Anatomical and Electrophysiological Characteristics of Dual-Loop Re-Entry in Atypical Atrial Flutter: Implications for Mapping and Catheter Ablation.

Background: Atypical atrial flutter (AFL) can be challenging to ablate, especially when involving dual-loop re-entry. We sought to assess the electroanatomical characteristics of single- and dual-loop AFLs in patients undergoing catheter ablation. Methods: We analyzed 25 non-cavotricuspid isthmus-dependent macro-re-entrant AFL in 19 consecutive patients. Three-dimensional high-density activation mapping was performed, and active re-entry loops were confirmed by entrainment mapping. Results: Of 25 AFLs (24 left, 1 right atrial), 13 (52%) exhibited dual-loop re-entry. The most common circuits included, in 6/13 (46% of dual loops), a perimitral re-entry with a second loop around the right/left pulmonary veins (PV) and, in 6/13 (46%), involved a right PV ostium with a second loop around either a functional conduction block or another PV. Ablation at the common isthmus of dual-loop AFLs and at the critical isthmus of single-loop AFLs terminated the arrhythmia more frequently than ablation at a secondary isthmus of dual-loop AFLs (5/6 (83%) and 8/11 (73%) versus 1/8 (13%), respectively, p = 0.013). Conclusions: More than half of AFLs exhibited a dual-loop re-entrant mechanism. Most critical isthmuses were found at the mitral isthmus, the left atrial roof or right PV ostia. Ablation targeting the common isthmus resulted in a higher termination rate.

ATE Score Diagnostic Accuracy for Predicting the Absence of Intra-Atrial Thrombi Before AF Ablation.

BACKGROUND: In a preliminary study in patients hospitalized for catheter ablation of atrial fibrillation (AF), the atrial thrombus exclusion (ATE) score (stroke, hypertension, heart failure, and D-dimers >270 ng/mL) was developed to rule out the diagnosis of intra-atrial thrombus, with a negative predictive value (NPV) of 100%, and to avoid performing transesophageal echocardiography (TEE). OBJECTIVES: The present study was designed to prospectively confirm the NPV of the ATE score in an independent population. METHODS: Consecutive patients hospitalized for catheter ablation of AF or left atrial tachycardia (LAT) were prospectively enrolled in a multicenter study. D-dimer levels were measured within 48 hours before ablation. An ATE score of 0 was considered predictive of no thrombus. TEE was routinely performed at the beginning or just before the ablation procedure. The primary endpoint was the presence of atrial thrombus diagnosed by TEE. RESULTS: The analysis included 3,072 patients (53.3% paroxysmal AF, 36.7% persistent AF, and 10% LAT). A thrombus was detected in 29 patients (0.94%; 95% CI: 0.63%-1.35%), all on appropriate anticoagulant therapy. An ATE score of 0 was observed in 818 patients (26.6%), and the sensitivity, specificity, positive predictive value, and NPV were 93.1%, 26.8%, 1.2%, and 99.8%, respectively. Follow-up of the 2 false negative patients revealed the persistence of chronic organized thrombi. CONCLUSIONS: In patients hospitalized for catheter ablation of AF or LAT, the ATE score identifies a population at very low risk for atrial thrombus. In consultation with the patient, the cardiologist may consider not performing a preoperative TEE in case of an ATE score of 0.

Safety, Efficacy and Prognostic Benefit of Atrial Fibrillation Ablation in Heart Failure with Preserved Ejection Fraction.

Up to 65% of patients with heart failure with preserved ejection fraction (HFpEF) develop AF during the course of the disease. This occurrence is associated with adverse outcomes, including pump failure death. Because AF and HFpEF are mutually reinforcing risk factors, sinus rhythm restoration may represent a disease-modifying intervention. While catheter ablation exhibits acceptable safety and efficacy profiles, no randomised trials have compared AF ablation with medical management in HFpEF. However, catheter ablation has been reported to result in lower natriuretic peptides, lower filling pressures, greater peak cardiac output and improved functional capacity in HFpEF. There is growing evidence that catheter ablation may reduce HFpEF severity, hospitalisation and mortality compared to medical management. Based on indirect evidence, early catheter ablation and minimally extensive atrial injury should be favoured. Hence, individualised ablation strategies stratified by stepwise substrate inducibility provide a logical basis for catheter-based rhythm control in this heterogenous population. Randomised trials are needed for definitive evidence-based guidelines.

