New electrocardiographic aspects of the P wave: Its value in clinical cardiology.

In this article, we will comment on new aspects of P-wave morphology that help us to better diagnose atrial blocks and atrial enlargement, and their clinical implications. These include: (1) Atypical ECG patterns of advanced interatrial block; (2) The ECG diagnosis of left atrial enlargement versus interatrial block; (3) Atrial fibrillation and advanced interatrial block: The two sides of the same coin; and (4) P-wave parameters: Clinical implications.

Interatrial block can occur in the absence of left atrial enlargement: New experimental model.

We present the surface electrocardiogram of an open-chest anesthetized healthy adult swine after direct application of ice at the transversus sinus of the pericardium where the Bachmann's region is located. Gradual and transient interatrial block (IAB) in the absence of structural atrial disease is described. This new experimental model demonstrated that IAB is an independent entity from left atrial enlargement.

A counterpoint paper: Comments on the electrocardiographic part of the 2018 Fourth Universal Definition of Myocardial Infarction endorsed by the International Society of Electrocardiology and the International Society for Holter and Noninvasive Electrocardiology.

The Fourth Universal Definition of Myocardial Infarction (FUDMI) focuses on the distinction between nonischemic myocardial injury and myocardial infarction (MI), along with the role of cardiovascular magnetic resonance, in order to define the etiology of myocardial injury. As a consequence, there is less emphasis on updating the parts of the definition concerning the electrocardiographic (ECG) changes related to MI. Evidence of myocardial ischemia is a prerequisite for the diagnosis of MI, and the ECG is the main available tool for (a) detecting acute ischemia, (b) triage, and (c) risk stratification upon presentation. This review focuses on multiple aspects of ECG interpretation that we firmly believe should be considered for incorporation in any future update to the Universal Definition of MI.

Prognostic of Interatrial Block after an Acute ST-Segment Elevation Myocardial Infarction.

BACKGROUND: The influence of interatrial block (IAB) in the prognosis after an acute ST-segment elevation myocardial infarction (STEMI) is unknown. OBJECTIVES: To assess the prognostic impact of IAB after an acute STEMI regarding long-term mortality, development of atrial fibrillation, and stroke. METHODS: Registry of 972 consecutive patients with STEMI and sinus rhythm at discharge, with a long-term follow-up (49.6 ± 24.9 months). P wave duration was analyzed using digital calipers, and patients were divided into three groups: normal P wave duration (<120 ms), partial IAB (pIAB) (P wave ≥120 ms and positive in inferior leads), and advanced IAB (aIAB) (P wave ≥120 ms plus biphasic [positive/negative] morphology in inferior leads). RESULTS: Mean age was 62.6 ± 13.5 years. A total of 708 patients had normal P wave (72.8%), 207 pIAB (21.3%), and 57 aIAB (5.9%). Patients with aIAB were older (mean age 73 years) than the rest (62 years in the other two groups, p < 0.001). They also had a higher rate of hypertension (70 vs. 55% in pIAB and 49% in normal P wave, p = 0.006) and higher all-cause mortality (26.3 vs. 12.6% in pIAB and 10.3% in normal P wave, p = 0.001). However, multivariable analysis did not show an independent association between IAB and prognosis. CONCLUSION: About a quarter of patients discharged in sinus rhythm after an acute STEMI have IAB. Patients with aIAB have a poor prognosis, although this is explained mainly by the association of aIAB with age and other variables.

Upsloping ST depression: Is it acute ischemia?

We describe a patient with acute coronary syndrome, presenting with upsloping ST depression in leads I, II, V3-V6 and ST elevation in lead aVR. Coronary angiography revealed spontaneous dissection in a big, dominant left circumflex artery. No other lesions identified. During stenting of the dissection site, the distal left circumflex, supplying a large posterior descending artery was occluded, resulting in ST elevation myocardial infarction with ST elevation in lead III and aVF, but not II. This pattern is considered to represent right coronary artery infarction, rather than left circumflex infarction.

New electrocardiographic score for the prediction of atrial fibrillation: The MVP ECG risk score (morphology-voltage-P-wave duration).

