Frequent Premature Contractions Research Articles

Electrophysiological features and catheter ablation of symptomatic frequent premature atrial contractions.

Frequent premature atrial contractions (PACs) are associated with increased risk of atrial fibrillation (AF), stroke, and death. This study aimed to explore the electrophysiological features of PACs with and without inducing AF and to evaluate the effectiveness of catheter ablation for PACs. Thirty-five consecutive patients with symptomatic, frequent, and drug-refractory PACs in the absence of AF (group A) and 35 patients with PACs-induced AF (group B) were enrolled. Coupling intervals (CoIs) of PACs were compared. Premature atrial contractions were mapped by the point-by-point and/or circular mapping technique. Focal ablation or pulmonary vein/superior vena cava isolation was applied as appropriate. A total of 35 ectopic foci were identified in group A. The majority of them were at pulmonary vein (PV) (n = 7), crista terminalis (n = 6), and para-Hisian area (n = 6). In group B, ectopic foci were in left-sided PVs in 21 patients, in right-sided PVs in 13 patients, and in SVC in 1 patient. There was significant difference in CoIs of PACs triggering AF and those from PVs and non-PV areas but without causing AF (362.8 ± 23.0 ms vs. 470.6 ± 60.1 ms vs. 515.6 ± 77.2 ms, P< 0.001). Premature atrial contractions were abolished in 32 of 35 patients from group A and in all patients from group B. At the end of follow-up, 29 patients in group A and 28 patients in group B were free of recurrence (off antiarrhythmic drugs) after the initial ablation (P =0.97). Frequent PACs in the absence of AF were characterized as having their predilection sites and longer CoIs than those inducing AF. Catheter ablation was effective to eliminate symptomatic, frequent, and drug-refractory PACs.

56-77: Adapting the threshold for atrial fibrillation detection in insertable cardiac monitors based on evidence of irregular sinus rhythm

Background: Frequent premature atrial contractions and sick sinus syndrome are primary causes of inappropriate atrial fibrillation (AF) detection in insertable cardiac monitors (ICM). An algorithm was developed to reduce inappropriate AF detection based on adapting the threshold for detection in the presence of irregular RR intervals and p-wave evidence. Methods: The AF detection algorithm in Reveal LINQ ICM looks for evidence of AF based on differences in the pattern of RR intervals over a 2-minute period. The p-wave evidence based algorithm (P-SENSE) reduces evidence for AF detection if p-waves are detected. The adaptive P-SENSE enhancement uses the presence of p-wave evidence during periods of RR irregularity as evidence of the presence of sick sinus or ectopy to adaptively increase the threshold for AF detection. The algorithm was developed using Holter data from the XPECT study which collected two leads of surface ECG and continuously uplinked ICM ECG over a 46 hour period. ICM detections were compared with Holter annotations to compute episode and duration detection performance. Results: Valid Holter recordings were analyzed from the first 56 patients in the XPECT study with a total follow-up duration of 2168 hours (39 hours per patient). True AF was observed in 16 patients, yielding 89 true AF episodes ≥2 minutes and 201 hours of AF. In the nominal (and aggressive) mode of operation, the algorithm correctly identified 97.9% (97.8%) of total AF duration and 99.5% (99.6%) of total sinus or non-AF rhythm duration. The algorithm detected 89% (89%) of all AF episodes ≥2 minutes, and 60% (74%) of detected episodes had AF in the nominal mode of operation. The adaptive P-SENSE algorithm in nominal (or aggressive) mode was able to reduce false detects by 76% (87%) compared to an algorithm without P-SENSE and 56% (63%) compared to the nominal (aggressive) P-SENSE without any loss in true episode detection (Figure).