[Electrocardiographic abnormalities in the setting of acute central nervous system pathology]. / Anomalies de l'ECG secondaires à une lésion du système nerveux central.

Up to 90% of patients with acute central nervous system lesions, such as stroke, exhibit secondary ECG abnormalities, including ST elevation/depression, T wave inversion, prominent U wave, prolonged QTc interval, sinus bradycardia/pause and atrioventricular block. The pathophysiology involves autonomic nervous system disturbance resulting in altered ventricular repolarization gradients, or even myocardial lesions. Clinical assessment aims at distinguishing asymptomatic neurogenic ECG abnormalities from organic heart conditions such as Takotsubo syndrome, myocardial infarction and chronic coronary syndromes. Serial ECG, cardiac biomarkers and echocardiography should be performed, followed by targeted work-up in selected patients. Prolonged QT, arrhythmias or hemodynamic compromise require continuous monitoring and standard management.

Jusqu'à 90 % des patients souffrant de lésions neurologiques aiguës telles que l'AVC présentent des anomalies ECG neurogènes incluant : sus ou sous-décalage ST, onde T inversée, onde U proéminente, prolongement du QTc, bradycardie/pause sinusale et bloc atrioventriculaire. Leur cause semble être une dérégulation neurovégétative provoquant des gradients de repolarisation ventriculaire, voire des lésions myocardiques. Le bilan doit différencier les nombreux patients avec ECG neurogène asymptomatique de ceux présentant une cardiopathie telle qu'un syndrome de Takotsubo, un infarctus ou une maladie coronarienne stable. Le bilan inclut ECG sérié, biomarqueurs cardiaques et échocardiographie, suivis d'un bilan ciblé chez des patients sélectionnés. Un QT long, des arythmies ou une instabilité hémodynamique imposent un monitoring et les mesures habituelles.

Changes in LA volume and diameter correlate with mechanisms of recurrence after paroxysmal AF ablation.

Papathanasiou et al point out that the two different methods of LA volume and diameter measurement in our recent publication could limit the significance of the correlations we reported with PV reconnection and non-PV foci as mechanisms of post AF ablation recurrence. While we acknowledge the lack of statistically significant correlations of smaller echo derived LA diameter with PV reconnection or of a larger angiographic LA volume with non-PV foci, the congruent confidence intervals of this correlation suggest a statistical trend. Non-uniform LA dimensional changes as an expression of structural remodelling may also be a possible explanation. Published data indicates that angiographic LA volumes consistently exhibit a positive bias compared to echocardiographic volumes but do provide intra-procedural measurements better correlating with gold standard techniques like CT or MRI. Finally we agree with Papathanasiou et al that dynamic changes in LA dimensions likely correlate with early and late mechanisms of recurrence and merit prospective studies.

The significance of pulmonary veins isolation radiofrequency time and the evolution of left atrium volume on a twelve-year observational follow-up of paroxysmal atrial fibrillation patients.

