Exercise capacity and paroxysmal atrial fibrillation in patients with hypertrophic cardiomyopathy

The Association of Epicardial Adipose Tissue Volume and Atrial Fibrillation in Patients With Hypertrophic Cardiomyopathy: As Assessed by Cardiac MR

BACKGROUND

Epicardial adipose tissue (EAT) is a metabolically active visceral fat linked to cardiovascular disease. Prior studies demonstrated the predictive value of EAT volume (EATV) in atrial fibrillation (AF) among hypertrophic obstructive cardiomyopathy patients.

PURPOSE

To investigate the association between EATV and AF in hypertrophic cardiomyopathy (HCM).

STUDY TYPE

Retrospective.

POPULATION

Two hundred and twenty-four HCM patients (including 79 patients with AF and 145 patients without AF, 154 men) and 80 healthy controls (54 men).

FIELD STRENGTH/SEQUENCE

3.0 T scanner; balanced steady-state free precession (SSFP) cine sequence, gradient echo.

ASSESSMENT

EAT thickness was assessed in the 4-chamber and basal short-axis planes. EAT volume was calculated by outlining the epicardial border and visceral pericardium layer on short-axis cine images.

STATISTICAL TESTS

Shapiro-Wilk test, Student's t test or the Mann-Whitney U test, chi-square test or Fisher's exact test, Multivariate linear regression analyses, Multivariable binary logistic regression analysis. Intraclass correlation coefficient. Significance was determined at P < 0.05.

RESULTS

EATV and EAT volume index (EATVI) were significantly greater in HCM patients with AF than those without AF (126.6 ± 25.9 mL vs. 90.5 ± 24.5 mL, and 73.0 ± 15.9 mL/m2 vs. 51.3 ± 13.4 mL/m2). EATVI was associated with AF in multivariable linear regression analysis among HCM patients (β = 0.62). Multivariable logistic regression analysis revealed that compared to other indicators, the area under curve (AUC) of EATVI was 0.86 (cut-off, 53.9 mL/m2, 95% CI, 0.80-0.89), provided a better performance, with the sensitivity of 96.2% and specificity of 58.6%. The combined model exhibited superior association with AF presence compared to the clinical model (AUC 0.96 vs. 0.76) and the imaging model (AUC 0.96 vs. 0.93).

DATA CONCLUSION

EATVI was associated with AF. EATVI was significantly correlated with incident AF, and provided a better performance in HCM patients compared to other indicators.

EVIDENCE LEVEL

3 TECHNICAL EFFICACY: Stage 2.

The abnormalities of free fatty acid metabolism in patients with hypertrophic cardiomyopathy, a single-center retrospective observational study

BACKGROUND

Previous studies have shown the importance of energy deficiency and malfunctioning mitochondria in the pathophysiology of hypertrophic cardiomyopathy (HCM). There has been a little research into the relationship between plasma free fatty acids (FFA), one of the heart's main energy sources, and HCM. We evaluated its clinical importance in HCM to see if there was a link between plasma FFA metabolism and HCM.

METHODS

In a single-center retrospective observational study, we investigated 420 HCM patients diagnosed at Beijing Anzhen Hospital between January 1, 2018, and December 31, 2022. Meanwhile, 1372 individuals without HCM (non-HCM) were recruited. 391 non-HCM patients were chosen as controls via a propensity score matching (PSM) study with a 1:1 ratio.

RESULTS

FFA in HCM patients showed statistically significant correlations with creatinine (r = 0.115, p = 0.023), estimated GFR (r=-0.130, p = 0.010), BNP (r = 0.152, p = 0.007), LVEF (r=-0.227, p < 0.001), LVFS (r=-0.160, p = 0.002), and LAD (r = 0.112, p = 0.028). Higher FFA levels were found in HCM patients who had atrial fibrillation and NYHY functional classes III or IV (p = 0.015 and p = 0.022, respectively). In HCM patients, multiple linear regression analysis revealed that BNP and LVEF had independent relationships with increasing FFA (Standardized = 0.139, p = 0.013 and =-0.196, p < 0.001, respectively).

