, we aimed to study the incidence, predictors, and outcomes of new ventricular pacing dependency (VpDep) after TAVR. Methods: We prospectively analyzed 130 consecutive transfemoral TAVR cases performed in Ramathibodi Hospital between 2015 and 2020. Three patients with prior ventricular pacing-dependent on cardiac implantable electronic devices (CIEDs) were excluded. The endpoints were VpDep at 1 month and all-cause mortality at the follow-up period end in 2021. The effects of variables on VpDep and all-cause mortality were evaluated using multivariate binary logistic regression and Cox regression analyses, respectively. First-degree atrioventricular block (AVB) was considered severe when the PR interval was >300 ms. Results: Of the 127 patients [mean age, 81.8 years; 62.2% females; 67.7% balloon-expandable (BE) device], 7 patients (5.5%) had CIEDs implanted before TAVR that were not ventricular pacing-dependent. TAVR was successfully performed in 126 (99.2%) patients. Periprocedural stroke, cardiac tamponade, and major bleeding occurred in 2 (1.6%), 4 (3.1%), and 4 (3.1%) patients, respectively. The VpDep incidence at 1 month was 7.9% (n=10) among all patients and 34.5% among those with CIEDs (n=29). VpDep was more likely to occur in patients with pre-existing right bundle branch block (RBBB) [odds ratio (OR), 21.38; 95% confidence interval (CI): 3.28-139.33; P=0.001] and severe 1st degree or Mobitz I AVB (OR, 14.79; 95% CI: 1.65-132.74; P=0.016). After a mean follow-up of 25.8 months [standard deviation (SD), 21.2 months], death from any cause occurred in 18 patients (14.2%). However, VpDep was not associated with an increased mortality. Conclusions: In this real-world cohort, pre-existing conduction abnormalities were significantly associated with a higher risk of VpDep. Mortality was similar between patients with and without VpDep.

Statement from the Asia Summit: Current state of arrhythmia care in Asia.

On May 27, 2022, the Asia Pacific Heart Rhythm Society and the Heart Rhythm Society convened a meeting of leaders from different professional societies of healthcare providers committed to arrhythmia care from the Asia Pacific region. The overriding goals of the meeting were to discuss clinical and health policy issues that face each country for providing care for patients with electrophysiologic issues, share experiences and best practices, and discuss potential future solutions. Participants were asked to address a series of questions in preparation for the meeting. The format of the meeting was a series of individual country reports presented by the leaders from each of the professional societies followed by open discussion. The recorded presentations from the Asia Summit can be accessed at https://www.heartrhythm365.org/URL/asiasummit-22. Three major themes arose from the discussion. First, the major clinical problems faced by different countries vary. Although atrial fibrillation is common throughout the region, the most important issues also include more general issues such as hypertension, rheumatic heart disease, tobacco abuse, and management of potentially life-threatening problems such as sudden cardiac arrest or profound bradycardia. Second, there is significant variability in the access to advanced arrhythmia care throughout the region due to differences in workforce availability, resources, drug availability, and national health policies. Third, collaboration in the area already occurs between individual countries, but no systematic regional method for working together is present.

Effect of ElectroMagnetic interference from SmartPHone on cardiac ImplaNtable electronic device (EMI-PHONE study).

Background: Smartphone can emit two types of electromagnetic waves, static field and dynamic field. Evidence showed the interference from phones to cardiac implantable electronic devices (CIEDs). The smartphones and CIEDs are reportedly better designed to reduce electromagnetic interference (EMI). Methods: 80 consecutive subjects with CIEDs were recruited and tested for EMI. Subject was tested with three different smartphones (Nokia 3310, Iphone 7, and Samsung 9S). Phone was attached to chest wall at 0 cm at generator site, at atrial lead level, and at ventricular lead level. During the tests, real-time interrogations were performed to detect any EMI from smartphone in standby mode, and during calling-in and out for 30 s. After the tests, post-test interrogations were performed to detect any parameter change. Adverse events including pacemaker inhibition, false ICD shock, CIEDs device malfunction, and urgent electrophysiologist consultations were recorded. Results: 80 subjects (mean age 70.5-year-old, 50% male) recruited in the study, all completed the testing protocol. The most common type of CIEDs tested was pacemaker (N = 56, 70%), followed by ICD (N = 16, 20%), and CRT (N = 8, 10%). Most patients (N = 62, 77.5%) had more than one lead implanted. The mean year of implantation was 5.2±2.8 (devices were implanted from 2008 to 2019). Of all the tests performed, there was no EMI or adverse events observed. Conclusion: Current generation of smartphones has no EMI effect on CIEDs in our study and can be used safely with less concern about adverse events including pacemaker inhibition, inappropriate ICD shock, and CIEDs device malfunction.