AIMS: Pulmonary vein isolation (PVI) is the treatment of choice of paroxysmal atrial fibrillation (PAF). However, radiofrequency delivery at extra-PV sites may be additionally required. We compared clinical and procedural characteristics of patients undergoing PVI alone versus adjunctive extra-PV substrate modification, at first procedure and repeat procedures for AF recurrence. METHODS: 587 patients with PAF undergoing radiofrequency (RF) ablation were retrospectively included. Extra-PV ablation was performed in case of sustained AF despite PVI, or at re-do procedures without PV conduction recovery. Demographic, clinical and electrophysiological predictors of survival without re-intervention were analysed in patients' groups having undergone one (G1), two (G2) or three or more procedures (G3). RESULTS: At baseline procedure, PV RF ablation time was shorter in G1 compared to G2/G3 whereas extra-PV RF ablation time was greater in G3 compared to G1. The proportion of patients requiring PV re-isolation decreased with repeat procedures. Smaller LA before procedure 1 (p1) or p2 was associated with PV reconnection at p2. Conversely larger LA before p1 was associated with extra-PV substrate modification at p2. Late re-do procedure timing (>1yr) was associated with increasing LA volume. Only longer PV and total RF time predicted poorer survival free from AF without re-intervention. CONCLUSION: Longer PV RF time predicted requirement for re-ablation during follow-up. Smaller LA size predicted an increased probability of PV reconnection and decreased extra-PV substrate modification at p2. LA size decreased in patients undergoing early re-intervention, whereas it increased in patients undergoing re-intervention later on suggesting ongoing remodelling or progression.

Recognition of pre-hypertrophic cardiac involvement in Fabry Disease based on automated electrocardiographic measures.

BACKGROUND: Various electrocardiographic (ECG) indices have been shown to be useful for early recognition and staging of cardiac involvement in Fabry Disease (FD). However, many of them lack acceptable sensitivity and specificity. We assessed the value of automated ECG measures to discriminate between pre-hypertrophic FD and healthy individuals. METHODS AND RESULTS: Normal ECGs from 1496 healthy individuals (57.4% male, age 37.4 ± 13 years) were compared to those of 142 FD patients without LVH (37.3% male, age 41.5 ± 18 years). All ECGs were analyzed centrally and a total of 429 automated ECG measures per individual were included for step-wise analysis. The Cramer V statistic was first used to pick out those parameters which were helpful in discriminating between the two groups and a final selection was made by using two models, namely the FLD (Fisher Linear Discrimination) and the Logistic model, to optimise diagnostic performance for the detection of cardiac involvement in FD patients vs. specificity in healthy individuals. The three-step statistical analysis identified 9 ECG parameters as most significant for the discrimination between the groups. The combined discriminant score yielded 64% sensitivity and 97% specificity for correct classification of FD patients in the test sample with a logistic area under curve of the ROC analysis of 0.97. CONCLUSION: The combination of automated ECG measures identified via a stepwise statistical approach may be useful for detection of FD patients in the pre-hypertrophic stage. These data are promising for screening purposes in the very early stages of FD cardiomyopathy and warrant prospective confirmation.

The myocardial phenotype of Fabry disease pre-hypertrophy and pre-detectable storage.

AIMS: Cardiac involvement in Fabry disease (FD) occurs prior to left ventricular hypertrophy (LVH) and is characterized by low myocardial native T1 with sphingolipid storage reflected by cardiovascular magnetic resonance (CMR) and electrocardiogram (ECG) changes. We hypothesize that a pre-storage myocardial phenotype might occur even earlier, prior to T1 lowering. METHODS AND RESULTS: FD patients and age-, sex-, and heart rate-matched healthy controls underwent same-day ECG with advanced analysis and multiparametric CMR [cines, global longitudinal strain (GLS), T1 and T2 mapping, stress perfusion (myocardial blood flow, MBF), and late gadolinium enhancement (LGE)]. One hundred and fourteen Fabry patients (46 ± 13 years, 61% female) and 76 controls (49 ± 15 years, 50% female) were included. In pre-LVH FD (n = 72, 63%), a low T1 (n = 32/72, 44%) was associated with a constellation of ECG and functional abnormalities compared to normal T1 FD patients and controls. However, pre-LVH FD with normal T1 (n = 40/72, 56%) also had abnormalities compared to controls: reduced GLS (-18 ± 2 vs. -20 ± 2%, P < 0.001), microvascular changes (lower MBF 2.5 ± 0.7 vs. 3.0 ± 0.8 mL/g/min, P = 0.028), subtle T2 elevation (50 ± 4 vs. 48 ± 2 ms, P = 0.027), and limited LGE (%LGE 0.3 ± 1.1 vs. 0%, P = 0.004). ECG abnormalities included shorter P-wave duration (88 ± 12 vs. 94 ± 15 ms, P = 0.010) and T-wave peak time (Tonset - Tpeak; 104 ± 28 vs. 115 ± 20 ms, P = 0.015), resulting in a more symmetric T wave with lower T-wave time ratio (Tonset - Tpeak)/(Tpeak - Tend) (1.5 ± 0.4 vs. 1.8 ± 0.4, P < 0.001) compared to controls. CONCLUSION: FD has a measurable myocardial phenotype pre-LVH and pre-detectable myocyte storage with microvascular dysfunction, subtly impaired GLS and altered atrial depolarization and ventricular repolarization intervals.