CONCLUSIONS

Among HCM patients, the plasma FFA concentration was lower, and those with AF and NYHY functional class III or IV had higher FFA levels, and LVEF and BNP were independently associated with increasing FFA. The findings of the study should help inspire future efforts to better understand how energy deficiency contributes to hypertrophic cardiomyopathy (HCM) development.

The prognostic value of peak oxygen uptake in obstructive hypertrophic cardiomyopathy: a literature review to inform economic model development

AIMS

Patients with obstructive hypertrophic cardiomyopathy (oHCM) experience significant clinical burden which is associated with a high economic burden. Peak oxygen uptake (pVO2), measured by cardiopulmonary exercise testing, is used to quantify functional capacity, and has been studied as a primary endpoint in recent clinical trials. This study aimed to gather evidence to consolidate the prognostic value of pVO2 in oHCM and to assess whether it is feasible to predict health outcomes in an economic model based on changes in pVO2.

METHODS

A targeted literature review was conducted in MEDLINE (via PubMed) and Embase databases to identify evidence on the prognostic value of pVO2 as a surrogate health outcome to support future oHCM economic model development. Following screening, study characteristics, population characteristics, and pVO2 prognostic association data were extracted.

RESULTS

A total of 4,687 studies were identified. In total, 3,531 and 538 studies underwent title/abstract and full-text screening, respectively, of which 151 were included and nine of these were in hypertrophic cardiomyopathy (HCM); only three studies focused on oHCM. The nine HCM studies consisted of one systematic literature review and eight primary studies reporting on 27 potentially predictive relationships from a pVO2-based metric with clinical outcomes including all-cause mortality, cardiovascular mortality, sudden cardiac death, transplant, paroxysmal, and permanent atrial fibrillation. pVO2 was described as a predictor of single and composite endpoints, in three and six studies, respectively, with one study reporting on both.

LIMITATIONS

This study primarily uses systemic literature review methods but does not qualify as one due to not entailing parallel reviewers during title-abstract and full-text stages of review.

CONCLUSION

The findings of this study suggest pVO2 is predictive of multiple health outcomes, providing a rationale to use pVO2 in the development of an economic model.

The role of cardiopulmonary exercise testing in risk stratification and prognosis of atrial fibrillation: a scoping review of the literature

BACKGROUND

Cardiopulmonary exercise testing (CPET) is a significant tool for evaluating exercise capacity in healthy individuals and in various pulmonary and cardiovascular conditions, quantifying symptoms and predicting outcomes. Atrial fibrillation (AF) poses a significant burden on patients and health systems; a research marathon is ongoing for discovering the pathophysiologic substrate, natural history, prognostic tools and optimal treatment strategies for AF. Among the plethora of variables measured during CPET, there is a series of parameters of interest concerning AF.

METHODS

We conducted a scoping review aiming to identify significant CPET-related parameters linked to AF, as well as indicate the impact of other cardiac disease-related variables. We searched PubMed from its inception to 12 January 2022 for reports underlining the contribution of CPET in the assessment of patients with AF. Only clinical trials, observational studies and systematic reviews were included, while narrative reviews, expert opinions and other forms of manuscripts were excluded.

RESULTS

In our scoping review, we report a group of heterogeneous, thus noteworthy parameters relevant to the potential contribution of CPET in AF. CPET helps phenotype AF populations, evaluates exercise capacity after cardioversion or catheter ablation, and assesses heart rate response to exercise; peak VO₂ and VE/VCO₂, commonly measured indices during CPET, also serve as prognostic tools in patients with AF and heart failure.

CONCLUSIONS

CPET seems to hold a clinically important predictive value for future cardiovascular events both in patients with pre-existing cardiac conditions and in healthy individuals. CPET variables may play a fundamental role in the prediction of future AF-related events.

Absent fourth heart sound as a marker of adverse events in hypertrophic cardiomyopathy with sinus rhythm

BACKGROUND

Patients with hypertrophic cardiomyopathy (HCM) in sinus rhythm commonly show the fourth heart sound (S4). The lack of S4 may be a marker of impaired atrial function in HCM patients with sinus rhythm.

