Brady, Peter A.

Background: Atrial fibrillation (AF) is common in HCM yet the mechanisms are poorly understood but are likely secondary to either the consequences of left atrial structural remodeling (LASR) or myopathy, or triggers arising from pulmonary and other thoracic veins. The presence and severity of LASR as characterized by left atrial strain (LA ϵ), and its relationship to AF in HCM, has not been determined. Therefore, we measured LA ϵ and strain rate (SR) in Pts with HCM both with (AF+) and without (AF−) prior AF and compared these measures to those in age and gender matched controls without HCM or AF. Methods: Two-dimensional speckle-derived LA longitudinal peak ϵ, SR during systole (SR S ), early (SR E ) and late diastole (SR A ) were measured at the basal and mid portions of the lateral, septal, and posterior LA walls using Vector Velocity Imaging during sinus rhythm and were averaged. Results: Mean age of Pts in each of the matched groups was 56 ± 2 years (16 males; 59%). Significant left ventricular outflow tract obstruction was present in all Pts with HCM. Diastolic dysfunction was similar in both HCM groups and worse when compared to controls. Peak LA 3 , SR S , SR E , and SR A for each group is shown (table 1 ). HCM was associated with significantly lower LA ϵ and SR compared to controls. Although LA size was increased in Pts with HCM when compared to controls there was no correlation between LA size and ϵ or SR (p>0.05 for all). No differences in LA ϵ and SR were found between AF+ versus AF− Pts. Conclusion: HCM is associated with LASR as determined by decreased LA ϵ and SR. However, LA ϵ and SR were similar in AF+ versus AF− Pts suggesting that the occurrence of AF in HCM is not due to LASR alone. Table 1. Left Atrial Strain and Strain Rate in Hypertrophic Cardiomyopathy

Introduction: Idiopathic Dilated (DCM) and hypertrophic cardiomyopathies (HCM) are leading causes of sudden cardiac death. The incidence and prevalence of both DCM and HCM were originally estimated in Olmsted County, MN over 1975-1984. Incidence was 6.0 and prevalence was 36.5 per 100,000 person-years, for DCM; with incidence and prevalence rates of 2.5 and 19.7 per 100,000 person-years for HCM. This study aims to determine the incidence and mortality rates of individuals diagnosed with HCM and DCM in Olmsted County, MN from 1984 to 2016. Methods: The Rochester Epidemiology Project is a validated long term medical record linkage system that collects and links medical information for the approximately 145000 residents of Olmsted County, Minnesota. Using this database and the Electronic Health Record systems at Mayo Clinic and Olmsted Medical Center in Rochester, MN, we manually reviewed and validated the medical records of 4440 patients. This cohort includes all patients with any mention of a cardiomyopathy based on ICD and HICDA codes during the period 1984 to 2016. Data were summarized with mean and standard deviation, frequency and percentage and compared between groups using two sample t-test for continuous data and chi-square for proportions. Survival was computed using Kaplan-Meier methods and compared to expected survival based on age and gender. Incidence was computed using Olmsted County population numbers during the time period and adjusted to the US 1980 white population to allow for comparison with the previous study. Results: The calculated crude incidence rate for DCM and HCM are 10.1 and 7.8 per 100,000 respectively. Incidence rates adjusted for comparison to US 1980 white population (age and sex adjusted) are 10.4 (95% CI: 9.3-11.4) and 8.0 (95% CI: 7.1-8.8) per 100,000 person-years, respectively. The observed number of deaths in this cohort (HCM and DCM) was 420 vs 194 expected. Conclusions: Calculated incidence, both crude and adjusted rates are higher than previously estimated rates. The crude incidence rate for HCM is almost 4-fold higher than that for DCM is 2.4 times higher than the original estimate by Codd et al. Individuals with cardiomyopathies were found to have a higher overall mortality rate than the general population with an observed to expected hazard ratio of 1.73 (95% CI 1.49-2.01, p<0.001) for DCM and 1.44 (95% CI 1.21-1.71, p<0.001) for HCM. Our findings suggest that previous studies may have underestimated the true burden of HCM and DCM in the population which has important implications for healthcare provision and cost.

