Interatrial Block in the Modern Era

Interatrial block (IAB; P-wave duration ≥ 110 ms), which represents a delay in the conduction between the atria, is a pandemic conduction abnormality that is frequently underappreciated in clinical practice. Despite its comprehensive documentation in the medical literature, it has still not received adequate attention and also not adequately described and discussed in most cardiology textbooks. IAB can be of varying degrees and classified based on the degree of P-duration and its morphology. It can transform into a higher degree block and can also manifest transiently. IAB may be a preceding or causative risk factor for various atrial arrhythmias (esp. atrial fibrillation) and also be associated with various other clinical abnormalities ranging from left atrial dilation and thromboembolism including embolic stroke and mesenteric ischemia. IAB certainly deserves more attention and prospective studies are needed to formulate a standard consensus regarding appropriate management strategies.     

Síndrome de Bayés. Lo que todo clínico debe conocer

Bayés syndrome is a new clinical entity, characterized by the association of advanced interatrial block (IAB) on surface electrocardiogram with atrial fibrillation (AF) and other atrial arrhythmias. This syndrome is associated with an increased risk of stroke, dementia, and mortality. Advanced IAB is diagnosed by the presence of a P-wave ≥ 120 ms with biphasic morphology (±) in inferior leads. The cause of IAB is complete Bachmann bundle blockade, leading to retrograde depolarization of the left atrium from areas near the atrioventricular junction. The anatomic substrate of advanced IAB is fibrotic atrial cardiomyopathy. Dyssynchrony induced by advanced IAB is a trigger and maintenance mechanism of AF. This alteration of the atrial architecture produces atrial remodeling, blood stasis and hypercoagulability, triggering the thrombogenic cascade. The presence of advanced IAB, even in patients without documented atrial arrhythmias, has also been associated with AF, stroke, dementia, and mortality. However, in these patients, there is no evidence to support the use of anticoagulation. Therefore, in patients with advanced IAB, a proactive search for AF is recommended.     

Increased P-wave dispersion predicts recurrent atrial fibrillation after cardioversion

Atrial fibrillation (AF) will recur in a number of patients treated with cardioversion. Being able to identify reliable risk factors would be useful for making management decisions. P-wave dispersion (PWD) is an electrocardiographic measurement, which reflects a disparity in atrial conduction. P-wave dispersion has been shown to be increased in patients with paroxysmal AF. This pilot study aims to determine the role of PWD in predicting AF recurrence in patients who underwent elective cardioversion. Forty-five patients who were successfully cardioverted for persistent AF were included for study. Eighteen patients had a PWD greater than 80 ms; of these 13 had AF recurrence. Of the 25 patients with PWD less than 80 milliseconds, 12 had recurrent AF. P-wave dispersion values greater than 80 milliseconds were found more frequently in patients with AF recurrence (P = .05), supporting the use of this parameter in predicting return of AF. Larger studies are needed for further evaluation.     

Shorter Minimum P-Wave Duration Is Associated with Paroxysmal Lone Atrial Fibrillation

Background and Purpose

Prolonged P-wave dispersion (PWD) and P-wave duration (PWdur) have been found to be associated with common atrial fibrillation (AF), but the association of P-wave indices with lone atrial fibrillation (LAF) is unclear.

Methods

We enrolled 61 paroxysmal LAF cases and 150 controls without AF. P-wave indices were measured from a 12-lead ECG. Multivariable logistic regression was used to assess the association between P-wave indices and LAF.

Results

PWD was longer in LAF patients (median, IQR; 54.1 [42.9–63.2] ms) than controls (46.0 [38.5–57.7] ms), P = 0.03. MinPWdur was shorter in LAF patients (60.5 [50.7–72.6] ms) than controls (66.0 [55.5–76.4] ms), P = 0.03. In multivariable models, only the association between shorter minPWdur and LAF remained statistically significant (OR [95% CI] per tertile increment in minPWdur, 0.64 [0.42–0.95], P = 0.03).

Conclusions

Unlike common AF, paroxysmal LAF is independently associated with shorter minPWdur. This finding suggests that both shorter and prolonged PWdur may be associated with increased risk of AF.     