Electrical PR Interval Variation Predicts New Occurrence of Atrial Fibrillation in Patients With Frequent Premature Atrial Contractions

Atrial fibrillation (AF) is associated with the autonomic nervous system (ANS), and fluctuation of autonomic tone is more prominent in patients with AF. As autonomic tone affects the heart rate (HR), and there is an inverse relationship between HR and PR interval, PR interval variation could be greater in patients with AF than in those without AF. The purpose of this study was to investigate the correlation between PR interval variation and new-onset AF in patients with frequent PACs.We retrospectively enrolled 207 patients with frequent PACs who underwent electrocardiographs at least 4 times during the follow-up period. The PR variation was calculated by subtracting the minimum PR interval from the maximum PR interval. The outcomes were new occurrence of AF and all-cause mortality during the follow-up period.During a median follow-up of 8.3 years, 24 patients (11.6%) developed new-onset AF. Univariate analysis showed that prolonged PR interval (PR interval > 200 ms, P = 0.021), long PR variation (PR variation > 36.5 ms, P = 0.018), and PR variation (P = 0.004) as a continuous variable were associated with an increased risk of AF. Cox regression analysis showed that prolonged PR interval (hazard ratio = 3.321, 95% CI 1.064–10.362, P = 0.039) and PR variation (hazard ratio = 1.013, 95% CI 1.002–1.024, P = 0.022) were independent predictors for new-onset AF. However, PR variation and prolonged PR interval were not associated with all-cause mortality (P = 0.465 and 0.774, respectively).PR interval variation and prolonged PR interval are independent risk factors for new-onset AF in patients with frequent PACs. However we were unable to determine a cut-off value of PR interval variation for new-onset AF.

Electrocardiogram PR Interval Is a Surrogate Marker to Predict New Occurrence of Atrial Fibrillation in Patients with Frequent Premature Atrial Contractions.

The clinical significance of prolonged PR interval has not been evaluated in patients with frequent premature atrial contractions (PACs). We investigated whether prolonged PR interval could predict new occurrence of atrial fibrillation (AF) in patients with frequent PACs. We retrospectively analyzed 684 patients with frequent PACs (> 100 PACs/day) who performed repeated 24-hour Holter monitoring. Prolonged PR interval was defined as longer than 200 msec. Among 684 patients, 626 patients had normal PR intervals (group A) and 58 patients had prolonged PR intervals (group B). After a mean follow-up of 59.3 months, 14 patients (24.1%) in group B developed AF compared to 50 patients (8.0%) in group A (P < 0.001). Cox regression analysis showed that prolonged PR interval (hazard ratio [HR], 1.950; 95% CI, 1.029–3.698; P = 0.041), age (HR, 1.033; 95% CI, 1.006–1.060; P = 0.015), and left atrial (LA) dimension (HR, 1.061; 95% CI, 1.012–1.112; P = 0.015) were associated with AF occurrence. Prolonged PR interval, advanced age, and enlarged LA dimension are independent risk factors of AF occurrence in patients with frequent PACs.

The circadian variation of premature atrial contractions.

The aim of the study was to assess a possible circadian variation of premature atrial contractions (PACs) in a community-based population and to determine if the daily variation could be used to assess a more vulnerable period of PACs in predicting later incidence of atrial fibrillation (AF). We studied 638 subjects between the ages of 55 and 75 years from the Copenhagen Holter Study who underwent up to 48 h electrocardiogram recording. Follow-up on cardiovascular endpoints was performed in 2013 with a median follow-up time of 14.4 years. According to previous studies, two subgroups were studied based on a cut-off point of ≥720 PACs/day termed frequent PACs (n = 66) and not frequent PACs with <720 PACs/day (n = 572). Based on median values, a circadian rhythm could not be demonstrated in the population as a whole and the group without frequent PACs. However, a circadian variation was observed in the group with frequent PACs, who had the fewest PACs/h during the night with a nadir at 6 am and then reaching a peak value in the afternoon at 3 pm. Runs of PACs in all subjects showed a similar circadian variation. Both PACs/h and runs of PACs seemed to follow the daily variation in heart rate. After adjusting for relevant risk factors, the risk of AF was equal in all time intervals throughout the day. Premature atrial contractions showed a circadian variation in subjects with frequent PACs. No specific time interval of the day was more predictive of AF than others.

PRESENTATION AND DISEASE PROGRESSION OF CHILDREN AND ADOLESCENTS EVALUATED FOR ARRHYTHMOGENIC RIGHT VENTRICULAR CARDIOMYOPATHY

PRESENTATION AND DISEASE PROGRESSION OF CHILDREN AND ADOLESCENTS EVALUATED FOR ARRHYTHMOGENIC RIGHT VENTRICULAR CARDIOMYOPATHY

Electrocardiographic profile of adenosine pharmacological stress testing.

