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Biomedical subjects

Sirin Apiyasawat

Publications and source records attributed to Sirin Apiyasawat.

14 recordsLinked to original sources
PubMed2006

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.

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PubMed2006

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.

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PubMed2006

Limited utility of interatrial block in predicting ischemia on coronary angiography in patients with suboptimal exercise performance.

INTRODUCTION: Interatrial block (P waves > or = 110 ms) is thought to be associated with underlying myocardial ischemia during exercise but has not been extensively investigated in patients with suboptimal or borderline exercise tolerance tests (< 3 min exercise). We utilized coronary angiography to assess the relationship of both, the resting baseline and exercise induced increase in P-wave duration with coronary artery disease among patients who had undergone such tests. METHODS: We prospectively identified 51 consecutive patients with interatrial block who had coronary artery disease and hypertension but not atrioventricular valvular heart disease, and had undergone coronary angiography to evaluate myocardial ischemia after a suboptimal exercise tolerance test. A control group of 64 consecutive exercise tolerance test patients with similar preliminary characteristics but without interatrial block at rest was used for comparison. Patients from both groups were then appraised for significant obstructive lesions (> 70%) on coronary angiography that were suggestive of myocardial ischemia. RESULTS: Obstructive coronary artery lesions suggestive of myocardial ischemia were more frequent among interatrial block patients but this was not statistically significant (p=0.25). However, change in P-wave duration of > 20 ms occurred more frequently in interatrial block patients in the presence of a positive exercise tolerance test. Among patients without interatrial block at baseline, more patients who developed new interatrial block had significant disease on coronary angiography. CONCLUSION: The utility of using interatrial block toward predicting myocardial ischemia among patients with suboptimal exercise tolerance tests is limited. However, further investigation on the early change in P-wave duration in patients with interatrial block and the development of new interatrial block during exercise could be helpful in optimizing exercise tolerance tests, particularly when borderline or suboptimal.

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PubMed2006

Prospective evaluation of atrial tachyarrhythmias in patients with interatrial block.

INTRODUCTION: Interatrial block (P-wave> or =110 ms) is clinically associated with left atrial enlargement and electromechanical dysfunction as well as atrial tachyarrhythmias. We prospectively evaluated the incidence of such arrhythmias, especially atrial fibrillation among patients with interatrial block over the course of 1 year. METHODS: 118 patients (aged 48 to 104 years; female 56.6%) who had been hospitalized between December 15, 2004 and January 14, 2005 were identified and divided into 3 groups based on their respective baseline electrocardiogram (interatrial block=41 patients, sinus non-interatrial block=51 patients and atrial tachyarrhythmia=24 patients). Patients were subsequently followed for 12 months for pertinent cardiovascular events (heart failure, peripheral embolism, transient ischemic attacks and stroke), atrial tachyarrhythmias (atrial fibrillation and atrial flutter) and death as endpoints. RESULTS: 19 patients (17.9%) had atrial fibrillation during the 12-month follow-up (sinus non-interatrial block group=4 [9.1%], interatrial block group=12 [29.3%] and atrial tachyarrhythmia group=3 [14.3%]). Coronary artery disease, hypertension, pre-existing atrial fibrillation history, dilated cardiomyopathy, atrioventricular valvular disease and interatrial block (age- and sex-adjusted hazard ratio=4.2; 95% confidence interval 1.2-14.4; p=0.02) were significantly associated with future events of atrial fibrillation. However, logistic regression analysis indicated that interatrial block was not an independent predictor of future atrial fibrillation whereas only history of pre-existing atrial tachyarrhythmias was (hazard ratio=23.6; 95% confidence interval 4.5-121.7; p=0.0002). CONCLUSION: Interatrial block may be associated with atrial fibrillation but in a 12-month period, does not appear to be an independent predictor of future atrial fibrillation. Continued prospective investigation of such a relationship is certainly warranted given its already known consequences.

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PubMed2006

Association of Duke prognostic treadmill scores with change in P-wave duration during exercise tolerance tests in patients with interatrial block and coronary heart disease.