Outcome disparities in patients with atrial fibrillation based on insurance plan and educational attainment: a nationwide, multicenter and prospective cohort trial.

BACKGROUND: Atrial fibrillation (AF) is a complex disease. The management of AF requires continuous patient engagement and integrative healthcare. OBJECTIVES: To explore the association between adverse AF-related clinical outcomes and the following two sociodemographic factors: educational attainment and insurance plan. DESIGN: A nationwide, prospective, multicenter, cohort trial. SETTING: National registry of 3402 patients with non-valvular AF in Thailand. PARTICIPANTS: All patients enrolled in the registry, except those with missing information on educational attainment or insurance plan. Finally, data from 3026 patients (mean age 67 years, SD 11.3; 59% male sex) were analysed. PRIMARY OUTCOMES: Incidences of all-cause mortality, ischaemic stroke and major bleeding during the 36-month follow-up period. Survival analysis was performed using restricted mean survival time (RMST) and adjusted for multiple covariates. The levels of the educational attainment were as follows: no formal education, elementary (grade 1-6), secondary (grade 7-12) and higher education (tertiary education). RESULTS: The educational attainment of the majority of patients was elementary (N=1739, 57.4%). The predominant health insurance plans were the Civil Servant Medical Benefit Scheme (N=1397, 46.2%) and the Universal Coverage Scheme (N=1333, 44.1%). After 36 months of follow-up, 248 patients died (8.2%), 95 had ischaemic stroke (3.1%) and 136 had major bleeding (4.5%). Patients without formal education died 1.78 months earlier (adjusted RMST difference -1.78; 95% CI, -3.25 to -0.30; p=0.02) and developed ischaemic stroke 1.04 months sooner (adjusted RMST difference -1.04; 95% CI, -2.03 to -0.04; p=0.04) than those attained a level of higher education. There were no significant differences in RMSTs for all three clinical outcomes when considering the type of health insurance plan. CONCLUSION: Educational attainment was independently associated with all-cause mortality and ischaemic stroke in patients with AF, but adverse clinical outcomes were not related to the types of health insurance in Thailand. TRIAL REGISTRATION NUMBER: Thai Clinical Trial Registration; Study ID: TCTR20160113002.

Mortality risk and temporal patterns of atrial fibrillation in the nationwide registry.

AIMS: Persistent and permanent atrial fibrillation (AF) often occurs in the presence of multiple comorbidities and is linked to adverse outcomes. It is unclear whether the sustained pattern of AF itself is prognostic or if it is confounded by underlying comorbidities. Here, we tested the association between the temporal patterns of AF and the risks of ischemic stroke and all-cause mortality. METHODS AND RESULTS: In a prospective multicenter cohort, 3046 non-valvular AF patients were consecutively enrolled and followed for adverse outcomes of all-cause mortality and ischemic stroke. The risks of both outcomes were adjusted for underlying comorbidities, and compared between the patterns of AF. At baseline, the patients were classified as paroxysmal (N = 963, 31.6%), persistent (N = 604, 19.8%), and permanent AF (N = 1479, 45.6%) according to the standard definition. Anticoagulants were administered in 75% of all patients and 83% of those with CHA2DS2-VASc score ≥2 in males or ≥3 in females. During a mean follow up of 26 (SD 10.5) months, all-cause mortality occurred less in paroxysmal AF (2.5 per 100 patient-years) than in persistent AF (4.4 per 100 patient-years; adjusted hazard ratio [HR] 0.66, 95% CI, 0.46-0.96; P = .029) and permanent AF (4.1 per 100 patient-years; adjusted HR 0.71, 95% CI, 0.52-0.98; P = .036). The risk of ischemic stroke was similar across all patterns of AF. CONCLUSIONS: In this multicenter cohort of AF patients, persistent and permanent AF was associated with higher all-cause mortality than paroxysmal AF, independent of baseline comorbidities. CLINICAL TRIAL REGISTRATION: Thai Clinical Trial Registration; Study ID: TCTR20160113002 (http://www.thaiclinicaltrials.org/show/TCTR20160113002).

Feasibility, efficacy, and safety of radiofrequency catheter ablation for cardiac arrhythmias: a twelve-year experience in Thailand.

