Combined pulsed field ablation with ultra-low temperature cryoablation: A preclinical experience.

BACKGROUND: Combining pulsed field ablation (PFA) with ultra-low temperature cryoablation (ULTC) represents a novel energy source which may create more transmural cardiac lesions. We sought to assess the feasibility of lesions created by combined cryoablation and pulsed field ablation (PFCA) versus PFA alone. METHODS: Ablations were performed using a custom PFA generator, ULTC console, and an ablation catheter with insertable stylets. PFA was delivered in a biphasic, bipolar train. PFCA precooled the tissue for 30 s followed by a concurrent PFA train. Benchtop testing using Schlieren imaging and microbubble volume assessment were used to compare PFA and PFCA. PFA and PFCA lesions using pre-optimized and optimized ablation protocols were studied in 6 swine. Pre and post-ECGs were recorded for each ablation and a gross necropsy was performed at 14 days. RESULTS: Consistent with benchtop comparisons of heat and microbubble generation, PFA deliveries in the animals were accompanied by muscle contractions and significant microbubbles (Grade 2-3) visible on intracardiac echo while neither occurred during PFCA at higher voltage levels. Both PFA and PFCA acutely eliminated or highly attenuated (>80%) local atrial electrograms. Histology of PFA and PFCA lesions indicated depth up to 6-7 mm and nearly all lesions were transmural. Optimized PFCA produced wider cavotricuspid isthmus lesions with evidence of tissue selectivity. CONCLUSION: A novel technology combining PFA and ULTC into one energy source demonstrated in-vivo feasibility for PFCA ablation. PFCA had a more favorable thermal profile and did not produce muscle contraction or microbubbles while extending lesion depth beyond cryoablation.

Cannabis, cocaine, methamphetamine, and opiates increase the risk of incident atrial fibrillation.

AIMS: Atrial fibrillation (AF) is now regarded as a preventable disease, requiring a search for modifiable risk factors. With legalization of cannabis and more lenient laws regarding the use of other illicit substances, investigation into the potential effects of methamphetamine, cocaine, opiate, and cannabis exposure on incident AF is needed. METHODS AND RESULTS: Using Office of Statewide Health Planning and Development databases, a longitudinal analysis was performed of adult Californians ≥18 years of age who received care in an emergency department, outpatient surgery facility, or hospital from 1 January 2005 to 31 December 2015. Associations between healthcare coding for the use of each substance and a new AF diagnosis were assessed. Among 23,561,884 patients, 98 271 used methamphetamine, 48 701 used cocaine, 10 032 used opiates, and 132 834 used cannabis. Of the total population, 998 747 patients (4.2%) developed incident AF during the study period. After adjusting for potential confounders and mediators, use of methamphetamines, cocaine, opiates, and cannabis was each associated with increased incidence of AF: hazard ratios 1.86 [95% confidence interval (CI) 1.81-1.92], 1.61 (95% CI 1.55-1.68), 1.74 (95% CI 1.62-1.87), and 1.35 (95% CI 1.30-1.40), respectively. Negative control analyses in the same cohort failed to reveal similarly consistent positive relationships. CONCLUSION: Methamphetamine, cocaine, opiate, and cannabis uses were each associated with increased risk of developing incident AF. Efforts to mitigate the use of these substances may represent a novel approach to AF prevention.

Transvenous management of cardiac implantable electronic device late lead perforation.

INTRODUCTION: Late lead perforation (LLP), defined as perforation ≥30 days from cardiac implantable electronic device implant, is a rare diagnosis and little data exist regarding management practices and outcomes. The purpose of this study was to evaluate the occurrence, safety, and efficacy of transvenous management of clinically significant LLP. METHODS: The electronic medical records of a single-center tertiary hospital were reviewed for all patients who were referred for LLP or its sequelae. RESULTS: Eleven consecutive patients were identified from October 2011 to December 2018 with clinically significant LLP. Patients most often presented with pericardial symptoms with the exception of one asymptomatic patient. The median time from lead implant to intervention for LLP was 246 days. Nine patients were managed with an initial transvenous approach, with one requiring sternotomy (lead 6.3 years old). Two patients had a surgical approach, one performed at an outside hospital with subsequent death and another had a mini-thoracotomy, but the lead was removed percutaneously with no surgical repair. In this small cohort, there was no association between the lead extending beyond the parietal pericardium and surgical repair (P = .99). CONCLUSION: Our single-center experience suggests that LLP can be initially managed with a cautious transvenous approach in most patients, but intraprocedural ultrasound for pericardial monitoring and a rescue plan with immediate surgical back up is mandatory.