Significance of post-pacing intervals shorter than tachycardia cycle length for successful catheter ablation of atypical flutter.

AIMS: During entrainment mapping of macro-reentrant tachycardias, the time difference (dPPI) between post-pacing interval (PPI) and tachycardia cycle length (TCL) is thought to be a function of the distance of the pacing site to the re-entry circuit and dPPI < 30 ms is considered within the re-entry circuit. This study assessed the importance of PPI < TCL as a successful target for atypical flutter ablation. METHODS AND RESULTS: A total of 177 ablation procedures were investigated. Surface electrocardiograms (ECGs) were evaluated and combined activation and entrainment mapping were performed to choose ablation sites. Each entrainment sequence immediately preceding static radiofrequency delivery at the same site was analysed. A total of 545 entrainment sequences were analysed. dPPI < 0 ms was observed in 45.3% (247/545) sequences. Ablation resulted in tachycardia termination more often at sites with dPPI < 0 (27.8% vs. 14.5%, P < 0.001) and with a progressively increasingly inverse correlation between dPPI duration and ablation success [odds ratio (OR): 0.974; 95% confidence interval (CI) 0.960-0.988; P < 0.001]. Tachycardia termination or cycle length prolongation also occurred more often at sites with dPPI < 0 (50.6% vs. 33.2%, P < 0.001) and with a similar inverse correlation with dPPI duration (OR: 0.972; 95% CI 0.960-0.984; P < 0.001). Twelve-lead synchronous isoelectric intervals were observed in 64.4% (163/253) flutter ECGs and were associated with a dPPI < 0 (75.3% vs. 55.8%, P < 0.001). CONCLUSION: When combined with activation mapping, a negative dPPI is a more effective parameter for identifying a target for successful ablation compared to a dPPI = 0-30 ms. Its occurrence is associated with a critical small narrow slow-conducting isthmus at the target site.

Right Atrial Complexity Evolves With Stepwise Left-Sided Persistent Atrial Fibrillation Substrate Ablation and Predicts Outcomes.

OBJECTIVES: This study sought to study the relation between outcomes of modified stepwise atrial fibrillation (AF) substrate ablation and dynamic electrogram characteristics in the coronary sinus (CS) and right atrium (RA). BACKGROUND: Identifying patients with persistent AF who will benefit from limited lesion sets versus those requiring extensive substrate modification is challenging. METHODS: We studied 70 patients undergoing persistent AF ablation, 43 with acute success (successful ablation [sABL], AF termination, or noninducibility) and 27 with failure (failed ablation [fABL], no termination, or induced AF of >5 minutes). Dominant frequency (DF) and sample entropy (SampEn, increasing with signal complexity) were measured on 30-second recordings of wide-coverage simultaneous RA and CS electrograms during baseline AF and induced AF post-pulmonary vein isolation and after left-sided electrogram-guided ablation steps (on the CS with or without the left atrium [LA]). RESULTS: At baseline AF, patients with sABL exhibited lower RA SampEn (p = 0.023) and lower CS DF (p = 0.030) compared to fABL. A positive RA-to-CS SampEn gradient predicted ablation failure (48% vs. 19% for patients in fABL vs. sABL; p = 0.015). A positive RA-to-CS DF gradient developed in patients with fABL after extra-pulmonary vein substrate modification, unlike patients with sABL (p = 0.0008). At 24 months, 76% of patients were AF free, and 68% were arrhythmia free. sABL was associated with fewer AF recurrences (hazard ratio: 0.31; 95% confidence interval: 0.12-0.84; p = 0.021). A negative RA-to-CS SampEn gradient at baseline was associated with freedom from AF (-0.14 ± 0.19 vs. 0.04 ± 0.18; p = 0.002). CONCLUSIONS: RA greater than CS electrogram complexity gradients at baseline or developing during ablation are associated with unfavorable acute and long-term outcomes of persistent AF ablation. These parameters allow monitoring of the effects of left-sided substrate ablation and, therefore, a rational choice of additional RA substrate modification.