Adenosine stress testing in conjunction with radionuclide myocardial perfusion imaging has become a common approach for the detection of coronary artery diseases in patients who are unable to perform adequate levels of exercise. However, specific electrocardiographic alterations during the test have been rarely described. Using a Chinese population, the aim of the present study was to provide a detailed electrocardiographic profile of adenosine stress testing. The study population included 1,168 consecutive outpatients who had undergone adenosine-induced stress myocardial perfusion imaging. Electrocardiographic data during and immediately following the adenosine infusion were collected, and the corresponding myocardial perfusion images were assessed. During adenosine infusion, 174 transient and 47 persistent arrhythmic events occurred in 110 patients (9.42%). Furthermore, frequent premature atrial contractions occurred in 65 individuals and frequent premature ventricular contractions were observed in 73 individuals. Atrioventricular block (AVB) occurred in 75 patients [first degree (I°) AVB, 16; second degree (II°) AVB, 58; third degree AVB, 1), while sinoatrial block occurred in eight patients. ST depression emerged in 69 patients. Patients with a baseline I° AVB had an increased risk of a II° AVB, and patients exhibiting baseline ST depression were more likely to have a further depressed ST segment during the stress test (odds ratio, 28.68 and 5.01, respectively; both P<0.001). Following adenosine infusion, 10 patients (0.86%) exhibited newly occurred arrhythmic events. However, no patient presented with acute myocardial infarction or sudden mortality. In conclusion, the results demonstrated that adenosine infusion was a safe method, despite the relatively high incidence of arrhythmic events. The majority of arrhythmias that occurred during infusion were transient, were reversible with the termination of infusion and did not indicate abnormal perfusion results.

Abstract 17806: The Prognostic Importance of Frequent Premature Atrial Contractions Following Ischemic Cerebrovascular Events

Background: Following ischemic cerebrovascular accident (CVA) or transient ischemic attack (TIA) aggressive risk factor modification is undertaken to reduce the risk of recurrent events. Holter monitoring is advocated to facilitate the detection and treatment of Atrial Fibrillation (AF). Frequent Premature Atrial Contractions (PACs) are associated with the development of AF, but to date it is unknown whether the burden of PACs on Holters is of any prognostic importance following CVA/TIA. Objective: PACs on Holter monitoring may be a marker for recurrent cerebrovascular events post CVA/TIA. Methods: Retrospective analysis was performed on Holters of patients with CVA/TIA enrolled in a prior population based stroke study. Frequent PACs were defined as a rate of PACs ≥ 100 per 24 hours. The primary endpoint was recurrent CVA or TIA. Results: 84 cases (61.0% male) were reviewed. Mean age was 69.7 ± 12.4 years. Mean time to follow-up was 2514.6 ± 91.2 days. The average number of PACs in the frequent group (Hi-PAC, 21 patients) was 1610.8 ± 4541.4 compared with 21.8 ± 27.6 in those with less than 100 PACs (Lo-PAC, 63 patients). There was no statistically significant difference in age, gender, hypertension or diabetes between the two groups. On follow-up there were 20 recurrent events and 33 patients died. In the Hi-PAC group there were 8 (38.1%) recurrent events, and 16 (76.2%) patients died versus 12 (18.8%) and 17 (26.6%) respectively in Lo-PAC group. On Cox regression analysis the Hazard ratio (HR) for recurrent events was 2.75 (95% confidence interval (CI) 1.08 to 7.01). Kaplan Meier curves revealed a statistically significant difference in recurrance rates between the two groups (p &lt; 0.05). There was also a statistically significant difference in overall mortality on Kaplan Meier survival analysis (p &lt; 0.001), and with a hazard ratio on Cox regression analysis of 3.47 (95% CI 1.74 [[Unable to Display Character: &amp;#8211;]] 6.91). There was no significant difference in incidence of MI or AF. Conclusion: Frequent PACs on Holter monitor represent a significant risk factor for both recurrent events and mortality following CVA/TIA. Further prospective studies should be performed to assess whether these patients may benefit from more aggressive anticoagulation, similar to those with AF.