Atrial arrhythmias in heart failure with a reduced ejection fraction.

PURPOSE OF REVIEW: Atrial arrhythmias are common among individuals with heart failure with a reduced ejection fraction (HFrEF). This review describes management options for these arrhythmias and discusses emerging clinical data supporting catheter ablation. RECENT FINDINGS: Several recent clinical trials indicate that catheter ablation is superior to pharmacologic therapy for management of symptomatic atrial fibrillation in the setting of HFrEF. Restoration and maintenance of sinus rhythm appears to have the greatest benefit with regard to ejection fraction improvement among individuals with a nonischemic heart failure etiology and minimal left ventricular fibrosis. SUMMARY: A rhythm control strategy should be strongly considered in patients with HFrEF, especially when the atrial arrhythmia is symptomatic or is present at the time of a heart failure diagnosis. Catheter ablation may be the preferred strategy for maintenance of sinus rhythm in this patient population.

Electromagnetic Interference with Protocolized Electrosurgery Dispersive Electrode Positioning in Patients with Implantable Cardioverter Defibrillators.

WHAT WE ALREADY KNOW ABOUT THIS TOPIC: Electromagnetic interference from monopolar electrosurgery may disrupt implantable cardioverter defibrillators.Current management recommendations by the American Society of Anesthesiologists and Heart Rhythm Society are based on expert clinical opinion since there is a paucity of data regarding the risk of electromagnetic interference to implantable cardioverter defibrillators during surgery. WHAT THIS ARTICLE TELLS US THAT IS NEW: With protocolized electrosurgery dispersive electrode positioning in patients with implantable cardioverter defibrillators, the risk of clinically meaningful electromagnetic interference was 7% in above-the-umbilicus noncardiac surgery and 0% in below-the-umbilicus surgery. In cardiac surgery, clinically meaningful electromagnetic interference with use of an underbody dispersive electrode was 29%.Despite protocolized dispersive electrode positioning, the risk of electromagnetic interference in above-the-umbilicus surgery is high, supporting recommendations to suspend antitachycardia therapy when monopolar electrosurgery is used above the umbilicus.With protocolized dispersive electrode positioning, the risk of electromagnetic interference in below-the-umbilicus surgery is negligible, implying that suspending antitachycardia therapy might be unnecessary in these cases.With an underbody dispersive electrode, the risk of electromagnetic interference in cardiac surgery is high. BACKGROUND: The goal of this study was to determine the occurrence of intraoperative electromagnetic interference from monopolar electrosurgery in patients with an implantable cardioverter defibrillator undergoing surgery. A protocolized approach was used to position the dispersive electrode. METHODS: This was a prospective cohort study including 144 patients with implantable cardioverter defibrillators undergoing surgery between May 2012 and September 2016 at an academic medical center. The primary objectives were to determine the occurrences of electromagnetic interference and clinically meaningful electromagnetic interference (interference that would have resulted in delivery of inappropriate antitachycardia therapy had the antitachycardia therapy not been programmed off) in noncardiac surgeries above the umbilicus, noncardiac surgeries at or below the umbilicus, and cardiac surgeries with the use of an underbody dispersive electrode. RESULTS: The risks of electromagnetic interference and clinically meaningful electromagnetic interference were 14 of 70 (20%) and 5 of 70 (7%) in above-the-umbilicus surgery, 1 of 40 (2.5%) and 0 of 40 (0%) in below-the-umbilicus surgery, and 23 of 34 (68%) and 10 of 34 (29%) in cardiac surgery. Had conservative programming strategies intended to reduce the risk of inappropriate antitachycardia therapy been employed, the occurrence of clinically meaningful electromagnetic interference would have been 2 of 70 (2.9%) in above-the-umbilicus surgery and 3 of 34 (8.8%) in cardiac surgery. CONCLUSIONS: Despite protocolized dispersive electrode positioning, the risks of electromagnetic interference and clinically meaningful electromagnetic interference with surgery above the umbilicus were high, supporting published recommendations to suspend antitachycardia therapy whenever monopolar electrosurgery is used above the umbilicus. For surgery below the umbilicus, these risks were negligible, implying that suspending antitachycardia therapy is likely unnecessary in these patients. For cardiac surgery, the risks of electromagnetic interference and clinically meaningful electromagnetic interference with an underbody dispersive electrode were high. Conservative programming strategies would not have eliminated the risk of clinically meaningful electromagnetic interference in either noncardiac surgery above the umbilicus or cardiac surgery.