Resumption of interatrial conduction after atrial premature beat in baseline interatrial aberrancy

Interatrial block (IAB) is a delay or blockage of interatrial conduction from the right atrium to the left atrium, causing prolongation of the P-wave duration on the electrocardiogram. This condition is unfortunately not uncommon in clinical practice, especially among the elderly. It is often overlooked because the P wave is small and abnormalities can be difficult to detect. An isolated IAB does not usually cause any abnormal symptoms and may not require any specific treatment. Nevertheless, a relationship between an IAB and other cardiovascular conditions including left atrial electromechanical dysfunction, atrial remodeling, atrial fibrosis, atrial fibrillation, and stroke has been reported. Early diagnosis of this condition is critical. This case report presents a functional interatrial block or interatrial aberrancy that returned to normal after an atrial premature complex where the interatrial conduction remained normal in subsequent beats.     

老年心血管病患者房颤反复发作的预测

目的　为明确老年心血管疾病患者窦性心律时发生阵发性房颤的危险因素并寻找反复心房颤动发作的预测因子。方法　测量 71例有阵发性房颤发作史的老年心血管疾病患者 (PAF组 )及 73例无阵发性房颤发作史的老年心血管疾病患者 (对照组 )窦性心律时的 12导联ECG ,分别测定最大P波时限 (Pmax)及最小P波时限 (Pmin)并计算其P波离散度 (Pd) ,心脏超声测量左房内径 (LAD)和左室射血分数 (LVEF) ,随访PAF组房颤反复发作情况。结果　PAF组的Pd及Pmax分别为 ( 4 7.0 7± 12 .3 5 )ms和 ( 12 1.2 5± 13 .2 4)ms,较对照组明显延长 (P <0 .0 1) ;PAF组反复房颤发作者 ,Pd≥40ms时相对危险度 3 .3 3 ,Pmax≥ 110ms时相对危险度 2 .48。结论　窦性心律时Pd、Pmax增加是预测老年心血管病患者是否发生房颤及房颤反复发作的有效且无创的临床方法     

Reduction of P-wave duration and successful pulmonary vein isolation in patients with atrial fibrillation

Introduction: We hypothesize that successful pulmonary vein (PV) isolation can shorten the P-wave duration in patients with atrial fibrillation (AF).
Methods and Results: We recorded magnified surface electrocardiogram (ECG) and P-wave signal-averaged ECG using 12 electrode leads before and after 31 PV isolation procedures in 27 patients with AF. The patients were followed for 16 ± 4 months. Repeat ablation studies documented failed PV isolation in seven patients with AF recurrences. At baseline, the maximal P-wave duration in patients without AF recurrence (161 ± 7 msec) was slightly shorter than that in patients with AF recurrence (168 ± 10 msec, P < 0.05). After ablation, patients without recurrence showed a significant reduction of P-wave duration from 161 ± 7 msec to 151 ± 8 msec (P < 0.0001). In contrast, no change of P-wave duration was noted in patients with recurrences. These findings were confirmed with signal averaged ECG of the P-waves. Three-dimensional (3-D) computer simulation using an atrial cell model showed that elimination of the muscle sleeves inside the PV resulted in a shortening of the P-wave duration and change of the terminal portion of the P-wave morphology.
Conclusions: A significant shortening of P-wave duration by P-wave signal-averaged ECG can be used as an indicator for successful PV isolation. These findings suggest that activation of the PV muscle sleeves may be an important component of the terminal portion of the P-wave on surface ECG.     

Electrophysiologic mechanisms of provoked atrial flutter in mitral valve prolapse syndrome

To examine the electrophysiologic determinants of provoked atrial flutter (AF) in patients with mitral valve prolapse (MVP), studies were performed in 4 groups of patients: group 1 (n = 5), patients with MVP and AF; group 2 (n = 6), patients without MVP but with AF; group 3 (n = 6), patients with MVP but without AF; and group 4 (n = 5), patients without MVP and without AF. P-wave duration, intraatrial conduction, interatrial conduction and effective refractory periods for both the high right atrium and the low right atrium were longer in group 2 than in group 1. The effective refractory period of the low right atrium was longer in group 3 than in group 1. The interatrial conduction interval was longer in group 2 than in group 4. Thus, in patients without MVP, atrial conduction delay is the predominant determinant of AF, whereas differences in right atrial refractoriness appear to be most important to the provocation of AF in the patient with MVP. These differences in atrial refractoriness may be a result of abnormal autonomic influences in patients with MVP.     

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.     

Interatrial block: is it time for more attention?