P-wave evidence as a method for improving algorithm to detect atrial fibrillation in insertable cardiac monitors.

Frequent premature atrial contractions and sick sinus syndrome are primary causes of inappropriate atrial fibrillation (AF) detection in insertable cardiac monitors (ICMs). The study aimed to validate an algorithm designed to reduce inappropriate AF detection on the basis of the identification of a single P wave during the cardiac cycle. The original detection algorithm looks for evidence of AF based on differences in the pattern of R-R intervals over a 2-minute period. The improved algorithm reduces evidence for AF detection if P waves are detected. The algorithm was validated by using Holter data, which collected 2 leads of surface electrocardiogram and continuously uplinked ICM electrocardiogram over a 46-hour period. ICM detections were compared with Holter annotations to compute episode and duration detection performance. Valid Holter recordings (8442 hours) were analyzed from 206 patients. True AF was observed in 76 patients, yielding 482 true AF episodes ≥2 minutes in duration and 1191 hours of AF. The algorithm correctly identified 97.8% of the total AF duration and 99.3% of the total sinus or non-AF rhythm duration. The algorithm detected 85% (90% per-patient average) of all AF episodes ≥2 minutes in duration, and 55% (78% per-patient average) of the detected episodes had AF. AF was found in 95% of the detected episodes >1 hour. The improved algorithm reduced inappropriate episodes and duration by 46% and 55%, respectively, while also reducing appropriate episodes and duration by 2% and 0.1%, respectively. An improvement in the ICM algorithm for AF detection incorporating P-wave information substantially reduced inappropriately detected episodes and duration, with minimal reduction in sensitivity for detecting AF.

A rare cause of neonatal bradycardia: Blocked atrial bigeminal beat

Bradycardia is defined as a heart rate below the lowest normal value adjusted for age. It is caused by intrinsic dysfunction, injury to the heart’s conduction system or by extrinsic factors acting on a normal heart and its conduction system (1). Premature atrial contractions (PACs), are a rare cause of bradycardia. A slow heart rate may occur in that the sinus node discharges a PAC that’s blocked before causing the atria to contract (2,3). Herein, we report a newborn with frequent premature atrial contractions in bigeminal pattern. The bradycardiac patient with bradycardia was successfully treated with propafenone. Herein, we present the case of a 10-day-old infant that was referred to our department for bradycardia. A female neonate of 3100 gr and Apgar score of 8/10 at 1/5 minutes was born by normal spontaneous vaginal delivery at 39. gestational weeks. Her physical examination was normal except bradycardia. Pulse rate was 72 bpm, and blood pressure was 68/32 mmHg. Careful review of her electrocardiogram (ECG) revealed that closely coupled bigeminy PACs were blocked at the atrioventricular junction, mimicking severe sinus bradycardia (Figure 1). No significant abnormalities were found on her echocardiogram, and laboratory test results (complete blood count, biochemical panel and brain natriuretic peptide) were normal. Holter ECG monitoring showed a sinus rhythm with very frequent blocked atrial bigeminy, and short runs of atrial tachycardia. Mean heart rate was 83 bpm, while the minimal, and maximal heart rates was 63 bpm, and 98 bpm, respectively. An antiarrhythmic medication (propranolol) was started without any improvement in the antiarrhytmic control. This treatment was stopped and therapy with propafenone (300 mg/m2/d) was initiat-

Long-term ECG monitoring using an implantable loop recorder for the detection of atrial fibrillation after cavotricuspid isthmus ablation in patients with atrial flutter