Predictors of atrial ectopy and their relationship to atrial fibrillation risk.

AIMS: Premature atrial contractions (PACs) are known to trigger and predict atrial fibrillation (AF). We sought to identify the determinants of PACs and the degree to which PACs mediate the effects of established risk factors for AF. METHODS AND RESULTS: Predictors of baseline PAC frequency were examined using a Holter Study among 1392 participants in the Cardiovascular Health Study, a community-based cohort of individuals aged ≥65 years. Participants were then followed for their first diagnosis of AF. Independent predictors of PACs were identified, and the extent to which PACs might mediate the relationship between those predictors and AF was determined. The median hourly frequency of PACs was 2.7 (interquartile range 0.8-12.1). After multivariable adjustment, increasing age, increasing height, decreasing body mass index, and a history of myocardial infarction were each associated with more PACs. Regarding modifiable predictors, participants using beta-blockers had 21% less [95% confidence interval (95% CI) 9-30%, P = 0.001] and those performing at least moderate intensity exercise vs. lower intensity exercisers had 10% less (95% CI 1-18%, P = 0.03) PACs. Higher PAC frequency explained 34% (95% CI 22-57%, P < 0.0001) of the relationship between increasing age and AF risk and 27% (95% CI 10-75%, P = 0.004) of the relationship between taller height and AF risk. CONCLUSION: Enhancing physical activity and use of beta-blockers may represent fruitful strategies to mitigate PAC frequency. A substantial proportion of the excess risk of AF due to increasing age and taller height may be explained by an increase in PAC frequency.

Impact of genetic variants on the upstream efficacy of renin-angiotensin system inhibitors for the prevention of atrial fibrillation.

BACKGROUND: Renin-angiotensin system (RAS) inhibition via angiotensin-converting enzyme inhibitors and angiotensin II receptor blockers may reduce the risk of developing atrial fibrillation (AF) in certain populations, but the evidence is conflicting. Recent genome-wide association studies have identified several single nucleotide polymorphisms (SNPs) associated with AF, potentially identifying clinically relevant subtypes of the disease. We sought to investigate the impact of carrier status of 9 AF-associated SNPs on the efficacy of RAS inhibition for the primary prevention of AF. METHODS: We performed SNP-RAS inhibitor interaction testing with unadjusted and adjusted Cox proportional hazards models using a discovery (Cardiovascular Health Study) and a replication (Atherosclerosis Risk in Communities) cohort. Additive genetic models were used for the SNP analyses, and 2-tailed P values <.05 were considered statistically significant. RESULTS: Among 2,796 Cardiovascular Health Study participants, none of the 9 a priori identified candidate SNPs exhibited a significant SNP-drug interaction. Two of the 9 SNPs, rs2106261 (16q22) and rs6666258 (1q21), revealed interaction relationships that neared statistical significance (with point estimates in the same direction for angiotensin-converting enzyme inhibitor only and angiotensin II receptor blocker only analyses), but neither association could be replicated among 8,604 participants in Atherosclerosis Risk in Communities. CONCLUSIONS: Our study failed to identify AF-associated SNP genetic subtypes of AF that derive increased benefit from upstream RAS inhibition for AF prevention. Future studies should continue to investigate the impact of genotype on the response to AF treatment strategies in an effort to develop personalized approaches to therapy and prevention.

Atrial Fibrillation Associated Genetic Variants and Left Atrial Histology: Evaluation for Molecular Sub-Phenotypes.

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 (ß-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.

Atrial Fibrillation Predictors: Importance of the Electrocardiogram.