Interatrial block (IAB), as denoted by P waves > or =110 ms in duration, is believed to be associated with underlying ischemia, particularly with that of its principal interatrial conduction pathway, the Bachmann bundle. In this study, the association between Duke prognostic treadmill (DPT) scores and change in P-wave duration in IAB was investigated in patients who underwent cardiopulmonary exercise tolerance tests (CPETTs). Twenty-seven patients with IAB and 42 control patients without IAB on electrocardiography at rest who had evidence of myocardial ischemia on coronary angiography after CPETTs were identified consecutively. P-wave measurements were obtained independently at the beginning of every CPETT stage and also when P-wave changes occurred. Increments in P-wave durations were measured to the nearest 20 ms. DPT scores were calculated for the 2 groups. There was no significant difference between the groups in mean values for DPT scores and for exercise capacity. However, change in P-wave duration in patients with IAB was significantly associated with mean DPT score. As the change in P-wave duration increased, the DPT score was significantly less (p = 0.003). DPT scores were more significant with P-wave changes of >20 ms compared with P-wave changes of < or =20 ms (p = 0.00001). In conclusion, in patients with coronary heart disease and IAB at rest, increases in P-wave durations during CPETTs are inversely associated with DPT scores.

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PubMed2006

Specific electrocardiographic markers of P-wave morphology in interatrial block.

BACKGROUND: Interatrial block (IAB; P waves >/= 110 milliseconds), the conduction delay between the right (RA) and left atrium (LA), is depicted on the electrocardiogram (ECG) as prolonged, often bifid ("notched"), P waves with distinguishable RA and LA components. Although electrophysiologic (EP) studies give some insight on how RA and LA components are depicted on the surface ECG in normal conduction, few if at all any, have conclusively demonstrated this correlation with IAB. Using existing EP knowledge, we investigated if such P-wave markers on bedside ECGs exist in IAB and appraised their utility in IAB recognition. METHODS: We reviewed the medical records of patients admitted to a general hospital from December 1, 2004, to December 15, 2004. Of those, 151 patients had been admitted for nonacute presentations and were screened with 12-lead ECGs. Thirty-eight ECGs were excluded for nonsinus and paced rhythms, severe motion artifact, errors in lead placement, absence of adequate patient identification, and duplicate patient admissions after discharge. The remaining 113 ECGs were then evaluated for IAB. Sixty-three patients who did not have IAB formed the control (group A), whereas of the remaining 50 patients with IAB, 24 who had past ECGs for comparison formed group B1 and 26 without past ECGs formed group B2. Groups were compared for common clinical comorbidities, whereas sensitivity and specificity were calculated for significant P-wave markers. P values were also calculated, with a value of <.05 considered significant. RESULTS: Clinical characteristics of patients in all groups were statistically comparable. Overall, almost all P waves in patients with IAB (groups 1 and 2) appeared "notched" (94%, P < .0001; sensitivity, 75%; specificity, 94% for IAB recognition; positive predictive value, 94%). P-wave RA components were commonly depicted as "domes," whereas their LA counterparts formed "spikes" (48%, P < .0001; sensitivity 96%; specificity, 70% for IAB recognition). When groups B1 and B2 were compared with increased accuracy, more P waves in group B1 were noted to have notches and had easily discernible RA and LA components; often, the RA duration is longer than the LA duration. In addition, more "dome-and-spike" complexes could be determined when past ECGs were present for comparison. These markers could be found on any bedside ECG lead in IAB but were predominant on leads II and V3 to V6. CONCLUSIONS: Specific noninvasive surface markers such as P-wave "dome-and-spike" complexes and "notches" in any lead (predominantly leads II and V3-V6) on the bedside ECG could alert clinicians to measure P waves and so identify IAB.

Adolescent↗
PubMed2006

Potential clinical correlates and risk factors for interatrial block.

