Treatment of Atrial Fibrillation.

IMPORTANCE: Atrial fibrillation is a common arrhythmia that affects more than 2.5 million people in the United States and causes substantial morbidity and mortality, especially regarding the increased risk of stroke. OBJECTIVE: To summarize atrial fibrillation treatment exclusive of stroke prevention. EVIDENCE REVIEW: An Ovid MEDLINE comprehensive literature search was performed on atrial fibrillation therapy excluding anticoagulation and emphasizing studies published within the last 5 years through April 2015 (N = 5044 references). The 2014 atrial fibrillation guideline from the American Heart Association, the American College of Cardiology, and the Heart Rhythm Society also was reviewed. FINDINGS: Reversible causes of atrial fibrillation should be identified. Risk factor modification, including weight loss and treatment of hypertension, diabetes, and obstructive sleep apnea can reduce atrial fibrillation episodes. Appropriate anticoagulation is necessary for patients at substantial stroke risk regardless of rate or rhythm treatment strategy. Sinus rhythm is often needed to control symptoms; however, an alternative strategy for atrial fibrillation is appropriate rate control. Rate control is safe in older patients (those who are about age ≥65 years) followed up for a few years, but no such safety data exist for patients younger than 60 years or for those followed up for longer periods. Thus, selection of therapy is individualized, taking into account present and future medical problems for the patient. Choice of an antiarrhythmic drug is based on safety first vs efficacy. Catheter ablation is an effective nonpharmacological alternative that is often, but not always, the second-line treatment. Reduction of the frequency and duration of atrial fibrillation episodes that result in a significant improvement in quality of life is a good marker of drug treatment success and complete elimination of atrial fibrillation is not required in many patients. Rate control is usually achieved with a ß-blocker or non-dihydropyridine calcium channel blockers. It is important to assess adequate rate control during both rest and activity. If the ventricular rate goes uncontrolled for a prolonged period, tachycardia-mediated cardiomyopathy can occur. CONCLUSIONS AND RELEVANCE: Therapy for atrial fibrillation includes prevention and modification of inciting causes and appropriate anticoagulation. Rate control is necessary for all patients. Maintenance of sinus rhythm with drugs or catheter ablation should be considered based on the individual needs of each patient.

A Multicenter Collaborative Effort to Reduce Preventable Patient Harm Due to Retained Surgical Items.

BACKGROUND: Unintentional retention of surgical items is severe but preventable patient harm in surgical procedures. One multicenter health care organization experienced a harm event due to retained surgical items (RSIs) every eight days in 2019-2020. The research team sought to reduce the incidence of harm due to RSIs, improve near-miss reporting, and increase process reliability in operating rooms across the organization. METHODS: A total of 114 health care facilities in the organization were invited to participate in a multistate, multicenter patient safety initiative to reduce patient harm caused by RSIs. A national-level workgroup comprising various disciplines proposed an evidence-based best practice bundle with five elements: surgical stop, surgical debrief, visual counter, imaging, and reporting of deviations. The workgroup ensured that extensive education and support were accessible to all the participating sites. The researchers monitored the process reliability of bundle elements and improvement milestones of all the sites, along with rates of harm related to RSIs. RESULTS: Implementing the evidence-based RSI reduction bundle across 114 health care facilities resulted in a 14.3% reduction in the rate of harm caused by RSIs and a 59.1% increase in RSI near-miss reporting. The compliance to the RSI bundle reached an average of 70.5%, and 63.2% of the facilities are actively performing Plan-Do-Check-Act (PDCA) cycles to improve bundle compliance continually. CONCLUSION: Implementation of an RSI bundle can be done reliably, can improve near-miss reporting, and can reduce patient harm. Variation in process reliability between centers suggests the significance of overcoming cultural and organizational barriers.

Does the coronavirus disease 2019 (COVID-19) vaccination rate among healthcare personnel reflect their community? An evaluation of a multistate healthcare system.

Coronavirus disease 2019 (COVID-19) vaccination rates of a large health system reflected their respective service areas but varied by work role. Nurse vaccination rates were higher (56.9%) and rates among nursing support personnel were lower (38.6%) than those of their communities (51.7%; P < .001). Physician vaccination rates were highest (71.6%) and were not associated with community vaccination levels.