Atrial fibrillation (AF) is the most common arrhythmia in adults and is associated with significant morbidity and mortality. Substantial interest has developed in the primary prevention of AF, and thus the identification of individuals at risk for developing AF. The electrocardiogram (ECG) provides a wealth of information, which is of value in predicting incident AF. The PR interval and P wave indices (including P wave duration, P wave terminal force, P wave axis, and other measures of P wave morphology) are discussed with regard to their ability to predict and characterize AF risk in the general population. The predictive value of the QT interval, ECG criteria for left ventricular hypertrophy, and findings of atrial and ventricular ectopy are also discussed. Efforts are underway to develop models that predict AF incidence in the general population; however, at present, little information from the ECG is included in these models. The ECG provides a great deal of information on AF risk and has the potential to contribute substantially to AF risk estimation, but more research is needed.

Procedure timing as a predictor of inhospital adverse outcomes from implantable cardioverter-defibrillator implantation: insights from the National Cardiovascular Data Registry.

BACKGROUND: Implantable cardioverter-defibrillator (ICD) procedures performed later in the day and on weekends/holidays may be associated with adverse events due to a variety of factors including operator fatigue, handoffs, reduced staffing, and limited resource availability. We sought to determine whether patients implanted with ICDs in the afternoon/evening and on weekends/holidays are at increased risk for adverse events. METHODS: We studied 148,004 first-time ICD recipients in the National Cardiovascular Data Registry-ICD Registry implanted between April 2010 and March 2012. Using hierarchical multivariable logistic regression adjusting for patient, implanting physician, and hospital characteristics, we examined the association between both ICD implant start time and day of week with any complication, a prolonged hospital stay, and mortality. RESULTS: Most ICD implants (52.6%; n = 77,853) were performed in the morning (6 am-12 pm) and during the regular workweek (97.5%; n = 144,266). After multivariable adjustment, ICD recipients implanted in the afternoon (12 pm-5 pm)/evening (5 pm-6 am) compared with the morning experienced a greater odds of any complication (odds ratio [OR] 1.08; 95% CI 1.01-1.15; P = .0168), hospital stay >1 day (OR 1.29; 95% CI 1.25-1.33; P < .0001) but not inhospital death (OR 1.06; 95% CI 0.88-1.27; P = .5322). Implantable cardioverter-defibrillator recipients implanted on weekend/holidays compared with the mid-workweek also experienced a significantly greater odds of hospital stay >1 day (OR 1.40; 95% CI 1.29-1.53; P < .0001), no statistically significant differences in total complications (OR 1.14; 95% CI 0.96-1.36; P = .1371), and a trend toward more inhospital death (OR 1.52; 95% CI 0.98-2.38; P = .0642). CONCLUSIONS: In a large, real-world population, ICD recipients implanted in the afternoon/evening and on weekends/holidays more often experienced adverse events, particularly prolonged hospital stays.

Sequential Percutaneous LAA Ligation and Pulmonary Vein Isolation in Patients with Persistent AF: Initial Results of a Feasibility Study.

INTRODUCTION: Left atrial appendage (LAA) ligation results in LAA electrical isolation and a decrease in atrial fibrillation (AF) burden. This study assessed the feasibility of combined percutaneous LAA ligation and pulmonary vein isolation (PVI) in patients with persistent AF. METHODS AND RESULTS: A total of 22 patients with persistent AF underwent LAA ligation with the LARIAT device followed by PVI. PVI was confirmed with the demonstration of both entrance and exit block. Patients (n = 10) in sinus rhythm pre- and post-LAA ligation underwent P-wave analysis. Monitoring for AF was performed at 1, 3, and 6 months postablation. LAA ligation was successful in 21 of 22 (95%) patients. The procedure was aborted in one patient due to pericardial adhesions. PVI was performed in 20 of 21 patients. One patient converted to atrial flutter with a controlled ventricular response after LAA ligation and refused subsequent PVI. Demonstration of entrance and exit block was achieved in 19 of 20 patients. At 3 months, 13 of 19 (68.4%) patients were in sinus rhythm. Four patients underwent a second PVI. At 6 months, 15 of 20 (75%) patients were in sinus rhythm. There was a significant decrease in P-wave duration and P-wave dispersion after LAA ligation. Complications with LAA ligation included pericarditis, a delayed pleural effusion, and a late pericardial effusion. CONCLUSIONS: Staged LAA ligation and PVI is feasible and decreases P-wave dispersion. Randomized studies are needed to assess the efficacy of LAA ligation as adjunctive therapy to PVI for maintaining sinus rhythm in patients with persistent AF.