In patients with atrial flutter who undergo cavotricuspid isthmus ablation, long-term electrocardiographic (ECG) monitoring may identify new onset of atrial fibrillation (AF). To ascertain, through the use of an implantable loop recorder (ILR) with a dedicated AF detection algorithm, the incidence, duration, and burden of new AF in these patients and to develop an optimal postablation ECG monitoring strategy. We enrolled 20 patients with flutter, a CHADS2 score of 2-3, and no prior episode of AF. After cavotricuspid isthmus ablation, we implanted an ILR, which was interrogated routinely; all stored ECGs were adjudicated. During a mean follow-up of 382 ± 218 days, 3 patterns were observed. First, in 11 (55%) patients, stored ECGs confirmed AF at 62 ± 38 days after ablation. Second, in 4 (20%) patients, although the ILR suggested AF, episodes actually represented sinus rhythm with frequent premature atrial contractions and/or oversensing. Third, in 5 (25%) patients, no AF was observed. Episodes <4 hours were associated with low AF burden (<1%) or false detections. The 1-year freedom from any episode of AF >4 and >12 hours was 52% and 83%, respectively. Our data show that many (but not all) patients develop new AF within the first 4 months of flutter ablation. Since external ECG monitoring for this duration is impractical, the ILR has an important role for long-term AF surveillance. Future research should be directed toward identifying the relationship between duration/burden of AF and stroke and improving existing ILR technology.

Prediction of atrial fibrillation after ischemic stroke using P-wave signal averaged electrocardiography

BackgroundAtrial fibrillation (AF) is highly prevalent in patients with ischemic stroke, but the diagnosis is often difficult. MethodsThis study consisted of 68 stroke patients in sinus rhythm without history of AF. All patients underwent P-wave signal-averaged electrocardiography (P-SAECG), echocardiography, 24-h Holter monitoring, and measurement of plasma B-type natriuretic peptide (BNP) concentrations at admission. ResultsAn abnormal P-SAECG was found in 34 of 68 stroke patients. In the follow-up period of 11±4 months, AF developed in 17 patients (AF group). The remaining 51 patients were classified as the non-AF group. The prevalence of atrial late potentials (ALP) on P-SAECG, and the number of premature atrial contractions (PACs) were significantly higher in the AF group than those in the non-AF group (88.2% vs 37.3%; p<0.001, 149±120 vs 79±69; p=0.030, respectively). However, there were no significant differences in age, left atrial dimension, or BNP concentrations between both groups. Cox proportional hazards analysis revealed that the presence of ALP (risk ratio 11.15; p=0.002) and frequent PACs (more than 100/24h) (risk ratio 4.53; p=0.007) had significant correlation to the occurrence of AF. ConclusionsALP may be a novel predictor of AF in stroke patients. P-SAECG should be considered in stroke of undetermined etiology.

Tracking Down Atrial Fibrillation in the Stroke Unit

See related article, p 2689. Optimal treatment after stroke or transient ischemic attack (TIA) requires identification of atrial fibrillation (AF) if it is present. Standard antithrombotic therapy for patients not known to have AF consists of antiplatelet agents such as aspirin or clopidogrel.1 However, antiplatelet therapy is inferior to anticoagulant therapy for secondary stroke prevention in patients with AF.2,3 Therefore, failure to detect underlying AF as a cause of stroke or TIA results in inadequate antithrombotic therapy and an unnecessarily heightened risk of recurrent stroke. Despite the high stakes, diagnosing AF in patients with stroke or TIA can be difficult. A routine 12-lead electrocardiogram will readily identify persistent AF, but AF often takes an asymptomatic and paroxysmal form that eludes detection. In a study of patients with pacemakers or implanted defibrillators, those with new device-detected AF after stroke or TIA manifested this arrhythmia a median of 5 minutes per day, and most had no AF at all on >90% of days.4 Unfortunately, intermittent AF seems to pose the same risk of stroke as sustained AF.5 Recent data indicate that a single period of AF lasting only 6 minutes independently confers a heightened risk of stroke.6 To ensure appropriate antithrombotic therapy for secondary stroke prevention, these elusive forms of AF must be reliably ruled out. In line with …

Blocked Atrial Bigeminy Presenting with Bradycardia

Blocked premature atrial contractions can cause bradycardia by resetting sinoatrial node and prolonging the RR intervals. Herein, we report the management of a patient with frequent premature atrial contractions in bigeminal pattern. The patient presented with symptomatic bradycardia and was successfully treated with propafenone.