COVID-19 hospital prevalence as a risk factor for mortality: an observational study of a multistate cohort of 62 hospitals.

BACKGROUND: The associated mortality with COVID-19 has improved compared with the early pandemic period. The effect of hospital COVID-19 patient prevalence on COVID-19 mortality has not been well studied. METHODS: We analysed data for adults with confirmed SARS-CoV-2 infection admitted to 62 hospitals within a multistate health system over 12 months. Mortality was evaluated based on patient demographic and clinical risk factors, COVID-19 hospital prevalence and calendar time period of the admission, using a generalised linear mixed model with site of care as the random effect. RESULTS: 38 104 patients with COVID-19 were hospitalised, and during their encounters, the prevalence of COVID-19 averaged 16% of the total hospitalised population. Between March-April 2020 and January-February 2021, COVID-19 mortality declined from 19% to 12% (p<0.001). In the adjusted multivariable analysis, mid and high COVID-19 inpatient prevalence were associated with a 25% and 41% increase in the odds (absolute contribution to probability of death of 2%-3%) of COVID-19 mortality compared with patients with COVID-19 in facilities with low prevalence (<10%), respectively (high prevalence >25%: adjusted OR (AOR) 1.41, 95% CI 1.23 to 1.61; mid-prevalence (10%-25%): AOR 1.25, 95% CI 1.13 to 1.38). Mid and high COVID-19 prevalence accounted for 76% of patient encounters. CONCLUSIONS: Although inpatient mortality for patients with COVID-19 has sharply declined compared with earlier in the pandemic, higher COVID-19 hospital prevalence remained a common risk factor for COVID-19 mortality. Hospital leaders need to reconsider how we provide support to care for patients in times of increased volume and complexity, such as those experienced during COVID-19 surges.

Coronavirus disease 2019 (COVID-19) pandemic, central-line-associated bloodstream infection (CLABSI), and catheter-associated urinary tract infection (CAUTI): The urgent need to refocus on hardwiring prevention efforts.

BACKGROUND: The coronavirus disease 2019 (COVID-19) pandemic has had a considerable impact on US hospitalizations, affecting processes and patient population. OBJECTIVE: To evaluate the impact of COVID-19 pandemic on central-line-associated bloodstream infections (CLABSIs) and catheter associated urinary tract infections (CAUTIs) in hospitals. METHODS: We performed a retrospective study of CLABSIs and CAUTIs in 78 US 12 months before COVID-19 and 6 months during COVID-19 pandemic. RESULTS: During the 2 study periods, there were 795,022 central-line days and 817,267 urinary catheter days. Compared to the period before the COVID-19 pandemic, CLABSI rates increased by 51.0% during the pandemic period from 0.56 to 0.85 per 1,000 line days (P < .001) and by 62.9% from 1.00 to 1.64 per 10,000 patient days (P < .001). Hospitals with monthly COVID-19 patients representing >10% of admissions had a National Health Safety Network (NHSN) device standardized infection ratio for CLABSI that was 2.38 times higher than hospitals with <5% prevalence during the pandemic period (P = .004). Coagulase-negative Staphylococcus CLABSIs increased by 130% from 0.07 to 0.17 events per 1,000 line days (P < .001), and Candida spp by 56.9% from 0.14 to 0.21 per 1,000 line days (P = .01). In contrast, no significant changes were identified for CAUTI (0.86 vs 0.77 per 1,000 catheter days; P = .19). CONCLUSIONS: The COVID-19 pandemic was associated with substantial increases in CLABSIs but not CAUTIs. Our findings underscore the importance of hardwiring processes for optimal line care and regular feedback on performance to maintain a safe environment.

Comparison of Severe Maternal Morbidities Associated With Delivery During Periods of Circulation of Specific SARS-CoV-2 Variants.