BACKGROUND: Radiofrequency catheter ablation (RFCA) is widely accepted as a curative treatment for many types of cardiac arrhythmias. MATERIAL AND METHOD: The authors retrospectively reviewed 1,193 cases (mean age 45, 41% male) performed in the electrophysiology laboratory at Ramathibodi Hospital from 1996 to 2007. Success rate, recurrence rate and complications were analyzed. RESULTS: Ablations of atrioventricular nodal reentrant tachycardia (AVNRT, 428 cases, 35.9%) and atrioventricular reentrant tachycardia (AVRT, 346 cases, 29%) were the most common procedures. The overall success rate and recurrence rate of RFCA were 88.8% and 6.1% respectively. Complications occurred in 50 patients (4.2%) with 1 death (0.08%). RFCA of AVNRT or AVRT rather than other arrhythmias (Odd ratio 11.46, 95% confidence interval 8.14-16.15, p < 0.001) and adult rather than pediatric patients (Odd ratio for age 1.007, 95% confidence interval 1.003-1.011, p < 0.001) were independent predictors for successful RFCA. CONCLUSION: RFCA of cardiac arrhythmia in our institution is safe and effective.

SAMe-TT2R2 score for prediction of suboptimal time in therapeutic range in a Thai population with atrial fibrillation.

INTRODUCTION: International normalised ratio (INR) control is an important factor in patients with non-valvular atrial fibrillation (NVAF) being treated with warfarin. INR control was previously reported to be poorer among Asians compared to Westerners. We aimed to validate the SAMe-TT2R2 score for prediction of suboptimal INR control (defined as time in therapeutic range [TTR] < 65% in the Thai population) and to investigate TTR among Thai NVAF patients being treated with warfarin. METHODS: INR data from patients enrolled in a multicentre NVAF registry was analysed. Clinical and laboratory data was prospectively collected. TTR was calculated using the Rosendaal method. Baseline data was compared between patients with and without suboptimal INR control. Univariate and multivariate analyses were performed to identify variables independently associated with suboptimal INR control. RESULTS: A total of 1,669 patients from 22 centres located across Thailand were included. The average age was 69.1 ± 10.7 years, and 921 (55.2%) were male. The mean TTR was 50.5% ± 27.5%; 1,125 (67.4%) had TTR < 65%. Univariate analysis showed hypertension, diabetes mellitus, heart failure, renal disease and SAMe-TT2R2 score to be significantly different between patients with and without optimal TTR. The SAMe-TT2R2 score was the only factor that remained statistically significant in multivariate analysis. The C-statistic for the SAMe-TT2R2 score in the prediction of suboptimal TTR was 0.54. CONCLUSION: SAMe-TT2R2 score was the only independent predictor of suboptimal TTR in NVAF patients being treated with warfarin. However, due to the low C-statistic, the score may have limited discriminative power.

The association of atrial tachyarrhythmias with isolated atrial amyloid disease: preliminary observations in autopsied heart specimens.

OBJECTIVE: Isolated atrial amyloidosis (IAA) is associated with atrial tachyarrhythmias. However, only a few studies have appraised atrial tachyarrhythmias and atrial depolarization abnormalities in connection with high-grade IAA. We conducted a collaborative retrospective study to assess this association. METHODS: One hundred consecutive autopsied hearts were studied histologically for IAA. To increase the specificity for atrial depolarization abnormalities in this preliminary study, we excluded those specimens with intermediate amyloid involvement, i.e. IAA grades 1 and 2 (grade 0 = absent or trivial deposits; grade 1 = small deposits; grade 2 = moderate deposits; grade 3 = dense, large deposits). We then screened for baseline, premortem electrocardiograms (ECGs) to assess rhythm. In those with sinus rhythm, the P wave axis, duration, dispersion and terminal force in V1 were determined under magnification. RESULTS: Of the 27 premortem ECGs corresponding to the autopsy specimens with grades 3 (sample) or 0 (controls) IAA, 9 showed sinus rhythm, 13 showed atrial fibrillation, 1 showed atrial flutter and 4 were uninterpretable. Fourteen autopsied hearts (52%) were positive for grade 3 IAA. Ten of those had atrial tachyarrhythmias (9 atrial fibrillation and 1 atrial flutter) compared to 4 of the 13 hearts with grade 0 IAA (72 vs. 31%, respectively; p = 0.03). Although there was excellent interobserver agreement using intraclass correlation coefficients, there were no significant differences in P wave measurements among the small number of patients with sinus rhythm for grade 3 versus grade 0 IAA. CONCLUSION: In a collaborative, preliminary, pilot assessment of autopsied hearts for which premortem ECGs were necessarily screened retrospectively, significantly more hearts with high-grade IAA were associated with atrial tachyarrhythmias compared to those with low-grade IAA. A larger study with an appropriately matched autopsy control group is needed to confirm these and previous observations.

