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Premature ventricular complexes (PVCs) are encountered frequently in clinical practice. While PVCs may have various causes, a small number of individuals with PVCs develop cardiomyopathy in the absence of other potential etiologies. When correctly identified, patients with PVC‐incuded cardiomyopathy can have dramatic improvement of their cardiomyopathy with treatment of their PVCs. In this focused review, we discuss potential predictors of PVC‐induced cardiomyopathy, including PVC frequency, PVC characteristics, and modifiable patient risk factors. We also review some proposed mechanisms of PVC‐induced cardiomyopathy and conclude with future directions for research and clinical practice. [ABSTRACT FROM AUTHOR]

Oral nirmatrelvir/ritonavir is approved as treatment for acute COVID‐19, but the effect of treatment during acute infection on risk of Long COVID is unknown. We hypothesized that nirmatrelvir treatment during acute SARS‐CoV‐2 infection reduces risk of developing Long COVID and rebound after treatment is associated with Long COVID. We conducted an observational cohort study within the Covid Citizen Science (CCS) study, an online cohort study with over 100 000 participants. We included vaccinated, nonhospitalized, nonpregnant individuals who reported their first SARS‐CoV‐2 positive test March–August 2022. Oral nirmatrelvir/ritonavir treatment was ascertained during acute SARS‐CoV‐2 infection. Patient‐reported Long COVID symptoms, symptom rebound and test‐positivity rebound were asked on subsequent surveys at least 3 months after SARS‐CoV‐2 infection. A total of 4684 individuals met the eligibility criteria, of whom 988 (21.1%) were treated and 3696 (78.9%) were untreated; 353/988 (35.7%) treated and 1258/3696 (34.0%) untreated responded to the Long COVID survey (n = 1611). Among 1611 participants, median age was 55 years and 66% were female. At 5.4 ± 1.3 months after infection, nirmatrelvir treatment was not associated with subsequent Long COVID symptoms (odds ratio [OR]: 1.15; 95% confidence interval [CI]: 0.80–1.64; p = 0.45). Among 666 treated who answered rebound questions, rebound symptoms or test positivity were not associated with Long COVID symptoms (OR: 1.34; 95% CI: 0.74–2.41; p = 0.33). Within this cohort of vaccinated, nonhospitalized individuals, oral nirmatrelvir treatment during acute SARS‐CoV‐2 infection and rebound after nirmatrelvir treatment were not associated with Long COVID symptoms more than 90 days after infection. [ABSTRACT FROM AUTHOR]

In‐hospital electrocardiographic (ECG) monitors are typically configured to alarm for premature ventricular complexes (PVCs) due to the potential association of PVCs with ventricular tachycardia (VT). However, no contemporary hospital‐based studies have examined the association of PVCs with VT. Hence, the benefit of PVC monitoring in hospitalized patients is largely unknown. This secondary analysis used a large PVC alarm data set to determine whether PVCs identified during continuous ECG monitoring were associated with VT, in‐hospital cardiac arrest (IHCA), and/or death in a cohort of adult intensive care unit patients. Six PVC types were examined (i.e., isolated, bigeminy, trigeminy, couplets, R‐on‐T, and run PVCs) and were compared between patients with and without VT, IHCA, and/or death. Of 445 patients, 48 (10.8%) had VT; 11 (2.5%) had IHCA; and 49 (11%) died. Isolated and run PVC counts were higher in the VT group (p = 0.03 both), but group differences were not seen for the other four PVC types. The regression models showed no significant associations between any of the six PVC types and VT or death, although confidence intervals were wide. Due to the small number of cases, we were unable to test for associations between PVCs and IHCA. Our findings suggest that we should question the clinical relevance of activating PVC alarms as a forewarning of VT, and more work should be done with larger sample sizes. A more precise characterization of clinically relevant PVCs that might be associated with VT is warranted. [ABSTRACT FROM AUTHOR]

Coffee's effects on cardiac arrhythmias, physical activity, sleep and serum glucose: Insights from the Coffee and Real-time Atrial and Ventricular Ectopy trial In contrast, random assignment to coffee was associated with about 50% more PVCs, and those consuming more than 1 drink of coffee had a doubling of their PVCs (both statistically significant). Coffee is one of the most commonly consumed beverages in the world, and yet the majority of research investigating the health effects have been limited to either observational studies prone to confounding or small laboratory-based studies in artificial settings focused on single doses of caffeine. [Extracted from the article]

Introduction: Some patients have late recurrence after acutely successful radiofrequency catheter ablation (RFCA) of premature ventricular complexes (PVCs). The aim of this study was to evaluate predictors of long‐term success following acutely successful PVC RFCA. Methods: We identified consecutive patients at our institution with frequent PVCs undergoing RFCA and reviewed procedural data and medical records. Acute success was defined as elimination of targeted PVCs for at least 30‐min after RFCA. Long‐term success was defined as absence of targeted PVCs during all follow‐up visits and PVC‐burden <5% on follow‐up monitoring. Results: Among 241 patients (mean age 57 ± 15 years, 58% male), 161 (66.8%) had long‐term success with median follow‐up of 17.7 (IQR, 12.2–29.8) months. Unadjusted predictors of late PVC recurrence were increasing age, diabetes mellitus and alcohol use, while female‐sex, shorter ablation‐time, right ventricular PVC‐origin, single PVC morphology, and earliest bipolar activation ≥24 ms pre‐QRS were predictors of long‐term success. In multivariate‐analysis, female‐sex, single‐PVC morphology and earliest‐onset of PVC ≥ 24 ms pre‐QRS were independent predictors for long‐term success. The positive‐predictive value of earliest‐bipolar onset of PVC ≥ 24 ms pre‐QRS for long‐term success was 0.77 (p <.001). Negative‐predictive value of PVC < 15 ms pre‐QRS for long‐term success was 0.86 (p =.003), suggesting that RFCA when the bipolar electrogram preceded QRS by <15 ms was unlikely to result in long‐term success. Conclusions: Female‐sex, single‐PVC morphology, and earliest‐onset of bipolar electrogram ≥24 ms pre‐QRS were multivariable predictors of long‐term success in patients with PVCs undergoing RFCA. RFCA at sites with local onset <15 ms pre‐QRS are unlikely to be successful. [ABSTRACT FROM AUTHOR]