Background Aortic stenosis (AS) affects, and is associated with significant comorbidity and mortality, including sudden cardiac death (SCD) from unknown mechanisms. However, it is difficult to predict which patients with AS will suffer a SCD event. Anemia and low iron are known risk factors for mortality in heart failure populations and AS. We hypothesized that anemia in patients with AS is associated with increased risk of SCD. Purpose Understand the relationship and prognostic implications between anemia and SCD in patients with severe AS. Methods and Results We selected 8,144 of 10,850 patients with severe AS (mean transvalvular gradient ≥40 mmHg or peak velocity ≥4 m/s or calculated valve area < 1 cm 2 ) from the Mayo Clinic Aortic Stenosis Registry, which includes all consecutive patients with severe AS over the time period January 1 st , 1983 to September 30 th , 2015. Subjects in this analysis (median age 76 years and 57% male) were diagnosed starting in 1995 and had hemoglobin (Hb) measurements within one year of diagnosis and prior to intervention. The mean Hb level was 12.8 (± 1.9) g/dL. The prevalence of anemia (Hb<13.0g/dL for men, <12.0g/dL for women) was 40%, 14% microcytic, 20% macrocytic, with the remainder normocytic. Of the 8,144 patients, a total of 4,440 died (10‐year survival 39%; and 240 were confirmed as SCD events [10 year cumulative incidence 4%]). Anemia was associated with increased all‐cause mortality (HR 1.87, 95% CI 1.76–1.99, P=<0.001) and increased SCD events (HR 1.58, 95% CI 1.22–2.06, P=<0.001) in patients with severe AS. Every SD decrease in Hb (1.9 g/dL) was associated with an increased risk of SCD (HR 1.42, 95% CI 1.24–1.62, P<0.001). Conclusions Anemia is highly prevalent in patients with severe aortic stenosis and is independently associated with increased all‐cause mortality, and more specifically with increased SCD risk. Possible mechanisms include anemia aggrevating myocardial hypoxia, increasing propensity for arrhythmia and abnormal Bezold‐Jarisch reflex mismatch. Anemia may be a useful prognostic marker and a potential therapeutic target in patients with severe AS. Support or Funding Information CAAC is supported by AHA17POST33400211 and NIH HL134885. This study was supported by a grant from the Department of Cardiovascular Medicine, Mayo Clinic Rochester. This abstract is from the Experimental Biology 2018 Meeting. There is no full text article associated with this abstract published in The FASEB Journal .

Abstract Background: Left atrial (LA) function can be impaired by the atrial fibrillation (AF) ablation and might be associated with the risk of recurrence. We sought to determine whether the post-procedural changes in LA function impact the risk of recurrence following AF ablation. Methods: We retrospectively reviewed patients who underwent AF ablation between 2009 and 2011 and underwent transthoracic echocardiography before ablation, 1-day and 3-month after ablation. Peak left atrial contraction strain (PACS) and left atrial emptying fraction (LAEF) were evaluated during sinus rhythm and compared across the three time points. The primary endpoint was atrial tachyarrhythmia recurrence after ablation. Results: Out of 144 patients were enrolled (mean age 61±11 years, 77% male, 46% persistent AF). PACS and LAEF initially decreased 1-day following ablation but partially recovered within 3 months in PAF patients, with a similar trend in the PerAF patients. After median 24 months follow-up, 68 (47%) patients had recurrence. Patients with recurrence had higher PACS1-day than that in non-recurrence subjects (-10.9±5.0%%vs. -13.4±4.7, p=0.003). PACS1-day -12% distinguished recurrence cases with a sensitivity of 67.7% and specificity of 60.5%. The Kaplan-Meier curves showed significant difference in 5-year cumulative probability of recurrence between those with PACS≥ -12 % and PACS < -12% (log rank p<0.0001). Multivariate regression showed that PACS1-day was an independent risk factor of arrhythmia recurrence. Conclusions: Left atrial function deteriorates immediately following AF ablation and partially recovers in 3 months but remains abnormal in the majority of patients. PACS1-day post procedure predicts arrhythmia recurrence at long-term follow-up.