Incident atrial fibrillation among Asians, Hispanics, blacks, and whites.

BACKGROUND: Because the association between atrial fibrillation (AF) and race has only been rigorously compared in population-based studies that dichotomized participants as white or black, it is unclear whether white race confers elevated AF risk or black race affords AF protection. METHODS AND RESULTS: The Healthcare Cost and Utilization Project was used to identify patients receiving hospital-based care in California between January 1, 2005 and December 31, 2009. The association between race and incident AF was examined using Cox proportional hazards models. Interaction analyses were performed to elucidate the mechanism underlying the race-AF association. Among 13 967 949 patients, 375 318 incident AF episodes were observed over a median 3.2 (interquartile range 1.8-4.3) years. In multivariable Cox models adjusting for patient demographics and established AF risk factors, blacks (hazard ratio, 0.84; 95% confidence interval, 0.82-0.85; P<0.001), Hispanics (hazard ratio, 0.78; 95% confidence interval, 0.77-0.79; P<0.001), and Asians (hazard ratio, 0.78; 95% confidence interval, 0.77-0.79; P<0.001) each exhibited a lower AF risk compared with whites. AF risk among whites was disproportionately higher in the absence of acquired cardiovascular risk factors and diminished or reversed in the presence of comorbid diseases. Although Hispanics and Asians also had a lower adjusted risk of incident atrial flutter compared with whites, the risk of flutter was significantly higher among blacks. CONCLUSIONS: In a large hospital-based cohort, whites have an increased risk of AF whether compared with blacks, Asians, or Hispanics. The heightened AF risk among whites is most pronounced in the absence of cardiovascular comorbidities.

Atrial ectopy as a predictor of incident atrial fibrillation: a cohort study.

BACKGROUND: Atrial fibrillation (AF) prediction models have unclear clinical utility given the absence of AF prevention therapies and the immutability of many risk factors. Premature atrial contractions (PACs) play a critical role in AF pathogenesis and may be modifiable. OBJECTIVE: To investigate whether PAC count improves model performance for AF risk. DESIGN: Prospective cohort study. SETTING: 4 U.S. communities. PATIENTS: A random subset of 1260 adults without prevalent AF enrolled in the Cardiovascular Health Study between 1989 and 1990. MEASUREMENTS: The PAC count was quantified by 24-hour electrocardiography. Participants were followed for the diagnosis of incident AF or death. The Framingham AF risk algorithm was used as the comparator prediction model. RESULTS: In adjusted analyses, doubling the hourly PAC count was associated with a significant increase in AF risk (hazard ratio, 1.17 [95% CI, 1.13 to 1.22]; P < 0.001) and overall mortality (hazard ratio, 1.06 [CI, 1.03 to 1.09]; P < 0.001). Compared with the Framingham model, PAC count alone resulted in similar AF risk discrimination at 5 and 10 years of follow-up and superior risk discrimination at 15 years. The addition of PAC count to the Framingham model resulted in significant 10-year AF risk discrimination improvement (c-statistic, 0.65 vs. 0.72; P < 0.001), net reclassification improvement (23.2% [CI, 12.8% to 33.6%]; P < 0.001), and integrated discrimination improvement (5.6% [CI, 4.2% to 7.0%]; P < 0.001). The specificity for predicting AF at 15 years exceeded 90% for PAC counts more than 32 beats/h. LIMITATION: This study does not establish a causal link between PACs and AF. CONCLUSION: The addition of PAC count to a validated AF risk algorithm provides superior AF risk discrimination and significantly improves risk reclassification. Further study is needed to determine whether PAC modification can prospectively reduce AF risk. PRIMARY FUNDING SOURCE: American Heart Association, Joseph Drown Foundation, and National Institutes of Health.

Contemporary trends in incident ischemic stroke, intracranial hemorrhage, and mortality in individuals with atrial fibrillation.