BACKGROUND: Interatrial block (IAB; P wave > or =110 ms) denotes a conduction delay between the atria, is strongly associated with atrial tachyarrhythmias, left atrial enlargement, left atrial electromechanical dysfunction, and is a risk for embolism. Despite this, potential risk factors for IAB have not been clearly defined. METHODS: Patients admitted via the Emergency Department for nonacute medical reasons to the nontelemetry general medical floors of a tertiary care general hospital from October to November 2004 were screened for sinus rhythm on electrocardiograms. Four hundred and four patients who met our criteria were then evaluated for IAB on respective electrocardiograms. All patients were subsequently compared for common diseases as well as coronary artery disease (CAD) risk factors and divided into two groups, those with IAB and those without (control). Mean age +/- standard deviation, odds ratios (ORs), 95% confidence intervals (CIs), r values, and p values were calculated. p values <0.05 were considered statistically significant. RESULTS: From the sample (n = 404), 182 patients had IAB (45%; mean age 64.32 +/- 19.27 years; males 51.6%) while 222 did not (control). CAD (OR 3.150, 95% CI 2.05-4.83; p < 0.001, r = 0.3), hypertension (OR 2.918, 95% CI 1.85-4.60; p < 0.001, r = 0.2), diabetes mellitus (OR 2.542, 95% CI 1.62-3.97; p < 0.001, r = 0.1), and hypercholesterolemia (OR 1.823, 95% CI 1.22-2.74; p = 0.004, r = 0.2) were significant risk factors and correlates for IAB. Multivariate analysis using stepwise linear regression revealed these factors as direct correlates of IAB. CONCLUSION: CAD, hypertension, diabetes mellitus and hypercholesterolemia appear to be risk factors for IAB in general hospital patients admitted for nonacute reasons. Considering the known sequelae of IAB, awareness of its associations with such risk factors could be important for patient risk stratification.

Adolescent↗
PubMed2006

Optimal P-wave duration for bedside diagnosis of interatrial block.

BACKGROUND: Interatrial block (IAB; P wave > or = 110 ms) is highly prevalent and associated with atrial tachyarrhythmias, left atrial electromechanical dysfunction and is a potential risk for embolism. Investigators have often used different parameters for P-wave duration to define IAB, and this causes confusion further adding to clinician ignorance of IAB. We therefore appraised the mode P-wave duration in IAB and evaluated the sensitivity and specificity of using previously used durations. METHODS: We prospectively evaluated 225 electrocardiograms (ECGs) of patients at a tertiary care general hospital for P-wave duration. Of these, 49 were excluded because of severe motion artifact, errors in lead placement, absence of adequate patient identification, and atrial flutter or fibrillation. Mean, standard error of mean (SEM), standard deviation (SD), mode P-wave duration, specificity, and sensitivity were calculated of the remaining 176 ECGs. RESULTS: From the sample (N = 176; ages 15-95 years; mean +/- SD = 69.15 +/- 16.53 years, female 50.3%), measured P-wave durations ranged from 50 ms to 230 ms (mean +/- SD = 113.75 +/- 30.56 ms, SEM 2.30 ms). 96 patients (54.55%) showed IAB (P wave > or = 110 ms) with the mode P-wave duration being 120 ms. Sensitivity and specificity of using P wave > or = 110 ms is 100% and 88.9%, respectively (accuracy 94.31%), while P wave > or =130 ms yielded 64% and 100%, respectively (accuracy 82.38%). CONCLUSIONS: Mode P-wave duration in IAB is 120 ms, and thus, for all practical reasons, it may be used to clinically diagnose IAB using ECGs recorded at the bedside at 25 mm/s with 10 mm/mV standardization.

Adolescent↗
PubMed2005

Evidence supporting a new rate threshold for multifocal atrial tachycardia.

BACKGROUND: Exacerbation of chronic obstructive pulmonary disease (COPD) is overwhelmingly represented among patients presenting with multifocal atrial tachycardia (MAT) and has been used as a paradigm for such patients. The quasidiagnostic tachycardia threshold for MAT is conventionally set at 100 beats/min. Nevertheless, this threshold has not been demonstrated to be optimal. HYPOTHESIS: Using COPD as a paradigm for MAT, clinical experience led to the hypothesis that MAT with a tachycardia threshold < 100 beats/min could be more closely associated with COPD exacerbation. METHODS AND RESULTS: We reviewed 60 consecutive patients with multifocal atrial arrhythmia (MAA) at any heart rate and found a better association between the incidence of COPD exacerbations and MAT using a tachycardia threshold of 90 beats/min (p = 0.00036) than when using a threshold of 100 beats/min (p = 0.515). CONCLUSION: The rate threshold of MAT should be reduced from 100 to 90 beats/min.

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PubMed2005

Interatrial block during exercise tolerance tests as an additional parameter for the diagnosis of ischemic heart disease.

