Lone Atrial Fibrillation Group Research Articles

Decreased left atrial strain parameters are correlated with prolonged total atrial conduction time in lone atrial fibrillation

To investigate left atrium (LA) strain properties of patients with lone atrial fibrillation (LAF) and to assess relationships between LA strain parameters and total atrial conduction time measured with tissue Doppler imaging (PA-TDI). The study population consisted of 53 patients with LAF. The control group was comprised of 50 normal volunteers. Conventional echocardiography indices were measured. Mitral annular velocities and PA-TDI were assessed with TDI. Two-dimensional speckle-tracking echocardiography (2D-STE) was used to assess LA segmental strain and strain rate. Compared with the control group, PA-TDI was significantly prolonged and LA myocardial Ss, SRs, Sa, and SRa were significantly decreased in the LAF group (all P < 0.001). In the control group, LA myocardial Ss (γ = -0.486, P < 0.01), SRs (γ = -0.436, P < 0.01), and Sa (γ = -0.360, P < 0.05) were correlated negatively with PA-TDI. LA myocardial SRa (γ = 0.377, P < 0.01) was correlated positively with PA-TDI. In the LAF group, LA myocardial Ss (γ = -0.429, P < 0.01), SRs (γ = -0.468, P < 0.01), and Sa (γ = -0.380, P < 0.05) were also correlated negatively, and SRa (γ = 0.390, P < 0.01) was correlated positively, with PA-TDI. Multivariate logistic regression identified PA-TDI as the only predictor of AF onset (OR 1.39; 95 % CI 1.02-1.54; P < 0.01). LA strain parameters were decreased and PA-TDI was prolonged in patients with LAF. Structural remodeling of the LA, assessed by 2D-STE, was correlated with electrical remodeling, determined by PA-TDI. Prolonged PA-TDI was independently associated with AF onset.

The relationship between erectile dysfunction and paroxysmal lone atrial fibrillation

Endothelial dysfunction plays a major role in erectile dysfunction (ED). Atrial fibrillation (AF), regardless of subtype, is associated with a prothrombotic state, which is related to endothelial dysfunction. In this study, we aimed to determine whether AF is an independent risk factor for ED. A total of 50 patients diagnosed with paroxysmal lone AF and 80 age-, gender-, and body mass index-matched controls without AF who admitted to outpatient clinics at a tertiary center were enrolled. Diagnosis of ED was performed by using Sexual Health Inventory for Men (SHIM) questionnaire. Patients with a SHIM score ≤21 were defined as having ED. Mean age of patients were 51.8 ± 7.7 and all of the study population were male. Twenty-nine of 50 patients in lone AF group and 25 of 80 patients in control group were diagnosed with ED (58 vs 31.2%, p = 0.002). Mean SHIM score was significantly lower in lone AF group compared with controls (20.74 ± 2.67 vs 22.39 ± 2.21, p < 0.001). The multivariate stepwise logistic regression analyses showed that lone AF (OR 1.94 (1.44-2.46), p < 0.001), smoking (OR 1.92 (1.35-2.44), p = 0.003), fasting blood glucose (OR 1.51 (1.10-1.85), p = 0.012), and uric acid levels (OR 1.56 (1.13-1.92), p = 0.009) were independent predictors of ED. Beat-to-beat variation may lead to ED in patients with paroxysmal lone AF and questioning erectile function in patients with lone AF may be recommended.

LEFT ATRIAL FIBROSIS IN PATIENTS WITH ATRIAL FIBRILLATION ACCORDING TO MAGNETIC RESONANCE IMAGING WITH LATE GADOLINIUM ENHANCEMENT

Актуальность. Фибрилляция предсердий (ФП) – самая распространенная сердечная аритмия. Изучение структуры миокарда предсердий при ФП может послужить основой для создания новых методов лечения аритмии.