A Trial of the Electrogram Guided Catheter Ablation for Long-Lasting Recurrent Atrial Fibrillation Case: Case Report

Introduction: The endpoint of electrical pulmonary vein (PV) isolation is the agreed goal of procedures targeting the PV-left atrial junction in paroxysmal atrial fibrillation (AF). On the other hand, the targets and endpoints of ablation for chronic (persistent and long-lasting) AF are ill-defined. Results: A 69-year-old male with long-lasting AF was referred for catheter ablation. We performed complex fractionated atrial electrogram (CFAE) guided catheter ablation for AF. AF spontaneously terminated after CFAE guided catheter ablation. After which, frequent premature atrial contractions (PACs) occurred and were mapped and successfully ablated. Our endpoint of CFAE guided catheter ablation in patients with chronic AF used to AF termination. Recently, we use isoproterenol (ISP) to induce AF after AF termination even if AF is non-paroxysmal. Isthmus dependent atrial flutter (AFL) was induced by ISP in this case. AFL was terminated by TV-IVC linear ablation. Repeat induction with rapid atrial pacing and high dose ISP failed to re-induce any atrial tachyarrhythmias. This patient remains in sinus rhythm without any atrial arrhythmia recurrent >7 months after this procedure. Conclusions: Repeat AF induction after AF termination during CFAE guided ablation may be useful to unmask remaining atrial tachyarrhythmia substrate which could be successfully ablated and could help minimizing a chance for a redo procedure in patients with long-lasting AF.

Detection of Occult Paroxysmal Atrial Fibrillation in Stroke Patients Using High Resolution Electrocardiography

Background: Paroxysmal atrial fibrillation (AF) is highly prevalent in patients with ischemic stroke, but the diagnosis is often difficult. Methods: This study consisted of 61 stroke patients in sinus rhythm without a history of paroxysmal AF. All patients underwent P-wave signal-averaged electrocardiography (P-SAECG), echocardiography, 24-hour Holter monitoring, and measurement of plasma B-type natriuretic peptide (BNP) concentrations at admission. Results: An abnormal P-SAECG was found in 33 of 61 stroke patients. In the follow-up period of 11±3 months, paroxysmal AF developed in 19 patients (AF group). The remaining 42 patients were divided into non-AF group. An abnormal P-SAECG and frequent premature atrial contractions (PACs, 100 or more/24 hour) were detected more frequently in patients with AF group than non-AF group (89.5% vs 35.7%; p<0.001, 84.2% vs 26.2%; p<0.001, respectively). However, there were no significant differences in age, left atrial dimension, BNP concentrations between both groups. Cox proportional hazards analysis revealed that an abnormal P-SAECG (hazard ratio 21.3; p=0.003) and frequent PACs (hazard ratio 4.6; p=0.046) had significant correlation to the development of paroxysmal AF. Conclusions: An abnormal P-SAECG and frequent PACs may be novel predictors of paroxysmal AF in stroke patients. P-SAECG should be considered in stroke of undetermined etiology.

Dilated Cardiomyopathy With Conduction Disease and Arrhythmia

case presentation: A 48-year-old woman presents with exertional dyspnea and recurrent syncope. One year earlier, a permanent pacemaker was placed after she complained of fatigue and was found to have high-grade atrioventricular block. Now, she has echocardiographic evidence of moderate to severe left ventricular (LV) systolic dysfunction with regional wall-motion abnormalities. Nuclear imaging is notable for heterogeneous myocardial uptake of technetium Tc99m sestamibi, and coronary angiography reveals widely patent epicardial vessels. Multiple episodes of nonsustained ventricular tachycardia (VT) are documented on continuous ECG monitoring. What are the diagnostic considerations for this patient, and what further evaluations are indicated? This patient presents with dilated cardiomyopathy (DCM) with electric instability (DCM+E), which we define as conduction disease and arrhythmia out of proportion to the severity of LV systolic dysfunction. Diverse causes can result in DCM+E and fall into general categories of inflammatory, infectious, hereditary, and infiltrative processes. Cardiac presentation associated with these conditions is distinct from more common causes of DCM such as ischemic heart disease, viral myocarditis, valvular dysfunction, pregnancy, or substance abuse. Clinical features that are suggestive of DCM+E include supraventricular arrhythmias or conduction disease that precedes cardiomyopathy, multiple VT morphologies, and features suggestive of ischemic heart disease (Q waves, regional wall-motion abnormalities, perfusion defects, ventricular aneurysm) in the absence of epicardial stenoses. In this Clinician Update, we focus on the diagnostic approach to patients with DCM+E. Emphasis is placed on diagnoses that are relatively common or for which the clinical management would be impacted significantly by recognition of the underlying cause. Ischemic heart disease may present with conduction disease and a high burden of arrhythmia, especially in the setting of acute myocardial ischemia/infarction. The exclusion of obstructive coronary artery disease is strongly recommended in patients with DCM+E because atherosclerosis is so prevalent, evidence-based treatment is readily available, and the …