Interatrial block (IAB) is defined as delayed conduction between the right and left atrium, which results in prolonged P-wave duration (≥110 milliseconds). Interatrial block can be partial or advanced (much less common), depending on the severity of the conduction abnormality. Several studies have reported that the prevalence of IAB is more than 40% in hospital inpatients. Despite this, IAB remains largely underdiagnosed and commonly ignored. Although more investigations are needed to identify the cause of IAB, coronary artery disease and conditions related to cardiovascular disease, such as hypertension or diabetes mellitus, have been described as potential risk factors for developing IAB. Interatrial block has strong associations with multiple medical conditions including atrial fibrillation, myocardial ischemia, left atrial enlargement, and systemic emboli. Treatment modalities for IAB to preclude its consequences include pacing and medical management, in which angiotensin-converting enzyme inhibitors and angiotensin receptor blockers have given promising results. However, more interest, attention, and research for IAB is required to explore this uncertain issue thoroughly.     

Comparison of P-wave duration and dispersion in patients aged > or =65 years with those aged < or =45 years

P-wave dispersion (PWD) is a new electrocardiographic marker that reflects discontinuous and inhomogeneous propagation of sinus impulses, which has been studied in some cardiac conditions as a useful predictor of paroxysmal atrial fibrillation (AF). The aim of the peresent study was to compare P-wave duration and PWD in patients < or =45 versus > or =65 years of age. The study consisted of 2 groups. Group I included 118 patients aged > or =65 years (86 men, 32 women, mean age= 69 +/- 4 years). Group II included 72 patients aged < or =45 years (53 men, 19 women, mean age= 41 +/- 4 years). All patients were selected from those who were undertaken coronary angiography in our hospital with a suspicion of coronary artery disease and detected as having angiographically normal coronary arteries. All patients were undertaken transthoracic echocardiography to evaluate the presence of any structural and functional cardiac abnormality. Maximum and minimum P-wave durations and PWD were calculated from 12-lead surface electrocardiogram. Maximum P-wave duration and PWD were significantly higher in group I patients than in group II patients (P <.001). However, there was no statistically significant difference between group I patients and group II patients regarding minimum P-wave duration (p=0.9). Left atrial diameter, left ventricular wall thicknesses, mitral A velocity, deceleration time and isovolumic relaxation time were significantly higher in group I patients than in group II patients. However, mitral E velocity were significantly lower in group I patients than in group II patients. A significant positive correlation was detected between PWD and age, left atrial diameter, mitral A velocity, deceleration time and isovolumic relaxation time. In addition, we found a significant negative correlation between PWD and mitral E velocity. PWD, indicating increased risk for paroxysmal AF, was found to be significantly higher in patients > or =65 years of age than in those < or =45 years of age. Further prospective studies that include larger series and long term follow-up are needed to clarify the clinical utility of PWD as a predictor of increased risk for paroxysmal AF in old patients.     

An evaluation of postoperative P-wave variables after cardiothoracic surgery

Postoperative atrial fibrillation is common after cardiac surgery. Prediction of which patients will develop postoperative atrial fibrillation would be clinically useful. Increased P-wave duration, suggesting atrial conduction delay and measured from preoperative electrocardiograms, predicts postoperative atrial fibrillation. However, postoperative P-wave duration has not been evaluated after cardiac surgery. In this study, we evaluated postoperative P-wave variables (maximum P-wave duration and P-wave dispersion) over 5 days in cardiac surgery patients receiving amiodarone, pacing or no atrial fibrillation prophylaxis. P-wave variables gradually shortened as time passed from surgery. Amiodarone did not shorten P-wave measurements throughout therapy, while pacing shortened P-waves in the immediate postoperative period; however, shortening was not sustained. P-waves did not differ between those who did and did not develop atrial fibrillation with amiodarone or pacing. Our findings suggest that atrial conduction delay resulting from cardiothoracic surgery tends to resolve over time and may not play a critical role in the etiology of postoperative atrial fibrillation.     