Importance: Infection with SARS-CoV-2, which causes COVID-19, is associated with adverse maternal outcomes. While it is known that severity of COVID-19 varies by viral strain, the extent to which this variation is reflected in adverse maternal outcomes, including nonpulmonary maternal outcomes, is not well characterized. Objective: To evaluate the associations of SARS-CoV-2 infection with severe maternal morbidities (SMM) in pregnant patients delivering during 4 pandemic periods characterized by predominant viral strains. Design, Setting, and Participants: This retrospective cohort study included patients delivering in a multicenter, geographically diverse US health system between March 2020 and January 2022. Individuals with SARS-CoV-2 infection were propensity-matched with as many as 4 individuals without evidence of infection based on demographic and clinical variables during 4 time periods based on the dominant strain of SARS-CoV-2: March to December 2020 (wild type); January to June 2021 (Alpha [B.1.1.7]); July to November 2021 (Delta [B.1.617.2]); and December 2021 to January 2022 (Omicron [B.1.1.529]). Data were analyzed from October 2021 to June 2022. Exposures: Positive SARS-CoV-2 nucleic acid amplification test result during the delivery encounter. Main Outcomes and Measures: The primary outcome was any SMM event, as defined by the US Centers for Disease Control and Prevention, during hospitalization for delivery. Secondary outcomes were number of SMM, respiratory SMM, nonrespiratory SMM, and nontransfusion SMM events. Results: Over all time periods, there were 3129 patients with SARS-CoV-2, with a median (IQR) age of 29.1 (24.6-33.2) years. They were propensity matched with a total of 12 504 patients without SARS-CoV-2, with a median (IQR) age of 29.2 (24.7-33.2) years. Patients with SARS-CoV-2 infection had significantly higher rates of SMM events than those without in all time periods, except during Omicron. While the risk of any SMM associated with SARS-CoV-2 infection was increased for the wild-type strain (odds ratio [OR], 2.74 [95% CI, 1.85-4.03]) and Alpha variant (OR, 2.57 [95% CI, 1.69-4.01]), the risk during the Delta period was higher (OR, 7.69 [95% CI, 5.19-11.54]; P for trend < .001). The findings were similar for respiratory complications, nonrespiratory complications, and nontransfusion outcomes. For example, the risk of nonrespiratory SMM events for patients with vs without SARS-CoV-2 infection were similar for the wild-type strain (OR, 2.16 [95% CI, 1.40-3.27]) and Alpha variant (OR, 1.96 [95% CI, 1.20-3.12]), highest for the Delta variant (OR, 4.65 [95% CI, 2.97-7.29]), and not significantly higher in the Omicron period (OR, 1.21 [95% CI, 0.67-2.08]; P for trend < .001). Conclusions and Relevance: This cohort study found that the SARS-CoV-2 Delta variant was associated with higher rates of SMM events compared with other strains. Given the potential of new strains, these findings underscore the importance of preventive measures.

Effect of Text Message Reminders and Vaccine Reservations on Adherence to a Health System COVID-19 Vaccination Policy: A Randomized Clinical Trial.

Importance: Many organizations implemented COVID-19 vaccination requirements during the pandemic, but the best way to increase adherence to these policies is unknown. Objective: To evaluate if behavioral nudges delivered through text messages could accelerate adherence to a health system's COVID-19 vaccination policy. Design, Setting, and Participants: This randomized clinical trial was conducted within Ascension health system from October 11 to November 8, 2021. Participants included health system employees in the Midwest or South US who were not adherent with the vaccination policy 1 month before its deadline. Data were analyzed from November 17, 2021, to February 25, 2022. Interventions: Participants were randomly assigned to control or to receive a text message intervention that stated a vaccine had been reserved for the participant, with a scheduled date for vaccination within a 2-week period. Participants could reschedule to a different date within the period or upload a copy of their vaccination card. Follow-up text message reminders were sent the day before and the day of the appointment. Main Outcomes and Measures: The primary outcome was adherence to the health system's vaccination policy during the 2-week intervention. Secondary outcomes included time to vaccination during a 4-week follow-up period. Results: The sample included 2000 participants (mean [SD] age, 36.4 [12.3] years; 1724 [86.2%] women), with 1000 participants randomized to the control group and 1000 participants randomized to the intervention group. Overall, there were 164 Hispanic participants (8.2%), 46 non-Hispanic Asian participants (2.3%), 202 non-Hispanic Black participants (10.1%), and 1418 non-Hispanic White participants (70.9%). By the end of the 2-week intervention, 363 participants in the text message nudge group (36.3%) and 318 participants in the control group (31.8%) were adherent with the vaccination policy, representing a significant increase of 4.9 (95% CI, 0.8 to 9.1) percentage points in adjusted analyses comparing the nudge group with the control group (P = .02). Among participants who became adherent by the end of the 4-week follow-up period, the text message nudge significantly reduced time to adherence by a mean of 2.4 (95% CI, 2.1 to 4.7) days (P < .001) and a median of 5.0 (95% CI, 2.5 to 7.7) days (P < .001) compared with the control group. At 4 weeks, overall vaccination adherence was no longer different between groups (control: 477 participants [47.7%]; intervention: 472 participants [47.2%]). Conclusions and Relevance: This randomized clinical trial found that a behavioral nudge delivered through text messages accelerated adherence to a health system's COVID-19 vaccination policy but did change overall adherence by the time of the policy deadline. Trial Registration: ClinicalTrials.gov Identifier: NCT05037201.