Electromechanical delay detected by tissue Doppler echocardiography is associated with the frequency of attacks in patients with lone atrial fibrillation

Our main purpose in this study is to compare atrial (inter-atrial, intra-left atrial, intra-right atrial) electromechanical delays of patients with lone atrial fibrillation (LAF) with healthy individuals and examine the relationship of annual LAF attack frequency. 32 entirely healthy individuals and 32 patients who have presented with tachycardia and complying with LAF criteria have been included in the study. The time passing from the beginning of the P wave on electrocardiography to the A' wave on tissue Doppler trace was accepted as the atrial conduction time (PA'). The PA' time difference between the mitral annulus of left ventricle (ML) and the tricuspid annulus of right ventricle (TL) was defined as inter-atrial electromechanical delay (IA-EMD), the PA' time difference between the ML and septal mitral annulus (MS) as intra-left electromechanical delay (ILeft-EMD), the PA' time difference between MS and the TL as intra-right electromechanical delay (IRight-EMD). ILeft-EMD (21.8 ± 9.1 vs. 14.1 ± 4.9, p < 0.001), IRight-EMD (9.3 ± 6.8 vs. 5.9 ± 4.9, p = 0.03) and IA-EMD times (24.7 ± 11.2 vs. 11.9 ± 7.1, p < 0.001) were significantly longer in LAF patients. In multivariate regression analysis, using a model including age, gender and left atrium (LA) volumes, ILeft-EMD times (OR 1.14, 95% CI 1.03-1.27,p = 0.012), IA-EMD times (OR 1.12, 95% CI 1.03-1.23, p = 0.007) and LA volumes (OR 1.18, 95% CI 1.05-1.32, p = 0.005) were independent predictors of LAF. In LAF group, the frequency of AF episodes was significantly correlated with ILeft-EMD (r = 0.90, p < 0.001) and IA-EMD times (r = 0.36, p < 0.004), whereas, IRight-EMD times and LA volumes were not correlated with recurrence rates. ILeft-EMD and IA-EMD may increase in the early stages of atrial fibrillation even without the left atrial dilation and may be more valuable than left atrial area and volume in predicting atrial fibrillation.

Association between SNP rs13376333 and rs1131820 in the KCNN3 gene and atrial fibrillation in the Chinese Han population.

The small conductance calcium-activated potassium, subfamily N, member 3 (KCNN3) gene rs13376333 and rs1131820 have been shown to be strongly associated with lone atrial fibrillation (AF), while replication association studies between rs13376333 in KCNN3 gene and risk of AF showed conflicting results. The current study tried to validate the impact of SNP rs13376333 and rs1131820 of KCNN3 gene on the risk of AF in the Chinese Han population. A total of 889 AF patients and 1015 controls were enrolled. Two hundred and seventy-eight cases of AF were lone AF. KCNN3 gene SNP rs13376333 and rs1131820 were genotyped by allele-specific MALDI-TOF mass spectrometry. The genotype distribution and allele frequency of rs13376333 polymorphism were not different between total AF patients and controls. However, the genotype distribution of rs13376333 polymorphism was significantly different between lone AF and control group (p<0.001); and T allele frequency was significantly higher in lone AF group than that in controls (7.6% vs 3.6%, p<0.001). Multivariable logistic regression analysis showed that T allele carriers of rs13376333 was significantly associated with lone AF (OR=2.31, 95% CI 1.41-3.78, p=0.001). No relationship between rs1131820 polymorphism and total AF or lone AF was found in this study. KCNN3 rs13376333 polymorphism was associated with lone AF in the Chinese Han population and the T allele carriers may be an independent predictive factor for lone AF.

Assessment of Interleukin‐1 Gene Cluster Polymorphisms in Lone Atrial Fibrillation: New Insight into the Role of Inflammation in Atrial Fibrillation

Systemic inflammation is accepted as one of the pathophysiological mechanisms of atrial fibrillation (AF). The role of inflammation has been shown previously. Interleukin (IL) system is the main modulator of the inflammatory responses and genetic polymorphisms of IL-1 cluster genes are associated with increased risk for inflammatory diseases. To investigate the association between polymorphisms of IL-1 cluster genes and lone AF. DNA samples were collected from 70 proven lone AF patients and 70 healthy subjects. Genomic DNA was typed for the variable number of the tandem repeat (VNTR) IL-1 receptor antagonist (RN) gene polymorphism, IL-1B -511 C > T(rs16944) promoter polymorphism, and +3953 C > T(rs1143634) polymorphism in exon 5 by polymerase chain reaction. In lone AF group the frequency of IL-1RN2/2 and IL-1RN1/2 genotypes were higher than in the control group (7.2% vs 4.3% and 48.5% vs 22.8%, respectively; χ(2) = 14.1; P = 0.028). The frequency of allele 2 was significantly higher in the lone AF group (32.1% vs 15.7%; χ(2) = 10.7; P = 0.005). Allele and genotype distribution of IL-1B -511 C > T and +3953 C > T polymorphisms were not statistically different between the groups. C-reactive protein (CRP) levels were higher in lone AF patients compared to the control group (median = 1.25, interquartile range [IQR] = 0.85 vs median = 1.08, IQR 0.46 mg/L, respectively; P = 0.02). In multivariate regression analysis, presence of allele 2 of IL-1 VNTR polymorphism and elevated plasma high-sensitive-CRP levels were the independent predictors of lone AF. Presence of allele 2 of VNTR polymorphism of IL-1RN gene may cause increased risk for lone AF probably due to the inadequate limitation of inflammatory reactions.