BACKGROUND: The prognosis for atrial fibrillation (AF) patients is based on data that is decades old. Given evolving standards of clinical practice, we sought to evaluate temporal trends in clinically important outcomes among patients with AF. METHODS: California's Department of Health Care Access and Information databases were used to identify adults aged ≥ 18 years with AF receiving hospital-based care in California. We compared 3 time-periods: 2005-2009, 2010-2014, and 2015-2019. ICD codes were used to identify chronic diseases and acute events. The outcomes were incident ischemic stroke, intracranial hemorrhage, and overall mortality. RESULTS: We included 2 009 832 patients with AF (52.7% males, 70.7% Whites, and mean age of 75.0 years), divided in 3 cohorts: 2005-2009 (n = 738 954), 2010-2014 (n = 609 447), and 2015-2019 (n = 661 431). Each outcome became substantially less common with time: compared to 2005-2009, AF patients diagnosed in 2015-2019 experienced a 34% (adjusted hazard ratio [HR] 0.66, 95% CI 0.64-0.69), 22% (HR 0.78, 0.75-0.82), and 24% (HR 0.76, 0.75-0.77) reduction in risk of incident ischemic stroke, intracranial hemorrhage, and mortality, respectively. Between 2005-2009 and 2015-2019, patients aged ≥ 65 years experienced more reductions in each outcome compared to younger patients (p < 0.001 for all), and declines in each outcome were significantly lower for Hispanics and Blacks compared to white patients. CONCLUSION: The risks of stroke, intracranial hemorrhage, and death have significantly declined among AF patients, although differences in the magnitude of improvement of these outcomes by demographic groups were observed. Commonly described estimates of the prognosis for AF patients should be updated to reflect contemporary care.

Minimum National Prevalence of Diagnosed Atrial Fibrillation Inferred From California Acute Care Facilities.

BACKGROUND: Prevalence estimates of atrial fibrillation (AF) from large populations have not been updated for >2 decades. Using data from 1996 to 1997, a previous study projected that there would be 3.3 million adults with AF in the United States in 2020. OBJECTIVES: The purpose of this study was to determine the contemporary age-, sex-, and race-standardized prevalence and the number of adults with diagnosed AF in the United States. METHODS: We merged California's state-wide health care databases to assemble a cohort of adults aged ≥20 years who received hospital-based care in California from 2005 to 2019. International Classification of Diseases codes were used to identify AF and other comorbidities. After accounting for deaths, we utilized the U.S. Census to calculate the national age-, sex-, and race-standardized estimates of diagnosed AF. RESULTS: Of 29,250,310 patients (mean age 50.6 ± 19.8 years, 53.8% women, 50.1% White), 2,003,867 (6.8%) had an AF diagnosis. The proportion of patients with diagnosed AF increased from 4.49% in 2005 to 2009 to 6.82% in 2015 to 2019. Over time, AF patients became relatively younger, were less likely to be female or White, and were more likely to have hypertension and diabetes. Standardizing based on age-, sex-, race-, and ethnicity-based proportions to the U.S. population, we estimate that the current national prevalence of diagnosed AF is at least 10.55 million (95% CI: 10.48-10.62 million), comprising 4.48% (95% CI: 4.47%-4.49%) of the adult population. CONCLUSIONS: The prevalence of diagnosed AF in the United States is higher than previously estimated. More efficient prevention and treatment strategies are needed to curb the burden of AF in the United States.

Atrial Flutter and Sick Sinus Syndrome.