Sustained and self-terminating atrial fibrillation induced immediately after pulmonary vein isolation exhibit differences in coronary sinus electrical activity from onset.

INTRODUCTION: Little data exists on the electrophysiological differences between sustained atrial fibrillation (sAF; >5 minutes) vs self-terminating nonsustained AF (nsAF; <5 minutes). We sought to investigate the electrophysiological characteristics of coronary sinus (CS) activity during postpulmonary vein isolation (PVI) sAF vs nsAF. METHODS AND RESULTS: We studied 142 patients post-PVI for paroxysmal AF (PAF). In a 50-patient subset, CS electrograms in the first 30 seconds of induced AF were analyzed manually. A custom-made algorithm for automated electrogram annotation was derived for validation on the whole patient set. In patients with sAF post-PVI, CS fractionated potentials were ablated. Manual analysis showed that patients with sAF exhibited higher activation pattern variability (2.1 vs 0.5 changes/sec; P < .001); fewer proximal-to-distal wavefronts (25 vs 61%; P < .001); fewer unidirectional wavefronts (60 vs 86%; P < .001); more pivot locations (4.3 vs 2.1; P < .001); shorter cycle lengths (190 vs 220 ms; P < .001); and shorter cumulative isoelectric segments (35 vs 44%; P = .045) compared to nsAF. These observations were confirmed on the whole study population by automated electrogram annotation and sample entropy computation (SampEn: 0.29 ± 0.15 in sAF vs 0.15 ± 0.05 in nsAF; P < .0001). The derived model predicted sAF with 78% sensitivity, 88% specificity; agreement with manual model: 88% (Cohen's kappa= 0.76). CS defragmentation resulted in AF termination or noninducibility in 49% of sAF. CONCLUSION: In PAF patients post-PVI, induced sAF shows greater activation sequence variability, shorter cycle length, and higher SampEn in the CS compared to nsAF. Automated electrogram annotation confirmed these results and accurately distinguished self-terminating nsAF episodes from sAF based on 30-second recordings at AF onset.

Individualised Approaches for Catheter Ablation of AF: Patient Selection and Procedural Endpoints.

Pulmonary vein isolation (PVI) is the cornerstone of AF ablation, but studies have reported improved efficacy with high rates of repeat procedures. Because of the large interindividual variability in the underlying electrical and anatomical substrate, achieving optimal outcomes requires an individualised approach. This includes optimal candidate selection as well as defined ablation strategies with objective procedure endpoints beyond PVI. Candidate selection is traditionally based on coarse and sometimes arbitrary clinical stratification such as AF type, but finer predictors of treatment efficacy including biomarkers, advanced imaging and electrocardiographic parameters have shown promise. Numerous ancillary ablation strategies beyond PVI have been investigated, but the absence of a clear mechanistic and evidence-based endpoint, unlike in other arrhythmias, has remained a universal limitation. Potential endpoints include functional ones such as AF termination or non-inducibility and substrate-based endpoints such as isolation of low-voltage areas. This review summarises the relevant literature and proposes guidance for clinical practice and future research.