ASSA13-03-1 The Association of SNP Rs3825214 and Atrial Fibrillation in Chinese Han Population

Background Atrial fibrillation (AF) is the most common supraventricular tachycardia encountered in clinical practise associated with pronounced morbidity, mortality, and socio-economic burden. To date, mechanism of AF is still not fully understood but believed to be multifactorial including genetic predisposition. A number of genetic loci and genes related to the disorder have been reported. Recently, several genome-wide association studies (GWAS) have yielded associations between common sequence variants and ECG variables. SNP rs3825214, which is located in the last intron of the TBX5 gene, was shown correlating with the PR interval, the QRS duration, the QT interval and verified significant in diseases as atrial fibrillation, advanced AV block. The postulate that variants on TBX5 influence the occurrence of AF by a new mechanism different from the most extensively accepted ion channel theory may be potential possibility. Objective The aim of this study is to futher assess association between SNP rs3825214 and ECG parametres, AF, ventricular tachycardia (VT), as well as some arrhythmias associating with sudden cardiac death (SCD) in mainland chinese han population. Methods 692 patients as AF group, 235 patients as VT group, and 856 controls in GeneID population were enrolled for case-control association study. Peripheral blood of subjects was extracted through vein. Then cracking red blood cells, separating white blood cells, extracting genomic DNA by SDS alkali cracking method was performed. Genotyping using High Resolution Melt system was performed. The associations of both allele and genotype were analysised by accurate statistical analysis adjusting for potential confounding factors using SPSS 17.0 and PLINK v1.05. Results Subjects form Chinese GeneID population including 692 patients as atrial fibrillation (AF) group, 235 patients as ventricular tachycardia (VT) group, and 856 controls were enrolled in the study. No significant differences were found between the two groups and control subjects with regard to gender, age. we did not find PR interval, QRS duration, QT interval significantly associated with rs3825214. Of note, we observed the association between SNP rs3825214 and QTc (P = 0.047). There was no deviation from the Hardy-Weinberg equilibrium for SNP rs3825214 in control groups (P = 0.8361). Neither male group nor female group was associated with allelic G of SNP rs3825214. A significant association between G allele of SNP rs3825214 and lone atrial fibrillation (LAF) was arresting (P = 0.002; P-adj = 0.001, OR = 0.652). Analysis on other AF, which account for a large percentage in the AF group (60.3%), was shown no significant (P = 0.546). There was also no significant in VT group considering the total VT and other cardiovascular diseases such as bundle branch block, bradycardia, ER, hypertrophic cardiomyopathy, malignant ventricular arrhythmia. However, the assocition of G allele and AF in VT group showed a significant difference (P = 0.004). In both AF and LAF group, the distributions were significantly different compared to the control group with P value equals to 0.029 and 0.003 respectively. No significant interaction was observed between genotypes and ECG measures. Assuming a dominant genetic model, the GG shows strong significant association with AF, and especially LAF. The GG genotype could be a profond protective factor under dominant genetic model as the OR was 0.73 after adjusting for sex, age, T2DM, hypertension, stroke, and CAD. Conclusions The study detected the association of allele G of SNP rs3825214 in TBX5 with QTc and lone AF for the first time. The findings expand the GWAS results to other ethnic population and provide new insight into the molecular aetiology involved in the pathogenesis of lone AF.

SNP RS3825214 IN THE TBX5 GENE IS ASSOCIATED WITH LONE ATRIAL FIBRILLATION IN CHINESE HAN POPULATION

ObjectivesThe prolongation of the PR interval has been considered as an increased risk of atrial fibrillation (AF), pacemaker implantation and mortality. Several recent genome-wide association studies (GWAS) have yielded associations...