Persistent Increase of Cardiac Troponin I in Plasma without Evidence of Cardiac Injury

A 69-year-old man with diabetes mellitus type II, hypertension, dyslipidemia, and prior ischemic strokes presented to the emergency department with complaints of balance difficulties and inability to stand unassisted of 2 weeks’ duration. The patient’s home medication regimen included atenolol, lisinopril, amlodipine, metformin, and glipizide. He is a retired chef and a former smoker (20 pack-years). He has 2 brothers, both of whom had myocardial infarctions in their 50s. The patient’s physical examination was remarkable for frequent premature contractions, left lower extremity weakness, and impaired coordination. His electrocardiogram revealed sinus rhythm with frequent premature ventricular contractions and diffuse nonspecific T-wave abnormalities. Results of a comprehensive metabolic chemistry panel were within the reference intervals except for increases in glucose (158 mg/dL; reference interval, 74–99 mg/dL) and creatinine (1.5 mg/dL; reference interval, 0.7–1.3 mg/dL). The hemoglobin A1c value was 7.4% (reference interval, <6.0%). Cardiac troponin I (cTnI)1 concentrations were increased at 0.27, 0.22, and 0.25 μg/L (Abbott Architect assay; 99th percentile, <0.03 μg/L) over a span of approximately 8 h. The patient was admitted to the cardiology service on the basis of these abnormal results. A transthoracic echocardiogram revealed a preserved left ventricular systolic function with evidence of impaired diastolic filling. A cardiac catheterization evaluation revealed an ulcerated plaque in the left anterior descending artery with >70% stenosis, which was treated with a bare-metal stent. The presenting symptom of balance difficulty failed to resolve after the coronary intervention, and the patient remained unable to stand unassisted. A neurologic evaluation included magnetic resonance imaging, which found no evidence of an acute stroke. He was discharged with a diagnosis of orthostatic hypotension. Three months later, the patient presented to the emergency department with several days of balance difficulty. The initial cTnI value was increased at 0.10 μg/L, prompting admission to the cardiology …

Focal Atrial Fibrillation in Dextrocardia

A 49-year-old woman with dextrocardia and situs inversus underwent catheter ablation of paroxysmal atrial fibrillation (AF). During the electrophysiologic study, AF triggered by frequent premature atrial contractions (PACs) with a short coupling interval exhibiting a "P on T" pattern occurred. Pulmonary vein mapping revealed that those PACs originated from right-sided (anatomic left) or left-sided (anatomic right) pulmonary veins. In this case with mirror-image dextrocardia, the P-wave morphologies in leads I and aVL and the II/III ratio of the P-wave amplitude were helpful for predicting a right- or left-sided pulmonary vein origin.

Frequent Premature Atrial Contractions in Stroke of Undetermined Etiology

Background: The cause of ischemic stroke is undetermined in 15–40% of patients. We studied the association between frequent premature atrial contractions (PAC) and stroke of undetermined etiology. Methods: We retrospectively studied ischemic stroke patients who were consecutively admitted to our department and underwent 24-hour Holter ECG recording including 163 noncardioembolic stroke patients (group A), 24 stroke patients of undetermined etiology (group B), and 37 cardioembolic stroke patients with prior-diagnosed paroxysmal atrial fibrillation (group C). The number of PAC per 24 h and the prevalence of patients with frequent PAC (200 or more per 24 h) were compared between the groups. Results: The number of PAC was significantly larger in groups B and C than in group A. The proportion of patients with frequent PAC was larger in group B (13/24, 54%) and in group C (18/37, 48%) than in group A (32/163, 20%). Conclusion: Our data suggest that frequent PAC should be regarded as a masked type of paroxysmal atrial fibrillation and should be included in one of the causes of cardioembolic stroke.