Abstract Objectives Right ventricular (RV) failure occurring after left ventricular assist device (LVAD) implantation is associated with increased mortality. Purpose We sought to determine whether RV strain by echocardiography predicts outcomes following LVAD. Methods Consecutive patients who underwent continuous flow LVAD placement at our clinic between February 2007 and October 2018 were included. Patients with complex congenital heart disease and arrhythmogenic right ventricular cardiomyopathy were excluded. Baseline characteristics, pre-operative hemodynamic catheterization (1 week) transthoracic echocardiography (1 month) measurements were obtained from the medical record. Speckle tracking RV free wall longitudinal 2D strain was measured using TomTec Imaging System. Univariate and multivariable analysis performed to identify predictors of mortality following LVAD. Results The study group was comprised of 323 patients (mean age 60.8±11.5, 79.9% male) of which 256 had adequate image quality for RV strain. RV strain was impaired in most patients (mean −11.7±3.47). RV strain of −8.1% was identified as predictive of poor outcomes. RV strain did not correlate with other measures of RV dysfunction including pulmonary artery pulsatility index (PAPi) and RVFAC. After adjusting for PAPi, RA pressure, and clinical cumulative risk scores (Matthews, Kormos and Lietz-Miller) impaired RV free wall longitudinal strain (OR: 1.14; 95% CI: 1.01–1.29, p=0.025), tricuspid regurgitation (by vena contracta width (TRvc) (OR: 1.19; 95% CI: 1.05–1.36, p=:0.0021) and smaller LVEDD (OR: 0.95; 95% CI: 0.92–0.99, p:0.023) predicted 30-day all-cause mortality and RV failure. Decreased RV free wall strain also predicted peri-operative mortality (22.58% vs. 4.89%, p=0.0003) and prolonged inotropic support (247.0.±277.4 vs. 122.8±139.3, p=0.024). Conclusions RV free wall strain is a non-invasive independent predictor of 30-day adverse outcomes (RV failure or all-cause mortality) Routine measurement of RV free strain may identify those patients at highest risk for early and long term mortality following LVAD. Funding Acknowledgement Type of funding source: None

Abstract Introduction Cardiopulmonary exercise testing (CPET) has an established role in the clinical evaluation of exercise intolerance and in the risk stratification of patients with heart failure. There is limited data assessing its prognostic utility in the evaluation of patients with Arrhythmogenic Right Ventricular Cardiomyopathy (ARVC). The predisposition of patients with ARVC for ventricular arrhythmias and sudden cardiac death has led to recommendations for exercise restrictions and limits our understanding of how the impairment in oxygen extraction and cardiac output impact disease progression and outcomes in these patients. Purpose We examined the association between CPET indices and event free survival (time to mortality or cardiac transplantation) in patients with Arrhythmogenic Right Ventricular Cardiomyopathy (ARVC). Methods Patients with definite ARVC based on 2010 task force criteria and genetically positive were enrolled into our institutional ARVC registry. 43 patients underwent CPET and have been included in our analyses. Indications for testing included: Evaluation of exercise-induced palpitations/arrhythmias or syncope (37%), pharmacotherapy optimization (28%), heart failure evaluation (19%), and ARVC management decisions (16%). CPET data (peak oxygen consumption (pVO2), respiratory exchange ratio (RER), and ventilatory efficiency (VE/VCO2) were assessed in patients at time of initial evaluation. Median follow-up time was 4.9 years (IQR 9 years). Results 126 patients were studied (age 43.7+ 15 yrs; 41% women; LVEF 57+ 11%; 15% with LVEF &lt;50%) and 43 underwent CPET evaluation. 41 patients (95%) performed at near maximal effort (RER &gt;1) and no fatal events were reported during testing. During the follow up period, the outcome (death or cardiac transplantation) occurred in 31 patients. On Kaplan Meier analysis, pVO2 ≤14 mL/kg/min was associated with worse outcomes (unadjusted p&lt;0.001). Peak oxygen consumption (pVO2) ≤14 mL/kg/min and ventilatory efficiency (VE/VCO2) &gt;34 were associated with shorter event free survival (HR 5.58, p=0.002 and HR 5.56 p=0.005, respectively). After adjusting for age, sex, and right ventricular function, the association between peak oxygen consumption (pVO2) and event free survival remained significant (p=0.02). Conclusions In patients with ARVC, peak oxygen consumption (pVO2) was a prognostic indicator of worse outcomes. Our findings suggest a potential role for pVO2 in disease surveillance and early assessment for advanced heart failure therapies. Figure 1. KM plot pVO2 & event free survival Funding Acknowledgement Type of funding source: Other. Main funding source(s): Mayo Clinic