Background: Objective measurement of alcohol consumption is important for clinical care and research. Adjusting for self‐reported alcohol use, we conducted an individual participant data (IPD) meta‐analysis to examine factors associated with the sensitivity of phosphatidylethanol (PEth), an alcohol metabolite, among persons self‐reporting unhealthy alcohol consumption. Methods: We identified 21 eligible studies and obtained 4073 observations from 3085 participants with Alcohol Use Disorders Identification Test—Consumption (AUDIT‐C) positive scores (≥3 for women and ≥4 for men) and PEth measurements. We conducted 1‐step IPD meta‐analysis using mixed effects models with random intercepts for study site. We examined the associations between demographic (sex, race/ethnicity, and age) and biologic (body mass index—BMI, hemoglobin, HIV status, liver fibrosis, and venous versus finger‐prick blood collection) variables with PEth sensitivity (PEth≥8 ng/ml), adjusting for the level of self‐reported alcohol use using the AUDIT‐C score. Results: One third (31%) of participants were women, 32% were African, 28% African American, 28% White, and 12% other race/ethnicity. PEth sensitivity (i.e., ≥8 ng/ml) was 81.8%. After adjusting for AUDIT‐C, we found no associations of sex, age, race/ethnicity, or method of blood collection with PEth sensitivity. In models that additionally included biologic variables, those with higher hemoglobin and indeterminate and advanced liver fibrosis had significantly higher odds of PEth sensitivity; those with higher BMI and those living with HIV had significantly lower odds of PEth sensitivity. African Americans and Africans had higher odds of PEth sensitivity than whites in models that included biologic variables. Conclusions: Among people reporting unhealthy alcohol use, several biological factors (hemoglobin, BMI, liver fibrosis, and HIV status) were associated with PEth sensitivity. Race/ethnicity was associated with PEth sensitivity in some models but age, sex, and method of blood collection were not. Clinicians should be aware of these factors, and researchers should consider adjusting analyses for these characteristics where possible. [ABSTRACT FROM AUTHOR]

Introduction: Cardiac adaptation to sustained exercise in the athletes is established. However, exercise‐associated effect on the cardiac function of the elderly has to be elucidated. The aim of this study was to analyse left (LV) and right ventricular (RV) characteristics at different levels of chronic exercise in the senior heart. Materials and methods: We studied 178 participants in the World Senior Games (mean age 68 ± 8 years, 86 were men; 48%). Three groups were defined based on the type and intensity of sports: low‐, moderate‐ and high‐intensity level. Exclusion criteria were coronary artery disease, atrial fibrillation, valvular heart disease or uncontrolled hypertension. LV and RV size and function were evaluated with an echocardiogram. Results: LV trans‐mitral inflow deceleration time decreased in parallel to the intensity of chronic exercise: 242 ± 54 ms in low‐, 221 ± 52 ms in moderate‐ and 215 ± 58 ms in high‐intensity level, p =.03. Left atrial volume index (LAVI) was larger in high‐intensity group, p =.001. The LAVI remained significantly larger when adjusting for age, gender, heart rate, hypertension and diabetes (p =.002). LV and RV sizes were larger in the high‐intensity group. LV ejection fraction and RV systolic function evaluated by tissue Doppler velocity, atrioventricular plane displacement and strain did not differ between groups. Conclusion: Left ventricular diastolic filling is not only preserved, but may also be enhanced in long‐term, top‐level senior athletes. Moreover, LV and RV systolic function remain unchanged at different levels of exercise. This supports the beneficial effects of endurance exercise participation in senior hearts. [ABSTRACT FROM AUTHOR]

Introduction: Transseptal puncture is an integral step in various catheter‐based cardiac procedures and can be performed with either the conventional mechanical needle or an FDA‐cleared device utilizing radiofrequency (RF) energy. Although a previous randomized trial suggested that the RF transseptal device may be faster and more often successful, the increased equipment costs may dissuade operators from routine use. This analysis compares the cost‐effectiveness of the mechanical needle to the RF device during pulmonary vein isolation. Methods: The rates of successful transseptal punctures for each device and transseptal‐related complications were determined from the peer‐reviewed medical literature. Procedural, equipment, and complication costs were obtained from peer‐reviewed medical literature and the Healthcare Cost and Utilization Project. The effectiveness was defined as the probability of 30‐day survival following a successful transseptal puncture. Monte Carlo probabilistic analyses tested variable effects of costs and complication rates on the incremental cost‐effectiveness ratio. Results: The 30‐day effectiveness of the RF device vs the mechanical needle was 99.7% and 98.8%, respectively. After accounting for all costs of performing a single transseptal puncture, the cost at 30 days associated with the RF device was $41 less than the mechanical needle ($21 096 vs $21 137). The RF device was similarly dominant to the mechanical needle in double transseptal puncture scenarios. Finally, the RF device was more cost‐effective than the mechanical needle at any willingness‐to‐pay in Monte Carlo probabilistic sensitivity analyses. Conclusions: Despite greater equipment costs, the RF device costs less and provides better effectiveness at 30 days than the conventional mechanical needle. [ABSTRACT FROM AUTHOR]

Introduction: The clinical role of atrial arrhythmias (AA) in arrhythmogenic right ventricular cardiomyopathy (ARVC) and the echocardiographic variables that predict them are not well defined. We describe the prevalence, types, echocardiographic predictors, and management of AA in patients with ARVC. Methods: We retrospectively evaluated medical records of 117 patients with definite ARVC (2010 Task Force Criteria) from two tertiary care centers. We identified those patients with sustained AA (>30 seconds), including atrial fibrillation (AF), atrial flutter (AFL), and atrial tachycardia (AT). We collected demographic, genetic, and clinical data. The median follow‐up was 3.4 years (interquartile range = 2.0‐5.7). Results: Total 26 patients (22%) had one or more types of AA: AF (n = 19), AFL (n = 9), and AT (n = 8). We performed genetic testing on 84 patients with ARVC (71.8%). Two patients with AA (8%) had peripheral emboli, and one patient (4%) suffered inappropriate implantable cardioverter‐defibrillator shock. We performed catheter ablation of AA in eight patients (31%), with no procedural complications. Right atrial area and left atrial volume index were independently associated with increased odds of AA; odds ratio (OR), 1.1 (95% confidence interval [CI]:1.02‐1.16) (P = .01) and OR, 1.1 (95% CI:1.03‐1.15) (P = .003), respectively. An increase in tricuspid annular plane peak systolic excursion was independently associated with reduced odds; OR, 0.3 (95% CI: 0.1‐0.94) (P = .003). Conclusions: Atrial arrhythmias (AA) are common in patients with arrhythmogenic right ventricular cardiomyopathy (ARVC). Inappropriate shocks and systemic emboli may be associated with AA. Atrial size and right ventricular dysfunction may help identify patients with ARVC at increased odds of AA. [ABSTRACT FROM AUTHOR]