Is the presence of mitral annular calcification associated with poor left atrial function?

INTRODUCTION: Mitral annular calcification (MAC) is characterized by calcium and lipid deposition in the annular fibrosa of the mitral valve. MAC is associated with cardiovascular events but little is known of its association with left atrial (LA) function. METHODS: We prospectively obtained 12-lead electrocardiograms (ECGs) and transthoracic echocardiograms (TTE) on patients scheduled for nonemergent echocardiographic assessment at a tertiary care hospital. MAC was graded as 0 = none, 1 = mild, 2 = moderate, 3 = severe. LA linear and volume measurements (stroke volume, LA passive emptying fraction, LA active emptying fraction and LA kinetic energy) were done specifically in addition to commonly measured TTE parameters. RESULTS: From the 124 considered for the study, 72 patients remained (aged 68+/-18 years; 44% male) after excluding those with poor ECG tracings and/or poor TTE images. Eighteen patients had MAC; mild MAC = 14, moderate MAC = 3, severe MAC = 1. When patients with MAC were compared to those without MAC, no significant difference was noted, except for LA linear dimension index (2.1+/-0.4 vs. 1.9+/-0.3 cm/m(2); P = 0.03). For those with mild and moderate MAC, a trend was noted toward lower LA function with increasing MAC severity. In addition, significant differences were noted between those with and without interatrial conduction delay, where those with such delay had significantly impaired LA stroke volume (9.8+/-3 vs. 19.93+/-4 ml; P < 0.0001), LA active emptying fraction (18.83+/-8 vs. 65.71+/-9%; P < 0.0001) and LA total/reservoir fraction (39.54+/-6 vs. 75.1+/-6%; P < 0.0001). CONCLUSIONS: MAC is associated with increase in LA linear dimension on TTE and may be equally represented with lower overall LA function. Further study in a much larger cohort is warranted to delineate these and other potential associations of MAC.

Formulaic quantification of echocardiographic left atrial volume.

INTRODUCTION: The association between increasing severity in abnormal atrial depolarization and left atrial (LA) volume derived by transthoracic echocardiogram (TTE) has been described through the following regression formula: LA end-systolic volume index (LAVI [milliliter]) = 8.0 + 0.2 (P-wave duration [millisecond]) (r = 0.47; P = .0002). However, prospective assessment of this formula has not been validated among inpatients outside the institution where it was first derived. METHODS: We prospectively obtained 12-lead electrocardiograms (ECGs) and TTEs on consecutive inpatients who were scheduled for nonemergent echocardiographic assessment. P waves were assessed independently to the nearest 10 milliseconds for application of the formula with a Bland-Altman plot. P-wave durations were obtained specifically from lead II and also from the any lead that yielded the widest measurement. RESULTS: After excluding those with poor ECG tracing and TTE images, 72 patients were studied. We found a strong formulaic correlation with LAVI by TTE when maximal P-wave measurements were obtained from any ECG lead (r = 0.67; P < .0001) and more so, when restricted only to lead II (r = 0.89; P < .0001). Correlation was strongest when there was no or minimal difference between P-wave measurements in lead II and all other leads (r = 0.84; P < .0001 for no difference vs r = 0.67; P < .0001 for 60-millisecond difference). The Bland-Altman plot showed good agreement of LAVI assessment using the formulaic estimation when compared to TTE measurements derived by Simpson's rule (coefficient of reproducibility for 2 SD equivalent to 8.8% for lead II and 11.4% for any lead). CONCLUSION: There is good agreement and correlation between formulaic estimation and that of TTE for LAVI among inpatients. Such quantification of LA size not only serves as an indirect asset that could perhaps supplement TTE measurements in certain circumstances but also can facilitate risk stratification of patients.

Differences in treadmill exercise tolerance parameters between patients with partial and advanced interatrial depolarization abnormality.