Clinical prediction rule for atrial fibrillation after coronary artery bypass grafting

OBJECTIVES: This study was designed to devise and validate a practical prediction rule for atrial fibrillation/atrial flutter (AF) after coronary artery bypass grafting (CABG) using easily available clinical and standard electrocardiographic (ECG) criteria. BACKGROUND: Reported prediction rules for postoperative AF have suffered from inconsistent results and controversy surrounding the added predictive value of a prolonged P-wave duration. METHODS: In 1,851 consecutive patients undergoing CABG with cardiopulmonary bypass, preoperative clinical characteristics and standard 12-lead ECG data were examined. Patients were continuously monitored for the occurrence of sustained postoperative AF while hospitalized. Multiple logistic regression was used to determine significant predictors of AF and to develop a prediction rule that was evaluated through jackknifing. RESULTS: Atrial fibrillation occurred in 508 of 1,553 patients (33%). Multivariate analysis showed that greater age (odds ratio [OR] 1.1 per year [95% confidence intervals (CI) 1.0 to 1.1], p < 0.0001), prior history of AF (OR 3.7 [95% CI 2.3 to 6.0], p < 0.0001), P-wave duration >110 ms (OR 1.3 [95% CI 1.1 to 1.7], p = 0.02), and postoperative low cardiac output (OR 3.0 [95% CI 1.7 to 5.2], p = 0.0001) were independently associated with AF risk. Using the prediction rule we defined three risk categories for AF: <60 points, 61 of 446 (14%); 60 to 79 points, 330 of 908 (36%); and >or=80 points, 117 of 199 (59%). The area under the receiver-operator characteristic curve for the model was 0.69. CONCLUSIONS: These data show that post-CABG AF can be predicted with moderate accuracy using easily available patient characteristics and may prove useful in prognostic and risk stratification of patients after CABG. The presence of intraatrial conduction delay on ECG contributed least to the prediction model.     

Can we predict stroke in atrial fibrillation?

Stroke prevention with appropriate thromboprophylaxis still remains central to the management of atrial fibrillation (AF). Nonetheless, stroke risk in AF is not homogeneous, but despite stroke risk in AF being a continuum, prior stroke risk stratification schema have been used to 'artificially' categorise patients into low, moderate and high risk stroke strata, so that the patients at highest risk can be identified for warfarin therapy. Data from recent large cohort studies show that by being more inclusive, rather than exclusive, of common stroke risk factors in the assessment of the risk for stroke and thromboembolism in AF patients, we can be so much better in assessing stroke risk, and in optimising thromboprophylaxis with the resultant reduction in stroke and mortality. Thus, there has been a recent paradigm shift towards getting better at identifying the 'truly low risk' patients with AF who do not even need antithrombotic therapy, whilst those with one or more stroke risk factors can be treated with oral anticoagulation, whether as well-controlled warfarin or one or the new oral anticoagulant drugs. The new European guidelines on AF have evolved to deemphasise the artificial low/moderate/high risk strata (as they were not very predictive of thromboembolism, anyway) and stressed a risk factor based approach (within the CHA(2) DS(2)-VASc score) given that stroke risk is a continuum. Those categorised as 'low risk' using the CHA(2) DS(2)-VASc score are 'truly low risk' for thromboembolism, and the CHA(2) DS(2)-VASc score performs as good as-and possibly better--than the CHADS(2) score in predicting those at 'high risk'. Indeed, those patients with a CHA(2) DS(2)-VASc score = 0 are 'truly low risk' so that no antithrombotic therapy is preferred, whilst in those with a CHA(2) DS(2)-VASc score of 1 or more, oral anticoagulation is recommended or preferred. Given that guidelines should be applicable for >80% of the time, for >80% of the patients, this stroke risk assessment approach covers the majority of the patients we commonly seen in everyday clinical practice, and considers the common stroke risk factors seen in these patients. The European guidelines also do stress that antithrombotic therapy is necessary in all patients with AF unless they are age <65 years and truly low risk. Indeed, some patients with 'female gender' only as a single risk factor (but still CHA(2) DS(2)-VASc score of 1, due to gender) do not need anticoagulation, especially if they fulfil the criterion of "age <65 and lone AF, and very low risk". In the European and Canadian guidelines, bleeding risk assessment is also emphasised, and the simple validated HAS-BLED score is recommended. A HAS-BLED score of ≥ 3 represents a sufficiently high risk such that caution and/or regular review of a patient is needed. It also makes the clinician think of correctable common bleeding risk factors, and the availability of such a score allows an informed assessment of bleeding risk in AF patients, when antithrombotic therapy is being initiated.     