Background: Urinary tract infection (UTI) is common after surgical procedures and a quality improvement target. For non‐surgical procedures such as catheter ablation of atrial fibrillation (AF), UTI risk has not been characterized. We sought to determine incidence and risk factors of UTI after AF ablation and risk variation across sites. Methods: Using Marketscan commercial claims databases, we performed a retrospective cohort study of patients who underwent AF ablation from 2007 to 2011. The primary outcome was UTI diagnosis within 30 days after ablation. We performed multivariate analyses to determine risk factors for UTI and risk of sepsis within 30 days after ablation with UTI as the predictor variable. Median odds ratio was used to quantify UTI site variation. Results: Among 21 091 patients (age 59.2 ± 10.9; 29.1% female; CHA2DS2‐VASc 2.0 ± 1.6), 622 (2.9%) were diagnosed with UTI within 30 days. In multivariate analyses, UTI was independently associated with age, female sex, prior UTI, and general anesthesia (all P < .01). UTI diagnosis was associated with a substantial increased risk of sepsis within 30 days (5.0% vs. 0.3%; odds ratio 17.5; 95% confidence interval [CI] 10.8‐28.2; P < .0001). Among 416 sites, 211 had at least one UTI. Among these 211 sites, the incidence of postablation UTI ranged from 0.7 to 26.7% (median: 5.4%; Interquartile Range (IQR): 3.0‐7.1%; 95th percentile: 14.3%; median odds ratio: 1.45; 95% CI 1.41‐1.50). Conclusions: UTI after AF ablation is not uncommon and varies substantially across sites. Consideration of UTI as a quality measure and interventions targeted at high‐risk patients or sites warrant consideration. [ABSTRACT FROM AUTHOR]

Introduction: Outcome of patients undergoing catheter ablation of atrial fibrillation (AF) varies widely. We sought to investigate whether parameters derived from the spectral analysis of surface ECG and intracardiac AF electrograms can predict outcome in patients referred for pulmonary vein isolation (PVI). Methods: We performed spectral analysis on the surface ECG and intracardiac electrograms from patients referred for AF ablation. After filtering and QRST subtraction, we measured the dominant frequency (DF), regularity index (RI) and the organizational index (OI) of fibrillatory electrograms and determined their value for predicting AF recurrence after ablation. A subjective, blinded prediction based on the surface ECG was also performed. Results: We analyzed data from 153 PVI procedures in 140 patients (67.1% with persistent or longstanding AF). In a multivariable model, DF in the right atrium (RA) and distal coronary sinus (CSd)‐to‐RA DF gradient predicted AF recurrence (OR, 3.52, P = 0.023 and OR, 0.2, P = 0.034, respectively). DF in RA and CSd to RA DF gradient had a good predictive value for PVI outcome (area under the curve [AUC] of 0.73, P = 0.007 and 0.74, P = 0.007, respectively). These performed better than the subjective predictions of experienced electrophysiologists (P = 0.2). Conclusions: Higher RA DF, lower CSd to RA DF gradient predicted recurrence after AF ablation. These spectral measures suggest a more remodeled atrial substrate and may provide simple tools for risk stratification or predict the need for additional substrate modification in patients referred for AF ablation. [ABSTRACT FROM AUTHOR]

Background The cornerstone of atrial fibrillation (AF) ablation is isolation of the pulmonary veins (PVs). Patients with recurrent AF undergoing repeat ablation usually have PV reconnection (PVr). The ablation strategy and outcome of patients undergoing repeat ablation who have persistent isolation of all PVs (PVi) at the time of repeat ablation is unknown. Methods and results We studied consecutive patients with recurrent AF undergoing repeat ablation and compared patients with PVi to those with PVr. One hundred fifty-two patients underwent repeat ablation, and of these, 25 patients (16.4%) had PVi. Patients with PVi underwent ablation targeting any isoproterenol induced AF triggers, atrial substrate, or inducible atrial tachycardias or flutters. Patients with PVi compared to PVr were more likely to have a history of persistent AF (64% vs. 26%; P < 0.0001), obesity (BMI 30.4 vs. 28.2; P = 0.05), and prior use of contact force sensing catheters (28% vs. 0.8%, P < 0.0001). After a mean follow-up of 19 ± 15 months, 56% of PVi patients remained in sinus rhythm compared to 76.3% of PVr patients (P = 0.036). In a multivariable model, PVi patients and those with cardiomyopathy had a higher risk of recurrent atrial tachyarrhythmias (HR = 3.6 95%, CI 1.6-8.3, P = 0.002 and HR = 6.2, 95% CI 2.3-16.3, P < 0.0001, respectively). Conclusion In patients who have all PVs isolated at the time of the redo AF ablation, a strategy of targeting non-PV AF triggers and inducible flutters can still lead to AF freedom in more than half of patients. Patients with PVr, however, have a better long-term outcome. [ABSTRACT FROM AUTHOR]

Background Atrioventricular reciprocating tachycardia (AVRT) utilizing a concealed accessory pathway is common. It is well appreciated that some patients may have multiple accessory pathways with separate atrial and ventricular insertion sites. Methods We present three cases of AVRT utilizing concealed pathways with evidence that each utilizing a single ventricular insertion and two discrete atrial insertion sites. Results In case one, two discrete atrial insertion sites were mapped in two separate procedures, and only during the second ablation was the Kent potential identified. Ablation of the Kent potential at this site remote from the two atrial insertion sites resulted in the termination of the retrograde conduction in both pathways. Case two presented with supraventricular tachycardia (SVT) with alternating eccentric atrial activation patterns without alteration in the tachycardia cycle length. The two distinct atrial insertion sites during orthodromic AVRT and ventricular pacing were targeted and each of the two atrial insertion sites were successfully mapped and ablated. In case three, retrograde decremental conduction utilizing both atrial insertion sites was identified prior to ablation. After mapping and ablation of the first discrete atrial insertion site, tachycardia persisted utilizing the second atrial insertion site. Only after ablation of the second atrial insertion site was SVT noninducible, and VA conduction was no longer present. Conclusions Concealed retrograde accessory pathways with discrete atrial insertion sites may have a common ventricular insertion site. Identification and ablation of the ventricular insertion site or the separate discrete atrial insertion sites result in successful treatment. [ABSTRACT FROM AUTHOR]