Significant Association of rs13376333 in KCNN3 on Chromosome 1q21 With Atrial Fibrillation in a Taiwanese Population

A recent study in individuals of European ancestry demonstrated a significant association of the single nucleotide polymorphism (SNP) rs13376333 in potassium intermediate/small conductance calcium-activated channel, subfamily N, member 3 (KCNN3) on chromosome 1q21 with lone atrial fibrillation (AF), indicating a common genetic basis for AF. The aim of the present study was to investigate whether this association between SNP rs13376333 and AF also exists in Taiwanese subjects. The SNP rs13376333 was compared in 214 lone AF patients (58.3±11.4 years) vs. 214 controls (57.7±13.2 years), and in 322 structural AF patients (69.6±13.7 years) vs. 322 controls (68.4±14.2 years) in a Taiwanese population, in a case-control design. The associations between SNP rs13376333 in KCNN3 and structural or lone AF were significant. In the lone AF group, the frequency of the minor allele of SNP rs13376333 was 8.6% compared with 3.0% in the controls (P<0.001; odds ratio [OR], 3.02; 95% confidence interval [CI]: 1.54-6.29). The frequency of the minor allele of SNP rs13376333 was 6.5% in structural AF patients compared with 3.1% in controls (P=0.004; OR, 2.18; 95%CI: 1.23-3.96). There are significant associations between SNP rs13376333 and the risk of developing both lone and structural AF in the Taiwanese population. The minor allele frequency of SNP rs13376333 was much lower in the Taiwanese population compared to that in the Caucasian population.

Effects of Dronedarone on Clinical Outcomes in Patients with Lone Atrial Fibrillation: Pooled Post Hoc Analysis from the ATHENA/EURIDIS/ADONIS Studies

Dronedarone has been shown to reduce cardiovascular hospitalizations or death in patients with atrial fibrillation (AF) and additional risk factors. This post hoc exploratory analysis examines its effects in the subgroup of lone AF patients. Individual data from patients with lone AF enrolled in the EURIDIS, ADONIS, and ATHENA trials were entered in a central database. The effects of dronedarone compared to placebo on the composite endpoint of cardiovascular hospitalizations or death, and their individual components, were evaluated. A total of 432 (192 placebo and 240 dronedarone) patients (7% of the total population) were classified as having lone AF (69.4% male patients, mean age 64 ± 13 years). The patients were followed for 13.8 ± 7.2 months. The risk for first cardiovascular hospitalizations or death from any cause in the placebo group after 1 year was 25% in the lone AF group compared to 29% the rest of the population. For patients with lone AF, dronedarone led to a 44% reduction of cardiovascular hospitalizations or death (hazard ratio (HR) 0.56; 95%CI 0.36-0.88, P = 0.004) and to a 46% reduction in cardiovascular hospitalizations alone (HR 0.54; 95%CI 0.34-0.87, P = 0.004) compared to placebo. HR for all-cause mortality was 1.02 (95%CI 0.31-3.34, P = 0.885). All findings were homogeneous across the 3 studies and similar to those observed in the overall population. According to this post hoc analysis, patients with lone AF have a high risk for cardiovascular hospitalization within 1 year. Dronedarone when added to standard of care reduces the risk of cardiovascular hospitalizations in this population.

Evaluation of the left atrial substrate in patients with lone atrial fibrillation using delayed-enhanced MRI: implications for disease progression and response to catheter ablation.

Lone atrial fibrillation (AF) is thought to be a benign type or an early stage of the disease. This study sought to compare the left atrium (LA) substrate using delayed-enhanced magnetic resonance imaging (DE-MRI) in patients with lone AF versus those with comorbidities. Forty of 333 included patients met criteria for lone AF. All patients underwent DE-MRI to quantify atrial fibrosis as a marker for structural remodeling (SRM) and underwent catheter ablation. Based on the degree of SRM, patients were staged into 4 groups: Utah I (≤5% LA wall enhancement), Utah II (>5% to ≤20%), Utah III (>20% to ≤35%), or Utah IV (>35%). Distribution in Utah I to IV was comparable in patients with lone AF and non-lone AF. In both groups, a number of patients showed extensive SRM. Mean enhancement (14.08 ± 8.94 vs. 16.94 ± 11.37) was not significantly different between the 2 groups (P = .0721). In the lone AF group, catheter ablation was successful in suppressing AF in all of Utah I, 81.82% of Utah II, 62.5% of Utah III, and none of Utah IV patients. Similar results were achieved in the non-lone AF group. Outcome after ablation was significantly dependent on the SRM of the LA (P < .001). The degree of LA structural remodeling as detected using DE-MRI is independent of AF type and associated comorbidities. Selecting appropriate treatment candidates based on the quality and quantity of atrial fibrosis using DE-MRI would improve procedural outcome and avoid unnecessary intervention.