METHODS AND RESULTS

This retrospective study consisted of 47 patients with HCM who had undergone phonocardiography and a cardiopulmonary exercise test. The primary outcome was a composite of cardiac death, stroke, hospitalization for worsening heart failure, and newly developed atrial fibrillation (AF). S4 was detected in 38 of 43 patients with sinus rhythm (88%). Peak oxygen consumption was the highest in 38 sinus rhythm patients with S4 (23.6 ± 5.6 mL/kg/min), middle in five sinus rhythm patients without S4 (19.3 ± 6.7 mL/kg/min), and lowest in four patients with AF (15.7 ± 3.3 mL/kg/min, p = 0.01). After a median of 40.5 months, the incidence of the primary outcome was higher in patients without S4 than in those with S4 (33% vs. 8%; hazard ratio, 6.17; 95% confidence interval, 1.02 - 37.4; p = .04) and higher in sinus rhythm patients without S4 than in those with S4 (60% vs. 8%; hazard ratio, 12.05; 95% confidence interval, 2.31 - 71.41; p = .007).

CONCLUSIONS

The absence of S4 on phonocardiography was associated with impaired exercise tolerance and adverse cardiac events in HCM patients with sinus rhythm.

Prognostic relevance of exercise testing in hypertrophic cardiomyopathy. A systematic review

BACKGROUND

Cardiopulmonary exercise test (CPET) is indicated as part of the assessment in hypertrophic cardiomyopathy (HCM) patients and stress echocardiography is often used to assess symptoms. However, the role of exercise testing for prognostic stratification in HCM is still not established.

AIMS

To systematically review the evidence on the role of exercise testing for prognostic stratification in hypertrophic cardiomyopathy.

METHODS

A systematic review was conducted for eligible publications, between 2010 and 2020, that included evaluation of outcomes and prognosis. In these studies, patients underwent exercise echocardiography and/or cardiopulmonary exercise testing, performed according to predefined protocols. Diverse parameters were assessed in order to determine which were relevant for the prognosis. Analyzed outcomes included death from any cause, sudden cardiac death (SCD) and equivalents, cardiovascular death, heart failure requiring hospitalization or progression to New York Heart Association classes III or IV, cardiac transplantation, non-sustained ventricular tachycardia, stroke, myocardial infarction and invasive septal reduction therapy.

RESULTS

Eighteen publications were included, corresponding to a total of 7525 patients. The mean follow-up period varied between 1 and 8 years. The main findings of these studies revealed that the major predictors of outcomes were abnormal heart rate recovery, abnormal blood pressure response exercise induced wall motion abnormalities, lower peak VO2, higher VE/VCO2, and pulmonary hypertension/exercise-induced pulmonary hypertension.

CONCLUSION

Although most studies concluded that exercise test results are useful to determine prognosis in HCM, further investigation is needed regarding whether it adds independent value to the current risk stratification strategies.

Development and Validation of a Clinical Predictive Model for Identifying Hypertrophic Cardiomyopathy Patients at Risk for Atrial Fibrillation: The HCM-AF Score

[Figure: see text].

Cardiopulmonary Exercise Test in Patients with Hypertrophic Cardiomyopathy: A Systematic Review and Meta-Analysis

BACKGROUND

Patients with chronic diseases frequently adapt their lifestyles to their functional limitations. Functional capacity in Hypertrophic Cardiomyopathy (HCM) can be assessed by stress testing. We aim to review and analyze the available data from the literature on the value of Cardiopulmonary Exercise Test (CPET) in HCM. Objective measurements from CPET are used for evaluation of patient response to traditional and new developing therapeutic measurements.

METHODS

A systematic review of the literature was conducted in PubMed, Web of Science and Cochrane in Mar-20. The original search yielded 2628 results. One hundred and two full texts were read after the first screening, of which, 69 were included for qualitative synthesis. Relevant variables to be included in the review were set and 17 were selected, including comorbidities, body mass index (BMI), cardiac-related symptoms, echocardiographic variables, medications and outcomes.