Background Atrial refractoriness may be an important determinant of atrial fibrillation (AF) risk, but its measurement is not clinically accessible. Because the QT interval predicts incident AF and the atrium and ventricle share repolarizing ion currents, we investigated the association between an individual's QT interval and atrial effective refractory period (AERP). Methods In paroxysmal AF patients presenting for catheter ablation, the QT interval was measured from the surface 12-lead electrocardiogram. The AERP was defined as the longest S1-S2 coupling interval without atrial capture using a 600-ms drive cycle length. Results In 28 patients, there was a positive correlation between QTc and mean AERP. After multivariate adjustment, a 1-ms increase in QTc predicted a 0.70-ms increase in AERP. Conclusions The QTc interval reflects the AERP, suggesting that the QTc interval may be used as a marker of atrial refractoriness relevant to assessing AF risk and mechanism-specific therapeutic strategies. [ABSTRACT FROM AUTHOR]

Molecular Sub-Phenotypes of Atrial Fibrillation Introduction Genome wide association studies have identified several single nucleotide polymorphisms (SNPs) associated with atrial fibrillation (AF), but the mechanisms underlying these relationships have not yet been elucidated. Inflammation and fibrosis have been posited as important mechanisms responsible for AF. We sought to investigate the impact of SNP carrier status on inflammation and fibrosis in left atrial appendage tissue. Methods and Results Carrier status of 10 AF-associated SNPs was evaluated on DNA extracted from left atrial appendage tissue in 176 individuals (120 with AF). The presence of inflammation was evaluated through visual quantification of leukocyte infiltration following hematoxylin and eosin staining, while fibrosis was quantified using picrosirius red with fast green staining. Unadjusted and adjusted linear and logistic regression models were utilized to evaluate for an association between SNP carrier status and inflammation and fibrosis. On adjusted logistic regression analysis, the rs7164883 SNP (intronic within HCN4) was associated with a reduced odds of inflammation (odds ratio: 0.42; 95% CI: 0.22-0.81, P = 0.01), and was not associated with fibrosis on adjusted linear regression analysis (β-coefficient: -0.31; 95% CI: -1.03-0.40, P = 0.40). None of the remaining SNPs exhibited significant associations with left atrial inflammation or fibrosis. Conclusions Among 10 AF-associated SNPs, a single genetic variant was associated with reduced left atrial inflammation, while no histologic differences were observed in the remaining 9. The known AF-associated SNPs do not appear to predispose to the development of pro-inflammatory or pro-fibrotic AF sub-phenotypes. [ABSTRACT FROM AUTHOR]

Introduction There are several methods to induce ventricular fibrillation (VF) during defibrillation threshold (DFT) testing. Delivering a shock at a critical time during the T wave (T-shock) is the conventional approach, while delivering a constant direct current voltage (DC stim) from the implantable cardioverter defibrillator is an alternative method. Only a few reports compare VF induction methods. The purpose of this study was to evaluate the effects and safety of DC stim versus T-shock. Methods We retrospectively investigated 414 consecutive patients undergoing DFT testing. We compared the two groups (DC stim and T-shock) with respect to clinical characteristics, electrocardiogram (ECG) changes, and complications. Results Ventricular arrhythmia, including ventricular tachycardia (VT) and VF, was induced by DC stim in 93 patients or T-shock in 321 patients. No more than three attempts were performed during one procedure. There was no significant difference in the baseline ECG, induced tachycardia cycle length (TCL), or complications between the two groups. However, the induced TCL was significantly shorter than the clinical TCL regardless of induction method (P = 0.001). Five patients suffered major complications (i.e., electromechanical dissociation or incessant VT). A history of atrial fibrillation was significantly greater in patients with major complications than the others (80% vs 24%, P = 0.004), and was an independent predictor on multivariate analysis. Conclusions There is no significant difference in induced TCL or complications between the DC stim and T-shock. The induced TCL is significantly shorter than clinical TCL regardless of induction method. [ABSTRACT FROM AUTHOR]

Background High-burden premature ventricular contractions (PVCs) may be an important determinant of heart failure (HF) in patients presenting for PVC ablation. The prevalence and characteristics of high-burden PVC patients outside this setting remain unknown. We, therefore, sought to determine predictors of high-burden PVCs and, among high-burden PVC patients, predictors of HF. Methods We identified all patients undergoing a 24-48-hour Holter study showing at least 20% PVCs between 2005 and 2013 at the University of California, San Francisco. Three time-matched controls undergoing Holter monitoring were selected for each high-burden PVC patient. Medical records were reviewed and test characteristics of PVC counts from 12-lead electrocardiograms (ECG) as predictors of high-burden PVC Holters were analyzed. Results Among 5,091 participants, 66 (1.3%) exhibited at least 20% PVCs. After multivariate adjustment, high-burden PVC patients had a three-fold greater odds of HF (odds ratio [OR] 3.15; 95% confidence interval [CI] 1.28-6.50; P = 0.005) and 10-fold greater odds of having a first-degree family member with sudden death (OR 9.97; 95% CI 1.78-60.8; P = 0.011). The C-statistic for the number of PVCs on 12-lead electrocardiogram as a predictor of high-burden PVCs was 0.7949. Among high-burden PVC patients, HF was associated with a history of coronary artery bypass grafting (OR 11.76; 95% CI 1.30-106.49; P = 0.028). Conclusion Among all undergoing Holter monitoring, 1.3% exhibited high-burden PVCs, a phenomenon associated with HF and a first-degree family history of sudden death. In an analysis restricted to high-burden PVC patients, a history of coronary artery bypass grafting was a predictor of HF. [ABSTRACT FROM AUTHOR]