Association of Race With Mortality Among Patients Hospitalized With Coronavirus Disease 2019 (COVID-19) at 92 US Hospitals.

IMPORTANCE: While current reports suggest that a disproportionate share of US coronavirus disease 2019 (COVID-19) cases and deaths are among Black residents, little information is available regarding how race is associated with in-hospital mortality. OBJECTIVE: To evaluate the association of race, adjusting for sociodemographic and clinical factors, on all-cause, in-hospital mortality for patients with COVID-19. DESIGN, SETTING, AND PARTICIPANTS: This cohort study included 11 210 adult patients (age ≥18 years) hospitalized with confirmed severe acute respiratory coronavirus 2 (SARS-CoV-2) between February 19, 2020, and May 31, 2020, in 92 hospitals in 12 states: Alabama (6 hospitals), Maryland (1 hospital), Florida (5 hospitals), Illinois (8 hospitals), Indiana (14 hospitals), Kansas (4 hospitals), Michigan (13 hospitals), New York (2 hospitals), Oklahoma (6 hospitals), Tennessee (4 hospitals), Texas (11 hospitals), and Wisconsin (18 hospitals). EXPOSURES: Confirmed SARS-CoV-2 infection by positive result on polymerase chain reaction testing of a nasopharyngeal sample. MAIN OUTCOMES AND MEASURES: Death during hospitalization was examined overall and by race. Race was self-reported and categorized as Black, White, and other or missing. Cox proportional hazards regression with mixed effects was used to evaluate associations between all-cause in-hospital mortality and patient characteristics while accounting for the random effects of hospital on the outcome. RESULTS: Of 11 210 patients with confirmed COVID-19 presenting to hospitals, 4180 (37.3%) were Black patients and 5583 (49.8%) were men. The median (interquartile range) age was 61 (46 to 74) years. Compared with White patients, Black patients were younger (median [interquartile range] age, 66 [50 to 80] years vs 61 [46 to 72] years), were more likely to be women (2259 [49.0%] vs 2293 [54.9%]), were more likely to have Medicaid insurance (611 [13.3%] vs 1031 [24.7%]), and had higher median (interquartile range) scores on the Neighborhood Deprivation Index (-0.11 [-0.70 to 0.56] vs 0.82 [0.08 to 1.76]) and the Elixhauser Comorbidity Index (21 [0 to 44] vs 22 [0 to 46]). All-cause in-hospital mortality among hospitalized White and Black patients was 23.1% (724 of 3218) and 19.2% (540 of 2812), respectively. After adjustment for age, sex, insurance, comorbidities, neighborhood deprivation, and site of care, there was no statistically significant difference in risk of mortality between Black and White patients (hazard ratio, 0.93; 95% CI, 0.80 to 1.09). CONCLUSIONS AND RELEVANCE: Although current reports suggest that Black patients represent a disproportionate share of COVID-19 infections and death in the United States, in this study, mortality for those able to access hospital care did not differ between Black and White patients after adjusting for sociodemographic factors and comorbidities.

Pacing threshold testing induced ventricular fibrillation following acute rate control of atrial fibrillation.