Increased serum oxidative stress in patients with severe mitral regurgitation: A new finding and potential mechanism for atrial enlargement

Objective The aim of this study was to examine the serum oxidative stress in patients with severe mitral regurgitation. Design and methods This study analyzed serum oxidative stress index in patients with severe mitral regurgitation [persistent atrial fibrillation (AF) or sinus rhythm], paroxysmal lone AF patients and healthy subjects. Results The serum oxidative stress index was significantly higher in the mitral regurgitation AF group and sinus group than in the lone AF group and healthy subjects ( p < 0.0001). Left atrial size was significantly larger in the mitral regurgitation AF group and sinus group than in the lone AF group and healthy subjects ( p < 0.0001). The oxidative stress index significantly and positively correlated with left atrial size in the overall study population ( r = 0.439, p = 0.0008). Conclusions This study provides new evidence of increased oxidative stress in human severe mitral regurgitation, probably contributing to atrial enlargement.

Lone Atrial Fibrillation: Influence of Familial Disease on Gender Predilection

Epidemiological studies report a male predominance in lone atrial fibrillation (LAF). Phenotypic differences between sporadic and familial LAF could aid in deciding which cases should undergo family screening. We sought to determine gender distribution in sporadic and familial LAF, gender-based differences, and phenotypic differences between sporadic and familial LAF. Since November 2000, 192 unrelated LAF probands were recruited. Sporadic LAF was defined as the absence of a family history of LAF. Familial LAF was classified as possible if one first- or second-degree relative had LAF, or confirmed if >or= 2 relatives had LAF. Affected relatives (n = 87) of 34 confirmed familial probands were also evaluated. For unrelated LAF probands, differences in proportions and means were tested using chi(2) and ANOVA, respectively. Difference in gender ratio among the family history groups was tested using mixed models. Male proportion was greater among sporadic (82%) and possible familial probands (84%) than confirmed familial probands (62%), and affected relatives (54%), P < 0.001. Sporadic LAF was more common in men (62%) than women (51%), P = 0.03. More women were affected by palpitation and nocturnal symptoms than men. More patients had permanent AF in the confirmed familial group (27%), compared with the possible familial (7%) and the sporadic LAF group (8%), P = 0.05, but no other phenotypic discriminators were identified. Male predilection for LAF is attenuated as the likelihood of dominant Mendelian inheritance increases. Increased frequency of "sporadic" LAF among men could be partially due to X-linked recessive inheritance. Finally, sporadic and familial LAF are clinically indistinguishable.

Abstract 1738: Lone Atrial Fibrillation: Long-Term Clinical and Echocardiographic Follow-up from the Canadian Registry of Atrial Fibrillation

Background: The natural history of lone atrial fibrillation (AF) is unclear with conflicting data in the literature. We aimed to better describe the clinical outcomes and echocardiographic changes associated with lone AF. Methods: The Canadian Registry of Atrial Fibrillation (CARAF) enrolled 803 non-surgical and non-flutter patients with new onset AF between 1990 and 1996. At enrollment, patients were classified as lone AF (LAF) or not lone AF (Not LAF) based on structural heart disease or hyperthyroidism. Clinical data was prospectively collected with follow-up at 3 months, 1 year, then annually; echocardiograms were performed at enrollment and years 2, 4, and 7. Results: The LAF group (n=212) had a median age of 57 (1 st quartile 44, 3 rd quartile 67) while the Not LAF group (n=591) had a median age of 67 (59, 73), p&lt;0.0001. During the median follow-up of 8 years in the LAF group and 7 years in the Not LAF group, there was a significant difference in survival free from stroke or embolism favoring the LAF group (Figure ). At 8 years, the probability of remaining free of chronic AF was 78.8% vs 69.3% (p=0.02) and free of symptomatic or documented recurrence of AF was 40.1% vs 26.9% (p&lt;0.01) in the LAF vs Not LAF group. The LAF group had smaller LV diastolic and systolic dimensions by 5.5% and 10.2%, respectively, vs the Not LAF group (p&lt;0.0001). The LV mass was smaller at baseline by 21.1% (p&lt;0.0001) vs the Not LAF group, but increased at a greater rate (4.0% vs 0.9%/2 years, p&lt;0.0001). Conclusions: Lone AF, compared to non-lone AF, is associated with a lower rate of death, stroke or embolism, recurrence and progression to chronic AF. Interestingly, LV mass increased significantly only in the Lone AF group.