Background A recent study using an anti-plakoglobin antibody and immunofluorescence methods in endomyocardial tissue specimens found that a marked reduction in plakoglobin staining was highly sensitive and specific for the diagnosis of arrhythmogenic right ventricular cardiomyopathy (ARVC). The purpose of our study was to determine the diagnostic utility of plakoglobin immunolocalization using more standard immunoperoxidase methods suitable for clinical laboratories. Methods Between January 2007 and October 2010, all patients at our center with suspected ARVC underwent noninvasive and genetic testing, right ventricular (RV) angiography, electrophysiologic studies, and endomyocardial biopsy from the RV septum. Several studies using anti-plakoglobin antibodies were performed using standard immunoperoxidase methods at concentrations of 1:50,000 and 1:75,000 after serial dilutions. Results Among 16 patients, nine patients fulfilled the clinical criteria for ARVC, and seven patients were found to have other cardiac diagnoses. In the initial study (1:50,000) only one of nine ARVC patients showed reduced plakoglobin signal while the others had normal staining. On repeat staining (1:75,000), reduced signal was observed in three of five of the ARVC patients compared to none in controls (four patients did not have adequate tissue for the repeat experiment). Conclusion These results confirm that abnormal plakoglobin staining can differentiate biopsies from patients with ARVC from those with other myopathies, but with low sensitivity. Further, each specimen must be studied at a particular concentration due to variable antibody reactivity. The necessity for such fine-tuning of the reaction, as well as the subjectivity involved in interpretation of the results, would make this method difficult to utilize in routine hospital laboratories. [ABSTRACT FROM AUTHOR]

rs7629265 and AF Risk Objective We examined the association of rs7626962 (S1103Y) or rs7629265, a variant in high linkage disequilibrium with S1103Y (r2 = 0.87 - 1), with sudden cardiac death (SCD) and atrial fibrillation (AF) among African Americans. Background The SCN5A missense variant S1103Y has been associated with SCD among African Americans in small case-control studies, but larger population-based studies are needed to validate these findings. The association of this variant with AF has not been fully explored. Methods Using genotyping data on over 7,000 African Americans from 5 cohorts (Atherosclerosis Risk in Communities [ARIC], Cleveland Family Study [CFS], Jackson Heart Study [JHS], Multi-Ethnic Study of Atherosclerosis [MESA], Cardiovascular Health Study [CHS]), we examined the association of rs7629265 with electrocardiographic PR, QRS, and QT intervals, and with incident AF and SCD. We examined association of S1103Y (rs7626962) with SCD using a population-based case-control study of SCD Cardiac Arrest Blood Study (CABS). Results Meta-analyses across 5 cohorts demonstrated that rs7629265 was significantly associated with PR duration (β = −4.1 milliseconds; P = 2.2×10−6), but not significantly associated with QRS or QT intervals. In meta-analyses of prospectively followed ARIC and CHS participants (n = 3,656), rs7629265 was associated with increased AF risk (n = 299 AF cases; HR = 1.74, P = 1.9 × 10−4). By contrast, rs7629265 was not significantly associated with SCD risk in ARIC (n = 83 SCD cases; P = 0.30) or CHS (n = 54 SCD cases; P = 0.47). Similarly, S1103Y was not significantly associated with SCD risk in CABS (n = 225 SCD cases; P = 0.29). Conclusion The common SCN5A variant, rs7629265, is associated with increased AF risk and shorter PR interval among African Americans. In contrast to prior reports, we found no evidence of association of rs7629265 or rs7626962 (S1103Y) with SCD risk in the general population. [ABSTRACT FROM AUTHOR]

Predictors of LV Dysfunction with Idiopathic PVC Introduction Patients with frequent premature ventricular complexes (PVCs) might be at risk for the developing or exacerbation of left ventricular (LV) dysfunction. However, some patients with a high-PVC burden do not develop cardiomyopathy, while other patients with low-PVC burden can develop cardiomyopathy. The purpose of this study was to evaluate the positive predictors of idiopathic PVCs-induced cardiomyopathy. Methods and Results We investigated 214 patients undergoing successful ablation of PVCs who had no other causes of cardiomyopathy. We divided the study cohort into 2 groups: ejection fraction (EF) ≥ 50% (normal LV) and EF < 50% (LV dysfunction). We analyzed the clinical characteristics, including the electrocardiogram and findings at electrophysiology study. Among these patients, 51 (24%) had reduced LVEF and 163 (76%) had normal LV function. Patients with LV dysfunction had significantly longer coupling interval (CI) dispersion (maximum-CI-minimum-CI) and had significantly higher PVC burden compared to those with normal LV function (CI-dispersion: 115 ± 25 milliseconds vs. 94 ± 19 milliseconds; P < 0.001; PVC burden: 19% vs. 15%; P = 0.04). Furthermore, patients with LV dysfunction had significantly higher body mass index (BMI) compared to those with normal LV function (BMI > 30 kg/m2; 37% vs. 13%; P = 0.001). Logistic regression analysis showed that CI-dispersion, PVC burden, and BMI (>30 kg/m2) are independent predictors of PVC-induced cardiomyopathy. Conclusions In addition to the PVC burden, the CI-dispersion and BMI are associated with PVC-induced cardiomyopathy. [ABSTRACT FROM AUTHOR]

Role of a 4q25 Genetic Variant in Atrial Flutter Background The prediction of atrial fibrillation (AF) following catheter ablation of atrial flutter (Afl) would be helpful to facilitate targeted arrhythmia monitoring and anti-coagulation strategies. A single nucleotide polymorphism, rs2200733, is strongly associated with AF. We sought to characterize the association between rs2200733 and prevalent Afl and to determine if the variant could predict AF after cavotricuspid isthmus ablation. Methods and Results We performed a genetic association study of 295 patients with Afl and/or AF and 469 controls using multivariable logistic regression. The variant was then assessed as a predictor of incident AF after cavotricuspid isthmus ablation in 87 consecutive typical Afl patients with Cox proportional hazards models. The rs2200733 rare allele was associated with an adjusted 2.06-fold increased odds of isolated Afl (95% CI: 1.13-3.76, P = 0.019) and an adjusted 2.79-fold increased odds of a combined phenotype of AF and Afl (95% CI: 1.81-4.28, P < 0.001). Following catheter ablation for Afl, carrier status of rs2200733 failed to predict an increased risk of AF either among all subjects (adjusted HR: 0.94; 95% CI: 0.58-1.53, P = 0.806) or among those with isolated Afl (adjusted HR: 1.29; 95% CI: 0.51-3.26, P = 0.585). Conclusions Our study demonstrates that Afl, whether occurring in isolation or along with AF, is associated with the rs2200733 AF risk allele. Genetic carrier status of rs2200733 failed to predict an increased risk of incident or recurrent AF following catheter ablation for Afl. These findings suggest that the causal mechanism associated with rs2200733 is germane to both AF and Afl. [ABSTRACT FROM AUTHOR]