BACKGROUND: A properly placed stimulus on the T-wave during ventricular repolarization can result in ventricular fibrillation (VF). Initiation of VF with pacing on T-wave is a rare event with a few reported cases in the literature. We present a unique case of induced VF attributed to a pacing stimulus on T-wave during ventricular pacing threshold testing of a permanent pacemaker. CASE REPORT: A 64-year-old woman with persistent atrial fibrillation (AF) and a permanent pacemaker for tachycardia-bradycardia syndrome presented with symptomatic AF with rapid ventricular response. Acute rate control was achieved with intravenous diltiazem. During ventricular pacing threshold testing, noncapture occurred followed by a pacing spike on T-wave initiating VF. Cardiopulmonary resuscitation and defibrillation converted the rhythm to rate-controlled AF. An acute prolongation of the QT was noted and normalized within 12 hours. No antiarrhythmic medications were used. Postevent laboratory values were within normal limits. She was free of ischemia and an echocardiogram revealed normal left ventricular function. She recovered from the event and was discharged with rate-controlled AF. No further pacing-induced arrhythmias have occurred during follow-up pacemaker interrogation and 12-lead electrocardiograms continued to show normal QT intervals. CONCLUSION: Pacemaker-induced VF is an extraordinarily rare complication of cardiac pacing. Alterations in ventricular repolarization with rapid slowing of the heart rate demonstrated by acute prolongation of QT intervals may play a role. This report should alert physicians to the possibility of QT prolongation and an increased risk of ventricular arrhythmias following acute rate control of AF.

Complications associated with generator replacement in response to device advisories.

INTRODUCTION: Device recalls create problems for patients and physicians, for the risks associated with replacement may be greater than the device failure rate. In 2005, Medtronic, Guidant, and St. Jude had implantable cardioverter defibrillator (ICD) recalls on several of their devices. There were no national standards to guide physicians on the management of such patients. We report the reasons for and outcomes of ICD and pacemaker generator changes from our practice resulting from these advisories. METHODS AND RESULTS: After an advisory was issued, the patients with an affected device were contacted, evaluated in the office by one of the electrophysiologists in our group, and a management plan was determined. Two hundred and twenty-two of 1,039 (Medtronic 273, Guidant 766) (21.4%) patients with advisory devices underwent device replacement. Nine minor complications occurred: hematoma managed conservatively (n = 6); local discomfort (n = 1); and incisional infections treated successfully with oral antibiotics (n = 2). Major complications occurred in nine patients (4.1%). Four atrial leads were damaged, two of which were repaired, one during the same procedure and the other at a later date. One patient required a reoperation to tighten a loose ventricular lead set screw. Hematoma requiring evacuation occurred in one patient, and pocket revision was necessary in two patients secondary to severe discomfort due to the positioning of the device in the pocket. One patient had a cerebrovascular accident preoperatively. There were no perioperative deaths or infections requiring system removal. CONCLUSION: Even with experienced operators complications can occur when replacing generators for a device recall. Careful risk assessment for each individual patient should be performed and efforts made to minimize generator changes.

The Utility of Nurse-Managed Extracorporeal Life Support in an Adult Cardiac Intensive Care Unit.

BACKGROUND: The use of extracorporeal life support (ECLS) worldwide has increased exponentially since 2009. The patient requiring ECLS demands an investment of hospital resources, including personnel. Educating bedside nurses to manage ECLS circuits broadens the availability of trained providers. METHODS: Experienced cardiothoracic intensive care unit (CTICU) nurses underwent training to manage ECLS circuits, including volume assessment, treatment of arterial blood gas values, the physiology of ECLS, and recognition of common emergencies. In addition to lectures and a written examination, simulation using water circuits and an ICU model allowed assessment of skills and understanding of concepts. Performance assessments were completed regularly at the bedside, and skills revalidation occurred every 6 months. A sequential cohort of 40 patients was tracked over 1 year. RESULTS: Despite doubling the census of ECLS patients in 1 year, management by specially trained CTICU nurses has positively affected patient care and outcomes. At a single institution, 40 patients had a median of 6 days (interquartile range, 2 to 226 days) of support in 2014, leading to 767 patient-days of support. Survival to hospital discharge increased to 45% in 2014. Most survivors were weaned from support. Neurologic injury was the most common cause of death, followed by failure to qualify for advanced therapies. CONCLUSIONS: With on-going education and assessment, including crisis training, physiology, and cannulation strategies, CTICU nurses can safely operate ECLS circuits and can increase the availability of appropriately trained providers to accommodate the exponential increase in ECLS occurrences without negatively affecting outcomes and generally at a lower cost.