Arrhythmogenic cardiomyopathy (ACM) is an inherited cardiomyopathy characterised by ventricular arrhythmia and an increased risk of sudden cardiac death (SCD). Numerous genetic determinants and phenotypic manifestations have been discovered in ACM, posing a significant clinical challenge. Further to this, wider evaluation of family members has revealed incomplete penetrance and variable expressivity in ACM, suggesting a complex genotype-phenotype relationship. This review details the genetic basis of ACM with specific genotype-phenotype associations, providing the reader with a nuanced perspective of this condition; whilst also proposing a future roadmap to delivering precision medicine-based management in ACM.

AbstractBackgroundInappropriate sinus tachycardia (IST) remains a clinical challenge because patients often are highly symptomatic and not responsive to medical therapy.ObjectiveTo study the safety and efficacy of stellate ganglion (SG) block and cardiac sympathetic denervation (CSD) in patients with IST.MethodsTwelve consecutive patients who had drug‐refractory IST (10 women) were studied. According to a prospectively initiated protocol, five patients underwent an electrophysiologic study before and after SG block (electrophysiology study group). The subsequent seven patients had ambulatory Holter monitoring before and after SG block (ambulatory group). All patients underwent SG block on the right side first, and then on the left side. Selected patients who had heart rate reduction ≥15 beats per minute (bpm) were recommended to consider CSD.ResultsThe mean (SD) baseline heart rate (HR) was 106 (21) bpm. The HR significantly decreased to 93 (20) bpm (P = .02) at 10 minutes after right SG block and remained significantly slower at 97(19) bpm at 60 minutes. Left SG block reduced HR from 99 (21) to 87(16) bpm (P = .02) at 60 minutes. SG block had no significant effect on blood pressure or HR response to isoproterenol or exercise (all P > .05). Five patients underwent right (n = 4) or bilateral (n = 1) CSD. The clinical outcomes were heterogeneous: one patient had complete and two had partial symptomatic relief, and two did not have improvement.ConclusionSG blockade modestly reduces resting HR but has no significant effect on HR during exercise. Permanent CSD may have a modest role in alleviating symptoms in selected patients with IST.

The efficacy with which sulfonylurea drugs inhibit cardiac ATP-sensitive K+ (KATP) channels is reduced during metabolic compromise and cellular contracture. Disruption of the actin microfilament network, which occurs under similar conditions, reduces the sensitivity of the channel toward intracellular ATP. To investigate whether a disrupter of actin microfilaments could also affect the responsiveness of the KATP channel to sulfonylurea drugs, single-channel currents were measured in the inside-out configuration of excised patches from guinea pig ventricular myocytes. Treatment of the internal side of patches with deoxyribonuclease (DNase) I (100 micrograms/ml), which forms complexes with G actin and prevents actin filament formation, antagonized sulfonylurea-induced inhibition of KATP channels that was coupled with a loss of sensitivity to ATP. The apparent dissociation constant and Hill coefficient for the inhibitory effect of glyburide, a prototype sulfonylurea, on KATP-channel opening were, respectively, 0.13 microM and 0.95 before and 2.7 microM and 0.98 after DNase treatment. DNase did not alter intraburst kinetic properties of the channel. When DNase was denatured or coincubated with purified actin (200 micrograms/ml), it no longer decreased glyburide-induced channel inhibition. This suggests that sulfonylurea-inhibitory gating of cardiac KATP channels may also be regulated through a mechanism involving subsarcolemmal actin microfilament networks.