Introduction Left atrial (LA) tissue characteristics may play an important role in atrial fibrillation (AF) induction and perpetuation. Although frequently used in clinical practice, computed tomography (CT) has not been employed to describe differences in LA wall properties between AF patients and controls. We sought to noninvasively characterize AF-associated differences in LA tissue using CT. Methods CT images of the LA were obtained in 98 consecutive patients undergoing AF ablation and in 89 controls. A custom software algorithm was used to measure wall thickness and density in four prespecified regions of the LA. Results On average, LA walls were thinner (−15.5%, 95% confidence interval [CI] −23.2 to −7.8%, P < 0.001) and demonstrated significantly lower density (−19.7 Hounsfield Units [HU], 95% CI −27.0 to −12.5 HU, P < 0.001) in AF patients compared to controls. In linear mixed models adjusting for demographics, clinical variables, and other CT measurements, the average LA, interatrial septum, LA appendage, and anterior walls remained significantly thinner in AF patients. After adjusting for the same potential confounders, history of AF was associated with reduced density in the LA anterior wall and increased density below the right inferior pulmonary vein and in the LA appendage. Conclusion Application of an automated measurement algorithm to CT imaging of the atrium identified significant thinning of the LA wall and regional alterations in tissue density in patients with a history of AF. These findings suggest differences in LA tissue composition can be noninvasively identified and quantified using CT. (PACE 2013; 36:55-62) [ABSTRACT FROM AUTHOR]

Background: The axillary vein is a commonly used extrathoracic access site for cardiac rhythm device lead implantation. We sought to describe variation in axillary vein location and identify predictors of a more cranial or caudal radiographic location to facilitate blind venous cannulation. Methods: This was a single-center, retrospective study of patients undergoing lead implantation between 2006 and 2010. The cranial-caudal location of the axillary vein lateral and medial to the rib cage border was determined by reviewing peripheral contrast venograms. Multivariate linear regression was performed. Results: Of 155 patients, the majority were men (62%) and White (53%). The most frequent position of the lateral and medial axillary vein was over the third rib (40%) and top of the third rib (15%), respectively. In multivariate analysis, whites had a more caudal location of both the lateral (0.56 rib spaces lower, 95% confidence interval [CI] 0.22-0.91, P = 0.002) and medial axillary vein (0.50 rib spaces lower, 95% CI 0.85-0.91, P = 0.019). Other independent predictors included an approximate 3-4% higher rib space location for every digit increase in body mass index (BMI) (P = 0.049 for the lateral location and P = 0.016 for the medial location) and an approximate half rib space higher location for males (P = 0.015 for the lateral location and P = 0.013 for the medial location). Conclusions: The most common radiographic position of the axillary vein was over the third rib. Whites have a more caudal axillary vein location while men and patients with higher BMI have a more cranial position of the axillary vein. (PACE 2011; 34:1585-1592) [ABSTRACT FROM AUTHOR]

Background: An unusual 12-lead electrocardiographic pattern may be present in patients with cavotricuspid isthmus (CTI)-dependent flutter. Objective: Using baseline patient characteristics and echocardiography, we sought to study predictors of unusual electrocardiogram (ECG) characteristics in patients with CTI-dependent atrial flutter. Methods: This was a dual-center, retrospective cohort study of 147 patients undergoing electrophysiology study and ablation for CTI-dependent atrial flutter. Results: Among this cohort, 23 patients (16%) had unusual 12-lead ECG characteristics. Using multivariate logistic regression, we found two clinical predictors for having an unusual ECG pattern. A clockwise (CW) pattern at time of electrophysiology study was the strongest predictor of an unusual ECG pattern (odds ratio 15.3, 95% confidence interval [CI] 4.0-59.4, P < 0.005). In addition, patients with decreased systolic function had a 3.5 greater odds (95% CI 1.1-11.5, P = 0.037) of having an unusual ECG pattern. Conclusions: Our data demonstrate that among patients suffering from CTI-dependent atrial flutter who are referred for ablation, 16% will have unusual ECG patterns. Patients with CW atrial activation and left ventricle dysfunction have greater odds of manifesting unusual patterns by surface electrocardiogram. (PACE 2011; 34:1251-1257) [ABSTRACT FROM AUTHOR]

Although inappropriate shocks are known to be an important consequence of implantable cardioverter-defibrillators (ICDs), the subjective experience of pain intensity perceived by those receiving inappropriate versus appropriate shocks has not previously been examined. One hundred ICD patients underwent a standardized interview by an investigator blinded to the clinical history. Patients with a previous ICD shock were asked to describe the intensity of the associated pain on a standard 0-10 scale (10 being the worst pain they had ever experienced). Medical charts were then examined for any history of inappropriate and/or appropriate ICD discharges. Thirty-five of the 100 patients had a record of at least one ICD shock, and 17 had experienced at least one inappropriate shock. Those with a history of an inappropriate shock described a significantly higher median pain scale (9, interquartile range [IQR] 8-10) compared to those with a history of only appropriate shocks (median 4, IQR 2-8, P = 0.0011). In multivariable analysis, a history of an inappropriate shock was the only predictor statistically significantly associated with an increase in shock pain: the pain scale for those with inappropriate shocks was higher by 2.8 points on average after multivariable adjustment (95% confidence interval 0.29-5, P = 0.030). Eighteen patients had considered having their device deactivated, and a history of an inappropriate shock was the only factor independently associated with this consideration. Compared to those who have received only appropriate shocks, inappropriate ICD shocks are associated with a recollection of greater pain and consideration of device inactivation. (PACE 2011; 34:348-353) [ABSTRACT FROM AUTHOR]

ECG and EGM of IIR. Introduction: Intra-isthmus reentry (IIR) is a circuit within the cavotricuspid isthmus (CTI). The purpose of this study is to prospectively define the electrogram and surface ECG characteristics of IIR, and its clinical implications. Methods and Results: Fourteen patients underwent electrophysiological studies and were found to have IIR. Detailed electrogram mapping of the CTI was available in all, electroanatomic mapping (EAM) in 8 of 14 (57%) patients. In all, entrainment mapping during tachycardia proved reentry, and showed that the anteroinferior CTI was out of the circuit and the septal CTI was in the circuit in 12 of 14 patients, whereas in 2, the circuit was confined within the mid and/or anteroinferior CTI. Fractionated potentials (FPs) spanning 34-71% of the tachycardia cycle length were recorded within the CTI in all, and double potentials were inscribed in 10 of 14 (71%). Analysis of the tricuspid annulus electrograms showed spontaneous shifts from a counterclockwise (CCW) to clockwise or fusion patterns. Surface ECGs showed either typical CCW pattern (12 patients) or atypical patterns (3 patients). The EAMs showed a focal pattern in 3, a CCW pattern in 5. The successful ablation site always occurred at the area with maximal FP duration. Over the same period, 33 of 384 (9%) patients who underwent ablation for CTI-dependent flutter had prior successful CTI ablation, 7 of 33 (21%) were found to have IIR during the redo procedure. Conclusions: (1) Electrogram and ECG patterns of IIR frequently show atypical flutter. (2) IIR was successfully ablated in an area of the CTI associated with maximal duration of FPs. (3) IIR is a significant cause of 'recurrent flutter' in patients with prior CTI ablation. (J Cardiovasc Electrophysiol, Vol. 21, pp. 1099-1106) [ABSTRACT FROM AUTHOR]