BACKGROUND: Atrial fibrillation (AF) is the most common arrhythmia and has significant morbidity. A score composed of easily measured electrocardiographic variables to identify patients at risk of AF would be of great value in order to stratify patients for increased monitoring and surveillance. The purpose of this study was to develop an electrocardiographic risk score for new-onset AF. METHODS: A total of 676 patients without previous AF undergoing coronary angiography were retrospectively studied. Points were allocated based on P-wave morphology in inferior leads, voltage in lead 1, and P-wave duration (MVP). Patients were divided into three risk groups and followed until development of AF or last available clinical appointment. RESULTS: Mean age was 65 years, and 68% were male. The high- and intermediate-risk groups were more likely to develop AF than the low-risk group (odds ratio [OR] 2.4, 95% confidence interval [CI] 1.3-4.4; p = 0.006 and OR 2.1, 95% CI 1.4-3.27; p = 0.009, respectively). The high-risk group had a significantly shorter mean time to development of AF (258 weeks; 95% CI 205-310 weeks) compared to the intermediate- (278 weeks; 95% CI 252-303 weeks) and low-risk groups (322 weeks 95% CI 307-338 weeks), p = 0.005. CONCLUSIONS: A simple risk score composed of easy-to-measure electrocardiographic variables can help to predict new-onset AF. Further validation studies will be needed to assess the ability of this risk score to predict AF in other populations.

Old teaching tools should not be forgotten: The value of the Lewis ladder diagram in understanding bigeminal rhythms.

As medical education evolves, some traditional teaching methods often get forgotten. For generations, the Lewis ladder diagram (LLD) has helped students understand the mechanisms of cardiac arrhythmias and conduction disorders. Similarly, clinicians have used LLDs to communicate their proposed mechanisms to their colleagues and trainees. In this article, we revisit this technique of constructing the LLD and demonstrate this process by describing the mechanisms of various bigeminal rhythms.

Arrhythmogenic right ventricular dysplasia/cardiomyopathy: an electrocardiogram-based review.

Arrhythmogenic right ventricular dysplasia or cardiomyopathy (ARVD/C) is a pathologic condition where the right ventricle is partially or totally replaced by fatty and fibrous tissue. The electrocardiogram (ECG) has a central role for diagnosis since it comprises two major and two minor criteria in the diagnostic criteria published by the Task 1 Force, although it is not 100% necessary to make a final diagnosis, because around 10% of patients with ARVD/C present with a normal ECG. In this article, we review the 12-lead electrocardiographic findings of patients with ARVD/C. ECG criteria observed during depolarization [prolonged terminal activation duration, epsilon wave, partial right bundle branch block (RBBB) and advanced RBBB of peripheral origin with characteristic ECG patterns] and repolarization abnormalities, (negative T waves) are reviewed in detail. More common ventricular arrhythmias and risk of sudden death, and how to use the surface ECG to stratify the risk, are part of our final comments.

Atypical advanced interatrial blocks: Definition and electrocardiographic recognition.

The diagnosis of advanced interatrial block (A-IAB) is done by surface ECG analysis when the P-wave ≥120 ms with biphasic (±) morphology in leads II, III and aVF. In this brief communication, we advance a new concept involving atypical patterns of A-IAB due to changes about the morphology or duration of the P-wave. It remains to be determined its real prevalence in different clinical scenarios, and whether these atypical ECG patterns should be considered as predictors of atrial fibrillation/stroke.

Surface ECG interatrial block-guided treatment for stroke prevention: rationale for an attractive hypothesis.

Atrial fibrillation (AF) is the most common sustained arrhythmia and is associated with stroke, cognitive impairment, and cardiovascular death. Some predisposing factors - as aging, diabetes, hypertension - induce and maintain electrophysiological and ultrastructural remodeling that usually includes fibrosis. Interatrial conduction disturbances play a crucial role in the initiation of atrial fibrosis and in its associated complications. The diagnosis of interatrial blocks (IABs) is easy to perform using the surface ECG. IAB is classified as partial when the P wave duration is ≥120 ms, and advanced if the P wave also presents a biphasic pattern in II, III and aVF. IAB is very frequent in the elderly and, particularly in the case of the advanced type, is associated with AF, AF recurrences, stroke, and dementia. The anticoagulation in elderly patients at high risk of AF without documented arrhythmias is an open issue but recent data suggest that it might have a role, particularly in elderly patients with structural heart disease, high CHA2DS2VASc (Congestive heart failure/left ventricular dysfunction, Hypertension, Age ≥ 75 [doubled], Diabetes, Stroke [doubled] - Vascular disease, Age 65-74, and Sex category [female]), and advanced IAB. In this debate, we discuss the association of surface ECG IAB, a marker of atrial fibrosis, with AF and stroke. We also present the rationale that justifies further studies regarding anticoagulation in some of these patients.