BACKGROUND: Sick sinus syndrome (SSS) is a common condition resulting in reduced quality of life, syncope, and pacemaker (PPM) implantation, but predictors have not been elucidated. While atrial arrhythmias are frequently associated with SSS, we hypothesized that atrial flutter (AFL) would strongly predict SSS given shared relationships with right atrial, and particularly crista terminalis, fibrosis. OBJECTIVE: To assess the impact of AFL on the occurrence of SSS and associated syncope and PPM implantation. METHODS: Healthcare databases were used to identify adults aged ≥ 18 years receiving hospital-based care in California in 2005-2019. ICD codes were used to identify diagnoses and procedures. Patients were classified based on the presence of AFL and atrial fibrillation (AF). Cox proportional hazard models adjusting for demographics and co-morbidities were employed. RESULTS: We included 29,357,609 individuals (54% females, mean age 46 years), 101,243 with AFL alone, 1,674,680 with AF alone, and 284,547 with AF and AFL. After adjustment for age, sex, race and ethnicity, and co-morbidities, AF, AFL, and both arrhythmias were each associated with increased risk of SSS and associated syncope and PPM implantation (all p<0.001). In the population with AF, an additional AFL diagnosis conferred a higher risk of developing SSS (hazard ratio [HR]1.62, 95% confidence interval [CI] 1.59-1.64), syncope (HR 1.63, 1.54-1.72) and PPM implantation (HR 1.74, 1.70-1.79). CONCLUSION: AFL is associated with an increased risk of incident SSS and its adverse consequences, especially in patients with co-existing AF. AFL may be useful for risk stratification strategies to predict, prevent, and treat SSS.

Systemic infarcts among patients with atrial fibrillation.

BACKGROUND: The epidemiology of atrial fibrillation (AF)-associated thromboembolic complications outside of ischemic strokes has not been thoroughly elucidated. OBJECTIVE: The aim of this study was to describe the epidemiology of AF-associated systemic infarcts and relevant interactions by sex and race/ethnicity. METHODS: Using the Office of Statewide Health Planning and Development, we performed a longitudinal analysis of patients aged ≥18 years who received ambulatory surgery, emergency, or inpatient medical care in California between 2005 and 2015. We determined the distribution of infarct locations and risks of systemic infarcts for patients with AF. Interaction analyses by sex and race/ethnicity were conducted. RESULTS: Of 1,321,694 patients with AF, the average annual rate of systemic infarct was 2.1% ± 0.18% compared with 0.56% ± 0.06% in the 22,944,488 patients without AF. The increased frequency of these infarcts was observed for every body area investigated. After adjustment for potential confounders and mediators, patients with AF experienced a 45% increased risk of a systemic infarct (hazard ratio, 1.45; 95% confidence interval, 1.44-1.47; P < .001). Women, Asians, Blacks, and Hispanics each exhibited a statistically significant heightened relative risk of systemic infarcts in the presence of AF. CONCLUSION: AF increases the risk of infarcts throughout the body. Susceptibility to these systemic infarcts varies by sex and race/ethnicity in patterns similar to differential risks for stroke. The presence of a systemic infarct in the absence of a clear cause should raise suspicion for AF, and the potential benefits of AF prevention and anticoagulation should be considered beyond only infarcts to the brain.

Consideration of patient age and life expectancy in implantable cardioverter-defibrillator referral.

BACKGROUND: Primary prevention implantable cardioverter-defibrillator (ICD) guidelines recommend device consideration for at-risk patients with a life expectancy of greater than 1 year regardless of age. We sought to assess the influence of patient age and prognosis on ICD referral. METHODS: A survey was mailed to a random, national sample of 3,000 physicians in the specialties of cardiology, family medicine, and internal medicine. Participants were asked focused questions regarding patient age, life expectancy, and ICD referral. RESULTS: The overall response rate was 64%. More than one quarter of physicians (n = 386 [27%], 95% CI 25%-30%) withhold primary prevention ICD referral solely because of patient age. Life expectancy is not considered by 23% (n = 324, 95% CI 20%-25%) of physicians before referral, whereas 13% (n = 144, 95% CI 11%-15%) refer patients with a prognosis of less than 1 year. Providers who refer patients for ICD implantation with a life expectancy of less than 1 year are less likely to be cardiologists (odds ratio [OR] 0.50, 95% CI 0.32-0.79, P = .003), are less often affiliated with a teaching hospital (OR 0.62, 95% CI 0.41-0.94, P = .025), and have a greater number of years in practice (OR 1.25 for each 10 years in practice, 95% CI 1.03-1.51, P = .026). Only a minority (n = 315 [22%], 95% CI 20%-24%) of physicians use a life expectancy threshold of 1 year to guide ICD referral. CONCLUSION: Physicians frequently withhold ICD referral because of patient age. The referral of patients with a prognosis of less than 1 year or without consideration of life expectancy is common.