INTRODUCTION: Interatrial block (IAB; P-wave duration, >or=120 milliseconds) is associated with increases of left atrial pressure. We studied the use of IAB during exercise tolerance test (ETT) in diagnosis of ischemic heart disease. METHOD: Exercise tolerance tests were performed in 149 patients (mean age, 50 years; male, 60.4%). P-wave duration was measured at rest, at each stage of exercise using the Bruce protocol, and in recovery. As clinically indicated, 71 patients subsequently underwent nuclear stress test and/or catheterization. The evidence of ischemia (EOI) was considered present according to the more definite test, that is, catheterization over nuclear stress test over ETT. RESULTS: Among patients who did not have IAB at rest (n=115), 63 patients (54.7%) developed IAB during the ETT. The incidence of IAB during the ETT was higher in patients with EOI than patients without EOI (88.9% vs 51.9%, P=.03). When IAB during the ETT and positive ETT were used together to detect EOI, they were more accurate (86.1% vs 81.7%) than the ETT alone. Among patients with IAB at rest (n=34), patients with EOI had a higher incidence of P-wave duration increase of more than 20 milliseconds during the recovery period than patients without EOI (100% vs 21.8%, P=.015). When using P-wave duration increase of more than 20 milliseconds during the recovery period in conjunction with positive ETT, the sensitivity in detecting EOI was higher than using the ETT alone (100% vs 0%), but the specificity was worsened (68.8% vs 84.4%). CONCLUSION: New IAB and worsening of IAB during ETT appeared in patients with ischemic heart disease and may be used as additional parameters for the ETT interpretation.

Adult↗
PubMed2005

Correlation of left atrial size with p-wave duration in interatrial block.

BACKGROUND: Interatrial block (IAB) [P-wave duration > or = 110 ms] is associated with left atrial (LA) enlargement (LAE) and pathophysiologic derangements that result in atrial tachyarrhythmias, LA electromechanical dysfunction, and embolism. However, there has been no study addressing the direct correlation of P-wave duration in IAB and LAE. METHODS: One hundred eighty-one consecutive patients who were admitted to a tertiary care teaching hospital over 5 consecutive days were screened for past transthoracic echocardiogram evaluations and were then matched with ECGs done within 10 days of these echocardiographic investigations. ECGs were evaluated for presence of IAB, and patients were subsequently classified into two groups: control patients and patients with IAB. Patients were also matched for common comorbidities. Mean, SD of age, Pearson correlation coefficient (r), p values, and multivariate and linear regression analyses were analyzed for the investigated variables of LA size, left ventricular hypertrophy (LVH), posterior wall thickness, septal thickness, and P-wave duration. RESULTS: From the sample (n = 66; mean age +/- SD, 71.3 +/- 13.7; female gender, 48.5%), the mean LA size in the control group was 36.7 +/- 4.01 mm and for the group of patients with IAB (n = 38) was 42.2 +/- 7.25 mm (p = 0.004). Linear regression analysis revealed that P-wave duration was significantly correlated with LA size (p = 0.0002, r = 0.606). CONCLUSIONS: Degree of conduction delay in IAB (P-wave duration) is an independent, direct correlate of LAE, and the regression equation (LA size [in millimeters] = 2.47 +/- 0.29 x P-wave duration [in milliseconds]) could be used to estimate LAE.

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PubMed2005

The correlation of left ventricular hypertrophy with the severity of atherosclerosis and embolic events.

OBJECTIVE: The study was undertaken to assess the correlation between the presence and degree of aortic atheroma with degree of Left ventricular (LV) mass index and subsequent clinical outcomes. MATERIAL AND METHOD: The authors studied the clinical profiles of 87 patients with aortic atherosclerosis and controls, who had undergone TEE between 1995 and 2000. RESULTS: Mean LV mass index was 116 gram/m2 in atherosclerosis group compared to 81 gram/m2 in the control group (p < 0.009). In the atherosclerotic group, there was a close correlation between LV mass index score and severity of the plaque in the aortic arch and descending aorta (p < 0.001, 0.001). The presence of large ulcerated plaque had a significant correlation with stroke (p < 0.002). CONCLUSION: 1) LV mass index correlates with the severity of aortic atheroma. 2) Smoking, elevated mean arterial blood pressure and a high LV mass index score are significantly correlated with large ulcerated plaque and stroke. 3) These findings may in part explain the higher cardiovascular risk in patients with increased left ventricular mass.

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