P-wave dispersion in patients with rheumatic mitral stenosis

It has previously been shown that maximum P-wave duration and P-wave dispersion in 12-lead surface electrocardiogram (ECG) are significantly increased in patients prone to developing atrial fibrillation. Because patients with mitral stenosis (MS) are also susceptible to developing atrial fibrillation, the present study was carried out to determine whether maximum P-wave duration and P-wave dispersion are prolonged in MS patients during normal sinus rhythm. In addition, the correlation between these P-wave variables and the left atrial size, transmitral valve gradient and mitral valve area were determined. Fifty consecutive patients (40 women and 10 men; mean age 35.76±6.59 years) with MS who were in normal sinus rhythm, and a control group of 50 age- and sex-matched healthy persons were studied.A 12-lead ECG was obtained for each subject. All ECGs were scanned through a Cannon scanner at 300 dpi and saved as images in a personal computer. The minimum and maximum P-wave durations, as well as P-wave dispersion, were subsequently calculated. In addition, all patients were evaluated by echocardiography to measure the left atrial size, transmitral valve gradient and mitral valve area by planimetry. The P-wave parameters were compared between the two groups and the correlation between these parameters and the echocardiographic variables were determined in patients with MS. The most important findings included a significant prolongation of maximum P-wave duration in patients with MS compared with controls (P<0.001), and a strong correlation between the maximum P-wave duration and left atrial size (r=0.505, P<0.001), transmitral valve gradient (r=0.371, P=0.01) and a significant negative correlation with mitral valve area (r=-0.379, P=0.007). There was no correlation between the P-wave dispersion and echocardiographic parameters.     

环肺静脉线性消融术对P波时限及离散度的影响

目的 对比环肺静脉线性消融术前、术后P波时限和P波离散度,发现环肺静脉线性消融对以上参数的影响.方法 50例阵发性房颤患者,描记消融术前及术后7天窦性心律下同步12导联心电图,分析比较各导联P波时限及P波离散度,术后定期根据症状及动态心电图随访判断手术成功与否.结果 P波时限:Ⅱ、Ⅲ、aVR、V3、V4、V5导联P波时...     

Differences in the morphology and duration between premature P waves and the preceding sinus complexes in patients with a history of paroxysmal atrial fibrillation

BACKGROUND: Atrial fibrillation (AF) is the most common arrhythmia encountered in clinical practice. Experimental and human mapping studies have demonstrated that perpetuation of AF is due to the presence of multiple reentrant wavelets with various sizes in the right and left atria. HYPOTHESIS: Atrial fibrillation may be induced by atrial ectopic beats originating in the pulmonary veins, and premature P-wave (PPW) patterns may help to identify the source of firing. METHODS: To evaluate the morphology and duration of PPWs, 12-lead digital electrocardiogram (ECG) strips containing clearly definable PPWs not merging with the preceding T waves were obtained in 25 patients with AF history (9 men, mean age 59.5 +/- 2.2 years) and 25 subjects without any previous AF history (11 men, mean age 53.6 +/- 25 years). The polarity of PPWs was evaluated in all 12 ECG leads. Previously described indices, such as P maximum, P dispersion (= P maximum-P minimum), P mean, and P standard deviation were also calculated. RESULTS: Premature P-wave patterns were characterized by more positive P waves in lead V1. All P-wave analysis indices were significantly higher in patients with AF than in controls when calculated in the sinus beat, whereas they did not differ between the two groups when calculated in the PPW. P-wave indices did not differ between the PPW and the sinus either patients with AF or controls, except for P mean, which was significantly higher in the sinus (110.1 +/- 1.7 ms) than in the PPW (100 +/- 2 ms) only in patients with AF (p = 0.001). CONCLUSION: The evaluation of PPW patterns is only feasible in a small percentage of short-lasting digital 12-lead ECG recordings containing ectopic atrial beats. Premature P wave patterns characterized by more positive P waves in lead V1, which indicates a left atrial origin in the ectopic foci. The observed differences in P-wave analysis indices between patients with AF and controls and between sinus beats and PPWs may be attributed to the presence of electrophysiologic changes in the atrial substrate.     