Anticoagulation in patients at high risk of stroke without documented atrial fibrillation. Time for a paradigm shift?

Atrial fibrillation (AF) is currently considered a risk factor for stroke. Depending on the severity of clinical factors (risk scores) a recommendation for full anticoagulation is made. Although AF is most certainly a risk factor for ischemic stroke, it is not necessarily the direct cause of it. The causality of association between AF and ischemic stroke is questioned by the reported lack of temporal relation between stroke events and AF paroxysms (or atrial high-rate episodes detected by devices). In different studies, only 2% of patients had subclinical AF > 6 minutes in duration at the time of stroke or systemic embolism. Is it time to consider AF only one more factor of endothelial disarray rather than the main contributor to stroke? In this "opinion paper" we propose to consider not only clinical variables predicting AF/stroke but also electrocardiographic markers of atrial fibrosis, as we postulate this as a strong indicator of risk of AF/stroke. We ask if it is time to change the paradigm and to consider, in some special situations, to protect patients (preventing stroke) who have no evidence of AF.

Differential diagnosis of rSr' pattern in leads V1 -V2. Comprehensive review and proposed algorithm.

One of the more frequent dilemmas in ECG interpretation is the differential diagnosis of an rSr' pattern in leads V1 -V2 . We often face this finding in asymptomatic and otherwise healthy individuals and the causes may vary from benign nonpathological variants to severe or life-threatening heart diseases, such as Brugada syndrome or arrhythmogenic right ventricular dysplasia. In other cases, a normal variant of rSr' pattern can be misinterpreted as pathological after the occurrence of certain clinical events such as cardiac arrest or syncope of unknown cause. In this review we analyze in detail all the possible conditions, both benign and pathological that may explain the presence of this electrocardiographic pattern. We also propose a simple electrocardiographic algorithm for differential diagnosis.

Advanced Interatrial Block Predicts New Onset Atrial Fibrillation in Patients with Severe Heart Failure and Cardiac Resynchronization Therapy.

BACKGROUND: Advanced interatrial block (aIAB) on the surface electrocardiogram (ECG), defined as a P-wave duration ≥120 milliseconds with biphasic (±) morphology in inferior leads, is frequently associated with atrial fibrillation (AF). The aim of this study was to determine whether preoperative aIAB could predict new-onset AF in patients with severe congestive heart failure (CHF) requiring cardiac resynchronization therapy (CRT). METHODS: Retrospective analysis of consecutive patients with CHF and no prior history of AF undergoing CRT for standard indications. A baseline 12-lead ECG was obtained prior to device implantation and analyzed for the presence of aIAB. ECGs were scanned at 300 DPI and maximized 8×. Semiautomatic calipers were used to determine P-wave onset and offset. The primary outcome was the occurrence of AF identified through analyses of intracardiac electrograms on routine device follow-up. RESULTS: Ninety-seven patients were included (74.2% male, left atrial diameter 45.5 ± 7.8 mm, 63% ischemic). Mean P-wave duration was 138.5 ± 18.5 milliseconds and 37 patients (38%) presented aIAB at baseline. Over a mean follow-up of 32 ± 18 months, AF was detected in 29 patients (30%) and the incidence was greater in patients with aIAB compared to those without it (62% vs 28%; P < 0.003). aIAB remained a significant predictor of AF occurrence after multivariate analysis (OR 4.1; 95% CI, 1.6-10.7; P < 0.003). CONCLUSION: The presence of aIAB is an independent predictor of new-onset AF in patients with severe CHF undergoing CRT.

New electrocardiographic criteria to differentiate the Type-2 Brugada pattern from electrocardiogram of healthy athletes with r'-wave in leads V1/V2.