Termination of paroxysmal supraventricular tachycardia by tecadenoson (CVT-510), a novel A1-adenosine receptor agonist.

OBJECTIVES: The aim of this study was to evaluate tecadenoson safety and efficacy during conversion of paroxysmal supraventricular tachycardia (PSVT) to sinus rhythm. BACKGROUND: Tecadenoson (CVT-510), a novel adenosine receptor (Ado R) agonist, selectively activates the A1 Ado R and prolongs atrioventricular (AV) nodal conduction at doses lower than those required to cause A2 Ado R-mediated coronary and peripheral vasodilation. Unlike adenosine, which non-selectively activates all four Ado R subtypes and produces unwanted effects, tecadenoson appears to terminate AV node-dependent supraventricular tachycardias without hypotension and bronchoconstriction. METHODS: In this open-label, multicenter, dose escalation study, tecadenoson was administered to 37 patients (AV node re-entrant tachycardia, n = 29; AV re-entrant tachycardia, n = 8) with inducible PSVT sustained for > or =1 min during an electrophysiology study. Seven regimens (0.3 to 15 microg/kg) of up to two identical tecadenoson intravenous bolus doses were administered. RESULTS: After the first or second bolus, PSVT converted to sustained sinus rhythm for > or =5 min in 86.5% (32/37) of the patients, with 91% (29/32) of the conversions occurring after the first bolus (most within 30 s), coincident with anterograde conduction block in the AV node. No effects on sinus cycle length (SCL) or systolic blood pressure were observed. The atrial-His (AH), but not the His-ventricular (HV) interval was prolonged up to 5 min after the final tecadenoson bolus, returning to baseline by 10 min. Tecadenoson was generally well tolerated. CONCLUSIONS: In this study, tecadenoson rapidly terminated sustained PSVT by depressing AV nodal conduction without causing hypotension. After sinus rhythm restoration, there was minimal AH interval prolongation without HV interval or SCL prolongation.

The disconnect between the guidelines, the appropriate use criteria, and reimbursement coverage decisions: the ultimate dilemma.

Recently, the American College of Cardiology Foundation in collaboration with the Heart Rhythm Society published appropriate use criteria (AUC) for implantable cardioverter-defibrillators and cardiac resynchronization therapy. These criteria were developed to critically review clinical situations that may warrant implantation of an implantable cardioverter-defibrillator or cardiac resynchronization therapy device, and were based on a synthesis of practice guidelines and practical experience from a diverse group of clinicians. When the AUC was drafted, the writing committee recognized that some of the scenarios that were deemed "appropriate" or "may be appropriate" were discordant with the clinical requirements of many payers, including the Medicare National Coverage Determination (NCD). To charge Medicare for a procedure that is not covered by the NCD may be construed as fraud. Discordance between the guidelines, the AUC, and the NCD places clinicians in the difficult dilemma of trying to do the "right thing" for their patients, while recognizing that the "right thing" may not be covered by the payer or insurer. This commentary addresses these issues. Options for reconciling this disconnect are discussed, and recommendations to help clinicians provide the best care for their patients are offered.

Electrocardiographic features and prevalence of bilateral bundle-branch delay.