Background: Remote magnetic catheter navigation (RCN) is gaining acceptance in clinical cardiac electrophysiology, but details regarding how RCN affects procedure execution are not well characterized. Methods: From January 1, 2005, to November 30, 2007, 721 cases were retrospectively analyzed and compared. Of these, 127 used RCN and 594 used manual catheter navigation (MCN). Data including procedure time, fluoroscopy time, ablation catheter, procedural success, and complications were extracted from our procedure database and compared between RCN and MCN. Results: RCN use significantly decreased fluoroscopy time for atrial fibrillation (AF) ablation (−29 minutes, P < 0.001), atrioventricular nodal reentrant tachycardia ablation (−14 minutes, P < 0.001), and atrioventricular reentrant tachycardia ablation (−18 minutes, P = 0.045). While RCN significantly increased mean procedure time for AF (+36 minutes, P = 0.003) and atypical atrial flutter cases (+116 minutes, P = 0.016), RCN AF procedure time diminished with increasing number of cases performed. Two cases of tamponade occurred during AF ablation using MCN (2.2%, 2 of 91 cases). No tamponade occurred during all 75 AF ablations with RCN. Conclusion: RCN can reduce fluoroscopy time and may reduce complications during catheter ablation. While it may increase total procedure duration, procedure times decrease with increasing operator experience. [ABSTRACT FROM AUTHOR]

Background: Atrial fibrillation (AF) has been linked to an inflammatory process detected through various biomarkers, including C-Reactive Protein (CRP). Early recurrence of AF within the first 3 months after curative AF ablation is not felt to reflect success or failure of the procedure. We hypothesized that this early recurrence is due to an inflammatory response to the ablation itself. We therefore sought to evaluate levels of CRP after AF ablation. Methods: We prospectively enrolled subjects undergoing AF ablation. A control group of patients undergoing ablation for supraventricular tachycardia (SVT) was also enrolled. Each patient had CRP drawn on the day of the procedure (prior to ablation) and during their first follow-up (median 49 days, interquartile range [IQR] 37–93) and second follow-up (median 147 days, IQR 141–257) clinic visits. Patient interviews were performed and medical histories reviewed for evidence of recurrent AF prior to the first follow-up. Results: CRP levels significantly increased from baseline to first follow-up in the AF ablation group (P = 0.0017). CRP did not significantly change after SVT ablation (P = 0.92). Seventeen (45%) of the AF subjects exhibited recurrence of AF prior to first follow-up. After adjusting for multiple potential confounders, AF ablation patients with recurrent AF prior to their first follow-up had a statistically significant greater odds of having an increase in CRP (OR 21, 95% CI 1.1–417, P = 0.045). Conclusions: AF ablation generates an inflammatory response that persists for several weeks. This inflammation may explain early recurrence of AF after curative ablation. [ABSTRACT FROM AUTHOR]

Background: Although evidence suggests that alcohol is associated with atrial fibrillation (AF), the association between alcohol and atrial flutter (AFL) has not been examined. The mechanism connecting alcohol and atrial arrhythmias is unknown. Methods: Alcohol intake was determined in 195 consecutive patients with AF and AFL. Control subjects included patients with other supraventricular arrhythmias (n = 132) and healthy subjects (n = 54). Because of important competing risk factors for atrial arrhythmias in the elderly, stratification by age was performed. In a subset, atrial effective refractory periods (AERPs) were obtained from the high right atrium and proximal and distal coronary sinus. Results: AF and AFL patients were significantly more likely to be daily alcohol drinkers (27% vs 14% of controls, P = 0.001). In multivariable analysis, AFL patients ≤ 60 years of age were significantly more likely to be daily drinkers than to drink no alcohol compared to controls (odds ratio 17, 95% confidence interval 1.6–192.0, P = 0.019). Progressively more frequent alcohol intake was significantly associated with a progressively greater odds of AFL in patients ≤ 60 years of age (P = 0.045). Neither AF subjects of any age nor AFL subjects > 60 years of age exhibited significant associations with alcohol after multivariable adjustment. Right AERPs shortened significantly with increasing amounts of alcohol intake (P = 0.025), whereas left AERPs were not associated with alcohol intake. Conclusions: Alcohol intake is positively associated with AFL in younger patients. The mechanism may be related to a shortening of the right AERP. [ABSTRACT FROM AUTHOR]

Background: Systolic time intervals measured by echocardiography and carotid artery tracings are validated methods of assessing left ventricular function. However, the clinical utility of phonoelectrocardiographic systolic time intervals for predicting heart failure using newer technology has not been evaluated.Methods: We enrolled 100 adult patients undergoing left heart catheterization. Participants underwent computerized phonoelectrocardiographic analysis, left ventricular end-diastolic pressure (LVEDP) measurement, transthoracic echocardiographic measurement of left ventricular ejection fraction (LVEF), and B-type natriuretic peptide (BNP) testing. The heart rate-adjusted systolic time intervals included the time from the Q wave onset to peak S1 (electromechanical activation time, EMAT), Q wave onset to peak S2 (electromechanical systole, Q-S2), and peak S1 to peak S2 (left ventricular systolic time, LVST). Left ventricular dysfunction was defined as the presence of both LVEDP >15 mmHg and LVEF <50%.Results: EMAT (r =-0.51; P < 0.0001), EMAT/LVST (r =-0.41; P = 0.0001), and Q-S2 (r =-0.39; P = 0.0003) correlated with LVEF, but not with LVEDP. An abnormal EMAT > or =15 (odds ratio 1.38, P < 0.0001) and EMAT/LVST > or =0.40 (OR 1.13, P = 0.002) were associated with left ventricular dysfunction. EMAT > or =15 had 44% sensitivity, 94% specificity, and a 7.0 likelihood ratio for left ventricular dysfunction, while EMAT/LVST > or =0.40 had 55% sensitivity, 95% specificity, and a 11.7 likelihood ratio. In patients with an intermediate BNP (100-500 pg/mL), the likelihood ratio increased from 1.1 using the BNP result alone to 11.0 when adding a positive EMAT test for predicting left ventricular dysfunction.Conclusions: Phonoelectrocardiographic measures of systolic time intervals are insensitive but highly specific tests for detecting abnormalities in objective markers of left ventricular function. EMAT and EMAT/LVST provide diagnostic information independent of BNP for detecting patients with left ventricular dysfunction. [ABSTRACT FROM AUTHOR]