Electrophysiological and Anatomical Correlates of Sites With Postpacing Intervals Shorter Than Tachycardia Cycle Length in Atypical Atrial Flutter.

Background Although entrainment mapping is an established approach to atypical atrial flutter ablation, postpacing intervals shorter than tachycardia cycle length (difference between postpacing interval and tachycardia cycle length [dPPI] <0 ms) remain of unknown significance. We sought to compare anatomic and electrophysiological properties of sites with dPPI <0, dPPI=0-30, and dPPI >30 ms. Methods We studied 24 noncavotricuspid isthmus-dependent macroreentrant atypical atrial flutter in 19 consecutive patients. Ultra high-density electroanatomic activation maps were acquired with a 64-electrode basket catheter. Entrainment mapping was performed at multiple candidate sites. Ablation was performed at the narrowest accessible slow-conducting critical isthmuses. Results Of 102 entrainment mapping sites, dPPI <30 was observed at 72 sites on complete maps of 24 atypical atrial flutter. Compared with dPPI=0-30 sites (N=45), dPPI<0 sites (N=27) were more commonly located within isthmuses <15 mm wide (67% versus 6.7%, P<0.00001; odds ratio, 28.0; 95% CI, 6.8-115.7), more frequently located within 5 mm of the leading wavefront (93% versus 64%, P=0.008), exhibited slower local conduction velocity (0.49±0.43 versus 0.93±0.57 m/s, P=0.0005), lower voltages (0.48±0.79 versus 0.92±0.97 mV, P=0.04), and more frequently fractionated electrograms (67% versus 24%, P=0.0004). High rates of arrhythmia termination or cycle length increase >15 ms by ablation were observed in both dPPI groups (94% versus 86%, P=0.53). Compared with all dPPI <30, dPPI >30 sites (N=30) were less commonly observed within isthmuses (3.3%, P<0.001) or within 5 mm of the leading wavefront (30%, P<0.0001); conduction velocity (1.0±0.7 m/s, P=0.002) and voltage (1.1±1.4 mV, P=0.049) were higher compared with dPPI<0 but similar to dPPI=0-30 sites. Conclusions In atypical atrial flutter, sites with dPPI <0 are markers of limited width critical isthmuses with slower conduction velocity, whereas sites with dPPI=0-30 ms are often not in close proximity to the reentry circuit. Virtual electrode simultaneous down and upstream (antidromic) capture of a confined isthmus of slow conduction can explain a dPPI <0. Identifying these sites may improve selective and efficient ablation strategies compared with the standard 30-ms threshold.

Evolution of post-pulmonary vein isolation atrial fibrillation inducibility at redo ablation: Electrophysiological evidence of extra-pulmonary vein substrate progression.

BACKGROUND: The electrophysiological substrate underlying atrial fibrillation (AF) progression remains difficult to identify. OBJECTIVE: The goals of this study were to study the evolution of post-pulmonary vein isolation (PVI) AF inducibility (AFI) after AF ablation and to compare patients with organized atrial tachycardia recurrence (OATr) versus those with paroxysmal or persistent AF recurrence. METHODS: We studied 99 patients who underwent de novo AF ablation (p1) and redo ablation (p2) for AF recurrence (AFr) or OATr. Stepwise AF ablation was performed at p1 and p2: (1) PVI, (2) coronary sinus defragmentation, and (3) left atrial (LA) defragmentation. Burst pacing followed each step, with AFI defined as sustained AF >5 minutes, triggering the next step. Patients with OATr underwent OAT ablation and inducibility testing post-redo PVI. Inducibility progression (IP) was defined as AFI at further steps of p2 compared to p1. RESULTS: Among patients with AFr, 34 of 72 patients (47%) exhibited post-PVI IP vs 2 of 27 (7.4%) patients with OATr (P = .0002). Stratification for persistent AF/paroxysmal AF/OATr showed a consistent association between recurrence phenotype and IP. Pulmonary vein (PV) reconnection incidence was 90%, without association with recurrence type or IP. LA volume was larger in patients with IP than in those without IP (86.7 ± 25.3 mL vs 72.0 ± 28.9 mL; P = .001). Right atrial dimensions increased between p1 and p2 in patients with IP vs no IP and in patients with AFr vs OATr. CONCLUSION: Patients with AFr after first ablation exhibit IP more frequently at redo ablation than do patients with OATr. IP correlates with more advanced AFr type, larger LA volumes, and progressive right atrial enlargement. PV reconnection is not associated with AFr. Changes in post-PVI AFI may accurately indicate progression of extra-PV AF-maintaining substrate.