BACKGROUND: Definitive diagnosis of bilateral bundle-branch delay/block may be made when catheter-induced right bundle-branch block (RBBB) develops in patients with baseline left bundle-branch (LBB) block. We hypothesized that a RBBB pattern with absent S waves in leads I and aVL will identify bilateral bundle-branch delay/block. METHODS AND RESULTS: Fifty patients developing transient RBBB pattern in lead V1 during right heart catheterization were studied. Patients were grouped according to whether the baseline ECG demonstrated a normal QRS, left fascicular blocks, or LBB block pattern. The RBBB morphologies in each group were compared. The prevalence of bilateral bundle-branch delay/block pattern was examined in our hospital ECG database. All patients with baseline normal QRS complexes (n=30) or left fascicular blocks (4 anterior, 5 posterior) developed a typical RBBB pattern. Among the 11 patients with a baseline LBB block pattern, 7 developed an atypical RBBB pattern with absent S waves in leads I and aVL and the remaining 4 demonstrated a typical RBBB. The absence of S waves in leads I and aVL during RBBB was 100% specific and 64% sensitive for the presence of pre-existing LBB block. Among the consecutive 2253 hospitalized patients with RBBB, 34 (1.5%) had the bilateral bundle-branch delay/block pattern. CONCLUSIONS: An ECG pattern of RBBB in lead V1 with absent S wave in leads I and aVL indicates concomitant LBB delay. Pure RBBB and bifascicular blocks are associated with S waves in leads I and aVL.

Association between left ventricular ejection fraction post-cardiac resynchronization treatment and subsequent implantable cardioverter defibrillator therapy for sustained ventricular tachyarrhythmias.

BACKGROUND: Although cardiac resynchronization therapy (CRT) can improve left ventricular ejection fraction (LVEF), it is not known whether a specific level of improvement will predict future implantable cardioverter defibrillator (ICD) therapy. METHODS AND RESULTS: CRT-defibrillator (CRT-D) was implanted in 423 patients at 1 institution between October 2, 2001 and January 19, 2007. A retrospective analysis was performed to evaluate the relationship between post-CRT-D LVEF and ICD therapy for ventricular tachyarrhythmias. A landmark population of 270 patients, with post-CRT-D LVEF measured and no ICD therapy within 1 year of device implantation, was followed for subsequent outcomes. Of these, 22 patients (8.2%) had subsequent appropriate ICD therapy over a median follow-up of 1.5 years. The estimated 2-year risk of appropriate ICD therapy is 3.0% (95% confidence interval [95% CI], 0%-6.3%), 2.1% (95% CI, 0%-5.0%), and 1.5% (95% CI, 0%-3.9%) for post-CRT-D LVEF of 45%, 50%, and 55%, respectively. In patients with a primary prevention indication for CRT-D, the estimated 2-year risk is 3.3% (95% CI, 0%-7.3%), 2.5% (95% CI, 0%-6.1%), and 1.9% (95% CI, 0%-5.1%) for post-CRT-D LVEF of 45%, 50%, and 55%, respectively. CONCLUSIONS: When a CRT responder demonstrates near normalization in LVEF to ≥45%, the incidence of ICD therapy for ventricular arrhythmias becomes low. Future studies are needed to determine whether an ICD is still needed in some of these patients at the time of generator replacement.

Ventricular arrhythmias in the absence of structural heart disease.

Ventricular arrhythmia (VA) in structurally normal hearts can be broadly considered under non-life-threatening monomorphic and life-threatening polymorphic rhythms. Monomorphic VA is classified on the basis of site of origin in the heart, and the most common areas are the ventricular outflow tracts and left ventricular fascicles. The morphology of the QRS complexes on electrocardiogram is an excellent tool to identify the site of origin of the rhythm. Although these arrhythmias are common and generally carry an excellent prognosis, rare sudden death events have been reported. Very frequent ventricular ectopy may also result in a cardiomyopathy in a minority of patients. Suppression of VA may be achieved using calcium-channel blockers, beta-adrenergic blockers, and class I or III antiarrhythmic drugs. Radiofrequency ablation has emerged as an excellent option to eliminate these arrhythmias, although certain foci including aortic cusps and epicardium may be technically challenging. Polymorphic ventricular tachycardia (VT) is rare and generally occurs in patients with genetic ion channel disorders including long QT syndrome, Brugada syndrome, catecholaminergic polymorphic VT, and short QT syndrome. Unlike monomorphic VT, these arrhythmic syndromes are associated with sudden death. While the cardiac gross morphology is normal, suggesting a structurally normal heart, abnormalities exist at the molecular level and predispose them to arrhythmias. Another fascinating area, idiopathic ventricular fibrillation and early repolarization syndrome, are undergoing research for a genetic basis.