Familial clustering of lone atrial fibrillation in patients with saddleback-type ST-segment elevation in right precordial leads

We recently identified a large family with a high prevalence of lone atrial fibrillation (AF) and saddleback-type ST-segment elevation in leads V(1-3), without a history of ventricular arrhythmias or syncope. On the basis of this finding, we studied whether there is a relationship between saddleback ST-elevation and lone AF. We examined 168 (mean age 50+/-8 years, 130 males) lone AF patients and 541 (mean age 50+/-6 years, 274 males) healthy subjects. The prevalence of saddleback ST-elevation was higher in the lone AF group than the control group (10 vs. 0.4%, P<0.001). None had a coved-type ST-elevation in baseline ECG or during drug challenge with ajmaline or flecainide (n=13), a family history of sudden cardiac death, ventricular tachyarrhythmias, syncope, or any other features diagnostic to the Brugada syndrome. Familial clustering of lone AF (i.e. AF in >30% of first-degree relatives) was more common among the subjects with saddleback ST-elevation (24 vs. 7%, P=0.03). Saddleback-type ST-segment elevation is a relatively common finding among patients with lone AF. The familial clustering of the disorder indicates that genetic factors may be involved in the pathogenesis of the ECG abnormality and lone AF in these patients.

Effect of atrial pressure increase on effective refractory period and vulnerability to atrial fibrillation in patients with lone atrial fibrillation.

There is evidence suggesting that atrial fibrillation (AF) may be induced by acute increase of atrial pressure. The aim of the present study was to investigate the effect of alterations in atrial pressure, induced by varying the atrioventricular (AV) interval, on atrial refractoriness, and on the frequency of induction of (AF), in patients with a history of lone atrial fibrillation (LAF). Twenty-five patients were included in this study. The patients were divided in two groups: the LAF group, and the control group. None of the patients in either group had organic heart disease. Effective refractory period (ERP) and duration of atrial extrastimulus electrogram (A(2)) were measured at two right atrial sites (high lateral wall, atrial appendage) during AV pacing (cycle length: 500 msec) with different AV intervals. Peak, minimal and mean atrial pressure increased from 8.57 +/- 2.37 to 18.14 +/- 4.74 mm Hg, 2 +/- 2.23 to 5.14 +/- 2.60 mm Hg (p = 0.0001) and from 4.28 +/- 1.6 mm Hg to 9.77 +/- 2.9 mm Hg (p = 0.001), respectively during AV interval modification. During lateral and atrial appendage pacing, with a progressive decrease of AV interval to 160, 100, 80, 40, 0 msec, the ERP, the dispersion of ERP, functional refractory period (FRP), A2 and latency period (LP) did not change significantly, in both groups. The frequency of induction of AF was not statistically different in both lateral atrial wall and appendage, during pacing in different AV intervals. This study demonstrates that alterations in the intraatrial pressure does not have important effects on atrial refractoriness and does not increase vulnerability to AF in patients with a history of LAF.

Characteristics and Prognosis of Lone Atrial Fibrillation

In 30 years of follow-up of 5,209 participants in the Framingham Study, 193 men and 183 women developed atrial fibrillation (AF). Among this group, "lone" AF occurred in 32 men and 11 women free of coronary heart disease, congestive heart failure, rheumatic heart disease, and hypertensive cardiovascular disease. To determine the characteristics and prognosis of lone AF, each case was matched to controls in the remaining Framingham sample. Comparisons indicated that levels of several risk factors associated with coronary heart disease were similar between the two groups. Atrial fibrillation cases, however, had significantly higher rates of preexisting nonspecific T- or ST-wave abnormalities and intraventricular block as determined by electrocardiograms. Follow-up for new cardiovascular events indicated similar rates of coronary heart disease and congestive heart failure, but the rate of strokes was significantly greater in the lone AF group. Findings suggest that subjects with lone AF, despite similar cardiovascular risk profiles to normal controls, have a distinct preponderance of preexisting electrocardiographic abnormalities. Furthermore, contrary to general belief, lone AF is not a benign condition; it has a serious prognosis, indicating a greater need for detection and treatment.