Intra- and interatrial conduction abnormalities: hemodynamic and arrhythmic significance.

Alterations of normal intra- and interatrial conduction are a common outcome of multiple cardiovascular conditions. They arise most commonly in the context of advanced age, cardiovascular risk factors, organic heart disease, atrial fibrosis, and left atrial enlargement. Interatrial block (IAB), the most frequent and extensively studied atrial conduction disorder, affects up to 20% of the general primary care population. IAB can be partial (P wave duration ≥ 120 ms on any of the 12 ECG leads) or advanced (P wave ≥ 120 ms and biphasic morphology (positive-negative) in inferior leads). Advanced IAB is an independent risk factor for supraventricular tachyarrhythmias and embolic stroke in a variety of clinical settings. Advanced IAB is a cause of left atrial electromechanical dysfunction and left atrioventricular dyssynchrony and has been associated with left ventricular diastolic dysfunction. P wave duration is associated with cardiovascular and all-cause mortality in the general population. Atrial conduction abnormalities should be identified as markers of atrial remodeling, prognostic indicators, and, in the case of advanced IAB, a true arrhythmologic syndrome. IAB and other P wave abnormalities should prompt the search for associated conditions, the treatment of which may partially reverse atrial remodeling or prevent it if administered upstream. Future studies will help define the role of preventive therapeutic interventions in high-risk patients, including antiarrhythmic drug therapy and oral anticoagulation. Implications for the treatment of heart failure and for pacing should also be further investigated.

[ECG : interpretation and clinical significance of P-wave abnormalities]. / ECG : interprétation et signification clinique des anomalies de l'onde P.

The ECG provides information about heart rhythm and myocardial integrity, including the atria. The sinus P wave exhibits a 0­90° axis and a generally biphasic morphology in lead V1. An amplitude >2 mm in lead II and >1 mm in lead V1 is a specific sign of right atrial enlargement, often related to pulmonary disease or pulmonary hypertension. Interatrial block (IAB) is defined as a P-wave ≥120 ms with, in the advanced form, a biphasic morphology in inferior leads. It is most commonly seen in the context of advanced age, cardiovascular risk factors, coronary artery disease or valvulopathies. IAB is a risk factor for supraventricular tachyarrhythmias, stroke, left ventricular dysfunction and mortality. The identification of a P-wave abnormality has prognostic implications and should trigger the search for associated conditions.

L'ECG (électrocardiogramme) renseigne sur le rythme et l'intégrité du myocarde, y compris atrial. L'onde P sinusale présente un axe de 0­90° et une morphologie généralement biphasique en V1. Une amplitude > 2 mm en II et > 1 mm en V1 est un signe spécifique de dilatation de l'oreillette droite, marqueur de pneumopathie ou d'hypertension pulmonaire. Le bloc interatrial (BIA) est défini par une onde P ≥ 120 ms avec, dans la forme avancée, une morphologie biphasique en dérivations inférieures. Il est souvent observé dans un contexte d'âge avancé, de facteurs de risque cardiovasculaire, de maladie coronarienne ou de valvulopathie. Un BIA augmente le risque d'arythmie, d'AVC, de dysfonction ventriculaire et de mortalité. Identifier une altération de l'onde P a une importance pronostique et doit susciter la recherche de pathologies associées.