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Abstract Background Indications for the primary prevention of sudden death using an implantable cardioverter defibrillator (ICD) are based predominantly on left ventricular ejection fraction (LVEF). However, right ventricular ejection fraction (RVEF) is also a known prognostic factor in a variety of structural heart diseases that predispose to sudden cardiac death. We sought to investigate the relationship between right and left ventricular parameters (function and volume) measured by cardiovascular magnetic resonance (CMR) among a broad spectrum of patients considered for an ICD. Methods In this retrospective, single tertiary-care center study, consecutive patients considered for ICD implantation who were referred for LVEF assessment by CMR were included. Right and left ventricular function and volumes were measured. Results In total, 102 patients (age 62±14 years; 23% women) had a mean LVEF of 28±11% and RVEF of 44±12%. The left ventricular and right ventricular end diastolic volume index was 140±42 mL/m2 and 81±27 mL/m2 , respectively. Eighty-six (84%) patients had a LVEF <35%, and 63 (62%) patients had right ventricular systolic dysfunction. Although there was a significant and moderate correlation between LVEF and RVEF ( r =0.40, p <0.001), 32 of 86 patients (37%) with LVEF <35% had preserved RVEF, while 9 of 16 patients (56%) with LVEF ≥35% had right ventricular systolic dysfunction (Kappa=0.041). Conclusions Among patients being considered for an ICD, there is a positive but moderate correlation between LVEF and RVEF. A considerable proportion of patients who qualify for an ICD based on low LVEF have preserved RVEF, and vice versa.

Abstract Background The association between influenza vaccination and implantable cardiac defibrillator (ICD) therapies during influenza season is not known and is described in this study. Understanding this association is important since reduction in ICD therapies during influenza season via use of influenza vaccination would benefit patients physically and psychologically. Methods Patients presenting to the Sunnybrook Health Sciences Center ICD clinic between September 1st, 2011 and November 31st, 2011 were asked to complete a survey evaluating their use of the influenza vaccine. The number of patients with any ICD therapy and the total number of ICD therapies in the six months before and the three months during the 2010–2011 influenza season were determined. Poisson regression analysis was employed to assess differences in the average number of ICD therapies received during the influenza season based on vaccine status (vaccinated vs. unvaccinated). The analysis was repeated after limiting the cohort to patients with a left ventricular ejection fraction ≤35%. Results A total of 229 patients completed the survey, 78% of whom received the influenza vaccine. Four patients had more than one ICD shock during the study period. Electrical storm was rare ( n =2). A trend toward more ICD therapies (unadjusted incident rate ratio (IRR)=3.2; P =0.07) and appropriate ICD shocks (unadjusted IRR=9.0; P =0.17) was noted for unvaccinated compared to vaccinated patients. This association persisted when analysis was limited to patients with a left ventricular ejection fraction ≤35% (all ICD therapies: unadjusted IRR=5.8; P =0.045; adjusted IRR=2.6; P =0.33). No patient who received the influenza vaccine, and had a reduced ejection fraction, received an approprite ICD shock during influenza season (unadjusted P <0.002). Conclusion A trend toward more ICD therapies during influenza season was observed in patients who did not receive the influenza vaccine compared to those who did. The association was stronger in patients who received appropriate ICD shocks and in patients with left ventricular systolic dysfunction. Further work to confirm these findings is recommended.

Abstract Background There is increasing interest in performing left atrial appendage (LAA) occlusion at the time of atrial fibrillation (AF) ablation procedures. However, to date there has been no description of the acute changes to the LAA immediately following pulmonary vein (PV) isolation and additional left atrium (LA) substrate modification. This study assessed changes in the size and tissue characteristics of the LAA ostium in patients undergoing PV isolation. Methods This series included 8 patients who underwent cardiovascular magnetic resonance evaluation of the LA with delayed enhancement magnetic resonance imaging and contrast enhanced 3-D magnetic resonance angiography pre-, within 48 h of, and 3 months post ablation. Two independent cardiac radiologists evaluated the ostial LAA diameters and area at each time point in addition to the presence of gadolinium enhancement. Results Compared to pre-ablation values, the respective median differences in oblique diameters and LAA area were +1.8 mm, +1.7 mm, and +0.6 cm2 immediately post ablation (all NS) and −2.7 mm, −2.3 mm, and −0.5 cm2 at 3 months (all NS). No delayed enhancement was detected in the LAA post ablation. Conclusion No significant change to LAA diameter, area, or tissue characteristics was noted after PV isolation. While these findings suggest the safety and feasibility of concomitant PV isolation and LAA device occlusion, the variability in the degree and direction of change of the LAA measurements highlights the need for further study.