RESULTS

Study sample consisted of 69 research articles, including 11,672 patients (48 ± 14 years old, 65.9%/34.1% men/women). Treadmill was the most common instrument employed (n = 37 studies), followed by upright cycle-ergometer (n = 16 studies). Mean maximal oxygen consumption (VO2max) was 22.3 ± 3.8 mL·kg^-1·min^-1. The highest average values were observed in supine and upright cycle-ergometer (25.3 ± 6.5 and 24.8 ± 9.1 mL·kg^-1·min^-1; respectively). Oxygen consumption in the anaerobic threshold (ATVO2) was reported in 18 publications. Left ventricular outflow tract gradient (LVOT) > 30 mmHg was present at baseline in 31.4% of cases. It increased to 49% during exercise. Proportion of abnormal blood pressure response (ABPRE) was higher in severe (>20 mm) vs. mild hypertrophy groups (17.9% vs. 13.6%, p < 0.001). Mean VO2max was not significantly different between severe vs. milder hypertrophy, or for obstructive vs. non-obstructive groups. Occurrence of arrhythmias during functional assessment was higher among younger adults (5.42% vs. 1.69% in older adults, p < 0.001). Twenty-three publications (9145 patients) evaluated the prognostic value of exercise capacity. There were 8.5% total deaths, 6.7% cardiovascular deaths, 3.0% sudden cardiac deaths (SCD), 1.2% heart failure death, 0.6% resuscitated cardiac arrests, 1.1% transplants, 2.6% implantable cardioverter defibrillator (ICD) therapies and 1.2 strokes (mean follow-up: 3.81 ± 2.77 years). VO2max, ATVO2, METs, % of age-gender predicted VO2max, % of age-gender predicted METs, ABPRE and ventricular arrhythmias were significantly associated with major outcomes individually. Mean VO2max was reduced in patients who reached the combined cardiovascular death outcome compared to those who survived (-6.20 mL·kg^-1·min^-1; CI 95%: -7.95, -4.46; p < 0.01).

CONCLUSIONS

CPET is a valuable tool and can safely perform for assessment of physical functional capacity in patients with HCM. VO2max is the most common performance measurement evaluated in functional studies, showing higher values in those based on cycle-ergometer compared to treadmill. Subgroup analysis shows that exercise intolerance seems to be more related to age, medication and comorbidities than HCM phenotype itself. Lower VO2max is consistently seen in HCM patients at major cardiovascular risk.

Hypertrophic Cardiomyopathy: Updates Through the Lens of Sports Cardiology

Purpose of review

This review will summarize the distinction between hypertrophic cardiomyopathy (HCM) and exercise-induced cardiac remodeling (EICR), describe treatments of particular relevance to athletes with HCM, and highlight the evolution of recommendations for exercise and competitive sport participation relevant to individuals with HCM.

Recent findings

Whereas prior guidelines have excluded individuals with HCM from more than mild-intensity exercise, recent data show that moderate-intensity exercise improves functional capacity and indices of cardiac function and continuation of competitive sports may not be associated with worse outcomes. Moreover, recent studies of athletes with implantable cardioverter defibrillators (ICDs) demonstrated a safer profile than previously understood. In this context, the updated American Heart Association/American College of Cardiology (AHA/ACC) and European Society of Cardiology (ESC) HCM guidelines have increased focus on shared decision-making and liberalized restrictions on exercise and sport participation among individuals with HCM.

Summary

New data demonstrating the safety of exercise in individuals with HCM and in athletes with ICDs, in addition to a focus on shared decision-making, have led to the most updated guidelines easing restrictions on exercise and competitive athletics in this population. Further athlete-specific studies of HCM, especially in the context of emerging therapies such as mavacamten, are important to inform accurate risk stratification and eligibility recommendations.

Impact of body mass index on left atrial dimension in HOCM patients

Background

Substantial studies have demonstrated that left atrial (LA) enlargement was a robust predictor of atrial fibrillation (AF) and obesity was a modifiable risk factor for cardiovascular diseases. However, the role of body mass index (BMI) on LA dimension in hypertrophic obstructive cardiomyopathy (HOCM) remains unclear.

Methods

A total of 423 HOCM patients (average BMI 25.4 ± 3.4 kg/m²) were recruited for our study. Participants were stratified into three groups based on BMI: normal weight (BMI < 23 kg/m²), overweight (BMI 23–27.5 kg/m²), and obesity (BMI ≥ 27.5 kg/m²).