AIMS: Diagnosis of Type-2 Brugada pattern remains challenging and it could be confused with other electrocardiogram (ECG) patterns presenting an r'-wave in leads V1-V2 like in healthy athletes. This could impact their ability to perform competitive sports. The aim of the study was to evaluate, as a proof of concept, the new ECG criteria to differentiate the Type-2 Brugada pattern from the ECG pattern of healthy athletes depicting an r'-wave in leads V1-V2. METHODS AND RESULTS: Surface ECGs from 50 patients with Brugada syndrome and type-2 Brugada pattern and 58 healthy athletes with an r'-wave in leads V1-V2 were analysed. Different criteria based on the characteristics of the triangle formed by the ascendant and descendant arms of the r'-wave in leads V1-V2 were compared. The duration of the base of the triangle at 0.5 mV (5 mm) from high take-off ≥160 ms (4 mm) has a specificity (SP) of 95.6%, sensitivity (SE) 85%, positive predictive value (PPV) 94.4%, and negative predictive value (NPV) 87.9%. The duration of the base of the triangle at the isoelectric line ≥60 ms (1.5 mm) in leads V1-V2 has an SP of 78%, SE 94.8%, PPV 79.3%, and NPV 93.5%. The ratio of the base at isoelectric line/height from the baseline to peak of r'-wave in leads V1-V2 has an SP of 92.1%, SE 82%, PPV 90.1%, and NPV 83.3%. CONCLUSIONS: The three new ECG criteria were accurate to distinguish the Type-2 Brugada pattern from the ECG pattern with an r'-wave in healthy athletes. The duration of the base of the triangle at 0.5 mV from the high take-off is the easiest to measure and may be used in clinical practice.

Interatrial Block Association With Adverse Cardiovascular Outcomes in Patients Without a History of Atrial Fibrillation.

BACKGROUND: Interatrial block (IAB) is associated with thromboembolism and atrial arrhythmias. However, prior studies included small patient cohorts so it remains unclear whether IAB predicts adverse outcomes particularly in context of atrial fibrillation (AF)/atrial flutter (AFL). OBJECTIVES: This study sought to determine whether IAB portends increased stroke risk in a large cohort in the presence or absence of AFAF/AFL. METHODS: We performed a 5-center retrospective analysis of 4,837,989 electrocardiograms (ECGs) from 1,228,291 patients. IAB was defined as P-wave duration ≥120 ms in leads II, III, or aVF. Measurements were extracted as .XML files. After excluding patients with prior AF/AFL, 1,825,958 ECGs from 458,994 patients remained. Outcomes were analyzed using restricted mean survival time analysis and restricted mean time lost. RESULTS: There were 86,317 patients with IAB and 355,032 patients without IAB. IAB prevalence in the cohort was 19.6% and was most common in Black (26.1%), White (20.9%), and Hispanic (18.5%) patients and least prevalent in Native Americans (9.2%). IAB was independently associated with increased stroke probability (restricted mean time lost ratio coefficient [RMTLRC]: 1.43; 95% CI: 1.35-1.51; tau = 1,895), mortality (RMTLRC: 1.14; 95% CI: 1.07-1.21; tau = 1,924), heart failure (RMTLRC: 1.94; 95% CI: 1.83-2.04; tau = 1,921), systemic thromboembolism (RMTLRC: 1.62; 95% CI: 1.53-1.71; tau = 1,897), and incident AF/AFL (RMTLRC: 1.16; 95% CI: 1.10-1.22; tau = 1,888). IAB was not associated with stroke in patients with pre-existing AF/AFL. CONCLUSIONS: IAB is independently associated with stroke in patients with no history of AF/AFL even after adjustment for incident AF/AFL and CHA2DS2-VASc score. Patients are at increased risk of stroke even when AF/AFL is not identified.

Cardiovascular Complications of Interatrial Conduction Block: JACC State-of-the-Art Review.

Interatrial block (IAB) is an electrocardiographic pattern describing the conduction delay between the right and left atria. IAB is classified into 3 degrees of block that correspond to decreasing conduction in the region of Bachmann's bundle. Although initially considered benign in nature, specific subsets of IAB have been associated with atrial arrhythmias, elevated thromboembolic stroke risk, cognitive impairment, and mortality. As the pathophysiologic relationships between IAB and stroke are reinforced, investigation has now turned to the potential benefit of early detection, atrial imaging, cardiovascular risk factor modification, antiarrhythmic pharmacotherapy, and stroke prevention with oral anticoagulation. This review provides a contemporary overview of the epidemiology, pathophysiology, diagnosis, and management of IAB, with a focus on future directions.