Advanced interatrial block (aIAB) is considerably much less common than partial interatrial block (pIAB), occuring in <2% of the elderly hospitalized population. Less is, therefore, known of the true clinical burden of aIAB, particularly in relation to graded exercise. Therefore, 12 patients with aIAB and 30 patients with pIAB who performed a baseline exercise tolerance test and had a repeat test performed > or = 2 years later were included in the study. Exercise tolerance, echocardiographic findings, and major adverse cardiovascular events were compared. Left atrial size progressed at a significantly faster rate in those with aIAB. In addition, Duke Prognostic Treadmill scores were significantly lower on follow-up in those patients with aIAB. Overall, patients with aIAB had significantly greater left atrial size (48.3 +/- 9 vs 42.8 +/- 4 mm, p < 0.01) and significantly lower Duke Prognostic Treadmill scores than those with pIAB (-0.2 +/- 5 vs 4.1 +/- 4, p < 0.05). There were, however, no significant differences in the occurence of major adverse cardiovascular events. In conclusion, left atrial size progressed at a significantly faster rate but Duke Prognostic Treadmill scores were significantly lower in those with aIAB compared with patients with pIAB after > or = 2 years of follow-up. Further study is required to determine whether patients with aIAB require follow-up echocardiography and/or exercise tolerance tests for optimal risk stratification.

High prevalence of widened P waves among pediatric patients in 2 separate hospitals.

INTRODUCTION: In adults, P waves of 110 milliseconds or longer are often associated with significant disease. In the pediatric population, however, cutoffs for P-wave durations are naturally lower but could vary physiologically with age because of increasing heart mass. We appraised if age-proportionate increase in P-wave duration does indeed occur in both hospitalized infants and children and also investigated the prevalence of widened P-wave durations using currently accepted "normal" cutoffs (

Angiographic localization of potential culprit coronary arteries in patients with interatrial block following a positive exercise tolerance test.

Interatrial block (IAB), denoted by P waves > or =110 ms, is believed to be associated with underlying ischemia, particularly with that of its principal interatrial conduction pathway, the Bachmann bundle. We investigated if there is an angiographic association of IAB on electrocardiograms at rest in patients who underwent cardiac angiography after a positive exercise tolerance test (ETT) result. Twenty-seven patients with IAB and 42 control patients without IAB on electrocardiograms at rest who had evidence of ischemia on cardiac angiography after ETT were identified. Coronary vessels that were angiographically most significantly stenosed (> or =70% occlusion indicating stenosis) were noted for statistical comparison (a p value <0.05 was considered statistically significant). Among patients with IAB, the right coronary artery was the predominant vessel to be affected, with > or =70% narrowing compared with the left, inclusive of the left main, left circumflex, obtuse marginal, and diagonal coronary arteries (58% vs 23%, p = 0.03). Right coronary artery lesions in patients with IAB were mostly in the proximal and mid portions (54% vs 25% for the entire left coronary artery, p = 0.02). No such difference was noted in control subjects. In conclusion, in patients with IAB at rest who have coronary heart disease, the right coronary artery is predominantly more significantly affected.

Association of myocardial ischemia and coronary angiographic lesions with increased left atrial dimension during exercise tolerance tests among patients without known coronary heart disease.

The association between left atrial (LA) dilation and fundamental exercise parameters has not shared equal extensive investigation as its clinical correlate, interatrial block (IAB; P waves > or =110 ms). We prospectively identified 94 consecutive patients with LA dilation on 2-dimensional transthoracic echocardiography but without atrioventricular valvular disease, hypertension, or coronary artery disease who had undergone coronary angiography after exercise tolerance tests (ETTs) for assessment of new coronary artery disease. Duke prognostic treadmill (DPT) scores were calculated and exercise capacity was expressed as METs of workload achieved. We appraised the cohort for common co-morbidities, IAB on electrocardiography at rest, and exercise-induced P-wave increments (divided into 20-ms quintiles). IAB (67% vs 34%, p = 0.002) and increased LA dimension (48 +/- 6 vs 45 +/- 5 mm, p = 0.01) were associated in patients with >70% coronary artery diameter stenoses and were equally reflected by positive ETT results (79.5% vs 20%, p <0.001), decreased METs (11.43 + [-0.60 x LA size (millimeters)], r(2) = 0.04), and lower DPT scores (35.23 + [-0.70 x LA size (millimeters)], r(2) = 0.73). Incremental P-wave change was associated with lower METs and DPT scores but with positive ETT results and significant coronary artery stenoses (p for trend <0.001). LA dimension was largest in the highest quintile (>60 ms) of P-wave change (p for trend <0.001). In conclusion, increased LA dimension is significantly associated with myocardial ischemia during ETT and is reflected by lower METs and DPT scores and a higher incidence of coronary artery diameter stenoses >70% in patients matched by age-, gender-, and LA size without preexisting coronary artery disease.