Introduction: A substantial number of patients require a second left atrial procedure after ablation for atrial fibrillation (AF), either for left atrial flutter or recurrent AF. The success and complication rates of repeat transseptal catheterization in these patients are unknown. The aim of this study was to determine the difficulty and/or success rates of repeat transseptal catheterization after left atrial ablation for AF. Methods and Results: Consecutive patients undergoing repeat left atrial procedures after ablation for AF over a 1-year period were enrolled. Difficulties with, success rates, and complications of the first and second transseptal catheterizations were recorded. Sixteen patients underwent a repeat transseptal catheterization. Of the 4 in whom the first procedure was performed with an ablation catheter across a patent foramen ovale (PFO), 3 required a transseptal puncture for their repeat procedure. The remaining 12 underwent transseptal puncture without difficulty for their first procedure, and, despite the same operators for each patient, the repeat transseptal was noted to be difficult in 5. Of those 5, the transseptal puncture was unsuccessful due to increased interatrial septal thickness in 2 patients. One repeat transseptal attempt was aborted after posterior right atrial puncture with the transseptal needle occurred, attributed to distorted interatrial septal anatomy not observed prior to the first case. Conclusions: Compared with the first procedure, repeat transseptal catheterization after ablation for AF, whether initially performed across a PFO or via a transseptal puncture, is more difficult, less often successful, and potentially associated with more complications. [ABSTRACT FROM AUTHOR]

Background: Cardiovascular risk factors (CVRFs) are linked to cognitive aging. Most studies rely on lengthy in‐person assessments, and it is unclear if web‐based platforms can be used to detect the contribution of risk factors, including CVRFs, to cognitive aging offering a more pragmatic and low cost approach. Method: We recruited 239 adults who were enrolled in the Health eHeart project in order to conduct the Brain eHealth study, a mobile health feasibility study of web‐based measurement tools in adults age ≥50. CVRFs were identified based on health surveys from the Health eHeart study using the Eureka Research platform between March 2013, and February 2019, and included hypertension, high cholesterol, diabetes, and atrial fibrillation. After an average of 3 years participants completed a web‐based cognitive assessment with the BrainHQ platform (POSIT Science) that assessed 3 cognitive domains: episodic memory, working memory, and executive function. We used linear regression models to examine the association between CVRFs and cognitive function. Result: Among the 239 participants (mean age, 62.7±8.8, 43% female, 89% white), CVRF prevalence was 54% for high cholesterol, 44% for hypertension, 12% for atrial fibrillation, and 7% for diabetes. In multivariable models adjusted for age, race/ethnicity, and sex, atrial fibrillation was associated with poor working memory (β = ‐0.52, 95%CI ‐0.92,‐0.11) and worse episodic memory (β = ‐0.26, 95%CI ‐0.42,‐0.08), and hypertension was associated with worse episodic memory (β = ‐0.25, 95%CI ‐0.42, ‐0.08). There was no association for diabetes or high cholesterol. In a sensitivity analysis, we further adjusted for motor speed processing, which led to similar results. Conclusion: Results of this feasibility study suggest that web‐based tools may be used to detect the contribution of CVRFs, especially atrial fibrillation and hypertension to cognitive function in older adults. The potential of these mobile measurement tools to track the relationship between older adults' cardiovascular health and cognitive aging should be further investigated in a larger study. [ABSTRACT FROM AUTHOR]

The article presents a case study of a 63-year-old woman with a history of palpitations and documented narrow complex tachycardia who was referred for electrophysiology study. The result of the electrocardiogram (ECG) showed a long RP tachycardia with A-V relationship and superiorly directed p-wave. Pseudo A-A-V response was suspected due to the ventricular overdrive pacing from the right ventricular apex.

On the cover: The cover image, by Judit Szilágyi et al., is based on the Original Article Atrial fibrillation patients with isolated pulmonary veins: Is sinus rhythm achievable?, DOI: 10.1111/jce.13230. [ABSTRACT FROM AUTHOR]

A letter to the editor is presented in response to the article "Predictors of Axillary Vein Location for Vascular Access During Pacemaker and Defibrillator Lead Implantation" by J. C. Hsu et al.

The article focuses on understanding the etiology of arrhythmias by examining the association between inflammation and arrhythmias in human subjects. Using simultaneous, multisite epicardial mapping, the investigators found that a line of conduction block between the vena cavae, otherwise found to be necessary for the development of atrial flutter (AFL).

Background: With adoption of telemedicine, physicians are increasingly asked to diagnose ST-segment elevation myocardial infarctions (STEMIs) based on electrocardiograms (ECGs) with minimal associated clinical information. We sought to determine physicians' diagnostic agreement and accuracy when interpreting potential STEMI ECGs., Methods and Results: A cross-sectional survey was performed consisting of 36 deidentified ECGs that had previously resulted in putative STEMI diagnoses. Emergency physicians, cardiologists, and interventional cardiologists participated in the survey. For each ECG, physicians were asked, "based on the ECG above, is there a blocked coronary artery present causing a STEMI?" The reference standard for ascertaining the STEMI diagnosis was subsequent emergent coronary arteriography. Responses were analyzed with generalized estimating equations to account for nested and repeated measures. One hundred twenty-four physicians interpreted a total of 4392 ECGs. Among all physicians, interreader agreement (kappa) for ECG interpretation was 0.33, reflecting poor agreement. The sensitivity to identify "true" STEMIs was 65% (95% CI: 63 to 67) and the specificity was 79% (95% CI: 77 to 81). There was a 6% increase in the odds of accurate ECG interpretation for every 5 years of experience since medical school graduation (OR 1.06, 95% CI: 1.02 to 1.10, P = 0.01). After adjusting for experience, there was no significant difference in the odds of accurate interpretation by specialty-Emergency Medicine (reference), General Cardiology (AOR 0.97, 95% CI: 0.79 to 1.2, P = 0.80), or Interventional Cardiology physicians (AOR 1.24, 95% CI: 0.93 to 1.7, P = 0.15)., Conclusions: There is significant physician disagreement in interpreting ECGs with features concerning for STEMI. Such ECGs lack the necessary sensitivity and specificity to act as a suitable "stand-alone" diagnostic test.