A 25-year-old man with a medical history of propionic acidemia was brought to hospital after he collapsed while jogging. He was unresponsive, received immediate bystander cardiopulmonary resuscitation and was defibrillated by paramedics from an initial rhythm of ventricular fibrillation with successful return of spontaneous circulation. He had been diagnosed with propionic acidemia at two years of age when he presented with developmental delay, and metabolic work-up showed the classic profile of 3-OH-propionic and methylcitric acids on analysis of organic acids in urine, low carnitine with increased propionylcarnitine on acylcarnitine profile and increased glycine on quantitative amino acid analysis of plasma. At the time of the patient's witnessed cardiac arrest, initial laboratory investigations showed an anion gap metabolic acidosis and lactic acidemia (lactate level 7.9 mM). Although the patient's ventricular arrhythmia may have been due to a reversible cause, we decided to proceed with insertion of an implantable cardioverter-defibrillator. We based this on

We examined the relations between right bundle branch block (RBBB) and clinical characteristics, management, and outcomes among a broad spectrum of patients with acute coronary syndrome (ACS). Admission electrocardiograms of patients enrolled in the Global Registry of Acute Coronary Events (GRACE) electrocardiogram substudy and the Canadian ACS Registry I were analyzed independently at a blinded core laboratory. We performed multivariable logistic regression analysis to assess the independent prognostic significance of admission RBBB on in-hospital and 6-month mortality. Of 11,830 eligible patients with ACS (mean age 65; 66% non–ST-elevation ACS), 5% had RBBB. RBBB on admission was associated with older age, male sex, more cardiovascular risk factors, worse Killip class, and higher GRACE risk score (all p <0.01). Patients with RBBB less frequently received in-hospital cardiac catheterization, coronary revascularization, or reperfusion therapy (all p <0.05). The RBBB group had higher unadjusted in-hospital (8.8% vs 3.8%, p <0.001) and 6-month mortality rates (15.1% vs 7.6%, p <0.001). After adjusting for established prognostic factors in the GRACE risk score, RBBB was a significant independent predictor of in-hospital death (odds ratio 1.45, 95% CI 1.02 to 2.07, p = 0.039), but not cumulative 6-month mortality (odds ratio 1.29, 95% CI 0.95 to 1.74, p = 0.098). There was no significant interaction between RBBB and the type of ACS for either in-hospital or 6-month mortality (both p >0.50). In conclusion, across a spectrum of ACS, RBBB was associated with preexisting cardiovascular disease, high-risk clinical features, fewer cardiac interventions, and worse unadjusted outcomes. After adjusting for components of the GRACE risk score, RBBB was a significant independent predictor of early mortality.

There is substantial variation in the management of atrial fibrillation (AF) in the emergency department (ED), particularly whether these patients are admitted to hospital. We sought to identify factors that predict admission and to examine the relationship between AF admission and outcomes. We performed a retrospective cohort analysis of patients ≥20 years of age who had an index ED visit with a primary diagnosis of AF from between April 1, 2005, and March 31, 2010, in Ontario, Canada. We excluded patients who died during the index ED visit or hospitalization. A hierarchical logistic regression model was used to determine predictors of hospital admission during the index ED visit. A propensity-matched analysis was used to test for associations between hospital admission and 1-year outcomes. The cohort consisted of 33,699 patients, of whom 16,270 (48.3%) were admitted to hospital. Substantial variation was seen across the 154 hospitals, with admission rates ranging from 3.0% to 91.0%. Admitted patients had higher rates of comorbidities compared to discharged patients. Mortality rates at 1 year were significantly higher in matched admitted versus discharged patients (hazard ratio 1.45, 95% CI 1.33-1.57, P < .001), as were all-cause hospitalizations (hazard ratio 1.18, 95% CI 1.13-1.22, P < .001). Wide practice variation was observed between hospitals in terms of the proportion of patients admitted. Our data suggest that selected patients when discharged have similar or improved outcomes compared to those who are initially admitted. Future research is needed to better standardize admission/discharge decisions for AF patients in the ED.