Frequency of interatrial block in patients with sinus rhythm hospitalized for stroke and comparison to those without interatrial block.

Interatrial block (IAB; P wave > or =110 ms) is a potent correlate of left atrial (LA) enlargement and electromechanical dysfunction and a strong predictor of atrial tachyarrhythmias, in particular, atrial fibrillation. Although these associations increase its risk for embolism, i.e., cardioembolic stroke, such a phenomenon has been inadequately investigated. We investigated 85 general hospital patients who had been admitted to the neurologic unit between January 2003 and December 2004 for embolic stroke. Of those, 66 patients who had electrocardiograms that showed sinus rhythm were evaluated for IAB and categorized as those with IAB and those without (controls). Medical records were then reviewed for common co-morbidities and stroke risk factors, high-resolution carotid artery Doppler ultrasonographic study reports, and 2-dimensional echocardiograms obtained during the current admission for embolic stroke; 40 patients (61%) had IAB. There was a 55% prevalence of LA enlargement (diameter in the parasternal long-axis view > or =40 mm, p <0.001). LA thrombi and/or spontaneous contrast ("smoke") were noted on echocardiograms in 6 patients with IAB (15%) but not in any of the controls (p = 0.038). Five of those 6 patients with such LA thrombi had dilated LA cavities. In conclusion, IAB could be a risk for embolic stroke due to its known sequelae of LA dilation and electromechanical dysfunction that predispose to thrombosis. If prospective studies prove this to be so, the need for anticoagulation use in such patients should be investigated.

Association of atrial fibrillation in patients with interatrial block over prospectively followed controls with comparable echocardiographic parameters.

Interatrial block (IAB) (P wave >or=110 ms) is a potential risk of atrial fibrillation (AF). However, few investigations have assessed the relevance of echocardiographic parameters, particularly the contribution of its known correlate, left atrial enlargement in this regard. We identified 32 consecutive patients with comparable echocardiographic parameters, such as left atrial dimension and left ventricular ejection fraction. Patients were evaluated for IAB and followed for 15 months for cardiovascular events (heart failure, transient ischemic attacks, and stroke), atrial tachyarrhythmias (AF/atrial flutter), and death. Preexisting AF and IAB (p = 0.02) were significantly associated with future AF events. However, logistic regression analysis indicated that IAB was not an independent predictor of future AF, only preexisting atrial tachyarrhythmias was (hazard ratio 39.5, 95% confidence interval 2.7 to 576.3, p = 0.007). In conclusion, in patients with comparable echocardiographic parameters, such as left atrial size and left ventricular ejection fraction, IAB remained associated with AF after a 15-month follow-up. Additional investigation is needed to confirm the extent of the association.

Quantitative estimation of left atrial linear dimension on a transthoracic echocardiogram using an electrocardiographic formulaic assessment.

A proportionate and incremental association between left atrial (LA) dilatation on a transthoracic echocardiogram (TTE) and increasing severity in abnormal atrial depolarization can be described by the regression formula: LA dimension in parasternal long-axis view (in millimeters) = 2.47 + 0.29 [P-wave duration (in milliseconds)]. However, prospective testing of this formula for LA quantification with comparison to other TTE indexes is lacking. We prospectively obtained 12-lead electrocardiograms for 72 consecutive patients before individual, nonemergent TTE assessment. P waves were assessed independently to the nearest 10 ms for application of the formula with a Bland-Altman plot. P-wave durations were obtained specifically from lead II and also from any lead that yielded the widest measurement. There was a strong formulaic correlation with LA measurement by TTE (p <0.00000001; r = 0.662), irrespective of electrocardiographic lead used. However, as the measurement difference increased between that in any lead and lead II, correlation strength increased. Correlation was not significantly affected by commonly measured electrocardiographic and TTE indexes, such as, PR interval, QRS complex, and left ventricular end-diastolic as well as systolic dimensions, after adjustment for these variables. Moreover, when the P-wave axis remained within the normal range, the correlation strength increased. The Bland-Altman plot also showed good agreement of LA dimension assessment between formulaic estimation and TTE measurement. In conclusion, there is good agreement and correlation between formulaic estimation and that of TTE for measurement of LA linear dimension. The LA regression formula is an indirect asset that could perhaps supplement LA quantification on TTE in certain circumstances.