低强度华法林抗凝治疗高出血风险房颤患者的有效性及安全性临床研究

目的：应用2010年欧洲心脏病学协会（ESC）房颤新指南提出的新的评分系统卒中危险评分（CHA2DS2-VASc）和首次推出的出血风险评分法（HAS-BLED）,观察CHA2DS2-VASc积分≥1分且HAS-BLED出血风险积分≥3分时,低强度华法林抗凝治疗高出血风险房颤患者的抗栓疗效和安全性。方法2011年1月至2012年1月我院非瓣膜性房颤患者99例,其CHA2DS2-VASc卒中危险评分≥1分且HAS-BLED出血风险积分≥3分。全部病例分成两组,标准强度华法林治疗组[2.0＜国际标准化比值（INR）≤3.0]和低强度华法林治疗组（1.6≤INR≤2.0）。观察两组患者的血栓栓塞率及出血发生率。结果卡方检验结果显示,两组患者的血栓栓塞率差异无统计学意义（P＞0.05）;标准强度华法林治疗组的出血发生率高于低强度华法林治疗组患者,差异有统计学意义（P＜0.05）。结论 CHA2DS2-VASc卒中危险评分≥1分且HAS-BLED出血风险积分≥3分的高出血风险的房颤患者可以采用低强度华法林抗凝,能有效减少血栓栓塞事件的发生,同时不增加严重出血事件,使用安全可靠。     

Acute alcohol intake and P-wave dispersion in healthy men.

OBJECTIVE: P-wave dispersion (Pd), defined as the difference between the maximum and the minimum P-wave duration (Pmin), and maximum P-wave duration (Pmax) are electrocardiographic (ECG) markers that have been used to evaluate the discontinuous propagation of sinus impulses and the prolongation of atrial conduction time, respectively. The incidence of cardiac arrhythmias, particularly atrial fibrillation (AF), following acute alcohol intake has been previously reported. Prolonged P-wave duration and Pd have been reported to represent an increased risk for AF. However, the association between Pd and acute alcohol intake has not been studied previously in normal subjects. METHODS: In a randomized crossover study, 10 healthy male volunteers, aged 30.0+/-2.1 years (range 25-33 years) received either ethanol and/or placebo (juice). Alcohol group drank moderate dose ethanol; 0.97+/-0.12 g/kg body weight (range 0.80-1.25 g/kg), and the other group consumed same amount of juice in one-hour period. After 48-hours washout period, alcohol group took juice and juice group drank alcohol. Pmax, Pmin and Pd were measured as milliseconds (ms) on baseline ECG, after alcohol period (AP) and after juice period (JP). RESULTS: In comparison with baseline, Pmax values were significantly prolonged after AP but not after JP (baseline: 95.3+/-5.3 ms, after AP: 103.7+/-9.5 ms, after JP: 94+/-7 ms, p=0.027, p=0.102, respectively). Pmin values did not change significantly. And also, in comparison with baseline, Pd values were significantly prolonged after AP but not after JP (baseline: 27.0+/-7.6 ms, after AP: 42.7+/-12.8 ms, after JP: 27.0+/-6.7 ms, p=0.021, p=0.891, respectively). CONCLUSION: Acute moderate dose of alcohol intake in short time is associated with an increase in Pmax and Pd.     

Reliable identification of ’truly low’ thromboembolic risk in patients initially diagnosed with ’lone’ atrial fibrillation:The Belgrade atrial fibrillation study

Background The CHA 2 DS 2-VASc schema has recently been introduced to complement the CHADS2 score and improve the identification of atrial fibrillation (AF) patients at ’truly low risk’ for thromboembolism.We tested the predictive ability of the CHA 2 DS 2-VASc,CHADS2 and van Walraven risk stratification schemes in a cohort of ’lone’ AF patients with a 12-year follow-up.Methods and Results We conducted a registry-based,observational cohort study of 345 patients initially diagnosed with ’lone’ AF between 1992 and 2007.At baseline,all patients had the CHADS2 and van Walraven scores of 0,and 262 (75.9%) had a CHA 2 DS 2VASc score=0.During follow-up (or within a year prior to stroke),228 (66.1%),234 (67.8%) and 150 patients (43.5%) retained the CHADS2,van Walraven and CHA 2 DS 2VASc scores of 0,respectively.The overall rate of ischemic stroke was 0.19 (95%CI:0.18-0.20) per 100 patient-years.In the multivariable analysis,only the CHA 2 DS 2-VASc score of 0 was significantly related to the absence of stroke (OR 5.1,95%CI:1.5-16.8,P=0.008).Only the CHA 2 DS 2-VASc score had a significant prediction ability (c-statistic 0.72 [0.61-0.84],P=0.031).Conclusions The CHA 2 DS 2-VASc score reliably identified the ’lone’ AF patients who were at ’truly low risk’ for thromboembolism,and was the only tested risk stratification scheme with a significant predictive ability for thromboembolism amongst lone AF patients.