Results

Compared with normal weight, patients with obesity had significantly lower prevalence of syncope (p = 0.007) and moderate or severe mitral regurgitation (p = 0.014), and serum NT-proBNP (p = 0.004). Multiple linear regression analysis indicated that BMI (β = 0.328, p < 0.001), log NT-proBNP (β = 0.308, p < 0.001), presence of AF (β = 0.209, p = 0.001), and left ventricular diastolic diameter index (β = 0.142, p = 0.019) were independently related with LA diameter. However, BMI was not an independent predictor of the presence of AF on multivariable binary logistical regression analysis.

Conclusions

BMI was independently associated with LA diameter; however, it was not an independent predictor of prevalence of AF. These results suggest that BMI may promote incidence of AF through LA enlargement in HOCM.

Machine Learning Methods for Identifying Atrial Fibrillation Cases and Their Predictors in Patients With Hypertrophic Cardiomyopathy: The HCM-AF-Risk Model

Background

Hypertrophic cardiomyopathy (HCM) patients have a high incidence of atrial fibrillation (AF) and increased stroke risk, even with low CHA₂DS₂-VASc (congestive heart failure, hypertension, age diabetes, previous stroke/transient ischemic attack) scores. Hence, there is a need to understand the pathophysiology of AF/stroke in HCM. In this retrospective study, we develop and apply a data-driven, machine learning–based method to identify AF cases, and clinical/imaging features associated with AF, using electronic health record data.

Methods

HCM patients with documented paroxysmal/persistent/permanent AF (n = 191) were considered AF cases, and the remaining patients in sinus rhythm (n = 640) were tagged as No-AF. We evaluated 93 clinical variables; the most informative variables useful for distinguishing AF from No-AF cases were selected based on the 2-sample t test and the information gain criterion.

Results

We identified 18 highly informative variables that are positively (n = 11) and negatively (n = 7) correlated with AF in HCM. Next, patient records were represented via these 18 variables. Data imbalance resulting from the relatively low number of AF cases was addressed via a combination of oversampling and undersampling strategies. We trained and tested multiple classifiers under this sampling approach, showing effective classification. Specifically, an ensemble of logistic regression and naïve Bayes classifiers, trained based on the 18 variables and corrected for data imbalance, proved most effective for separating AF from No-AF cases (sensitivity = 0.74, specificity = 0.70, C-index = 0.80).

Conclusions

Our model (HCM-AF-Risk Model) is the first machine learning–based method for identification of AF cases in HCM. This model demonstrates good performance, addresses data imbalance, and suggests that AF is associated with a more severe cardiac HCM phenotype.

The predictive value of epicardial adipose tissue volume assessed by cardiac magnetic resonance for atrial fibrillation in patients with hypertrophic obstructive cardiomyopathy

Atrial fibrillation (AF) is the most common arrhythmia and potentially increase the risk of embolic stroke and aggravate progressive heart failure in patients with hypertrophic cardiomyopathy (HCM). Recent studies demonstrated that epicardial adipose tissue (EAT) was closely associated with AF in general population. However, the relationship between EAT and AF in HCM patients remains unclear. A total of 93 consecutive patients with hypertrophic obstructive cardiomyopathy (HOCM) at Fuwai Hospital were enrolled in our study. There were 18 patients with AF and 75 patients without it. Cardiac magnetic resonance (CMR) imaging was performed in all participants. EAT volume (EATV) and left atrial volume (LAV) were determined by E-3D medical model software. HOCM patients with AF had significantly greater EATV index (EATVI, P < 0.001), LAV index (LAVI, P < 0.001) and left ventricular end-systole volume index (LVESVI, P = 0.039), and lower left ventricular ejection fraction (LVEF, P = 0.002). In multivariable logistic regression analysis, EATVI, LAVI, and LVEF remained independent determinants of AF occurrence (OR = 1.023, 95% CI, 1.003-1.043, P = 0.023, OR = 1.043, 95% CI, 1.012-1.075, P = 0.006, and OR = 0.887, 95% CI, 0.818-0.962, P = 0.004, respectively). Furthermore, receiver operating characteristic (ROC) curve analysis demonstrated that integration of EATVI, LAVI and LVEF provided better discriminatory performance for incident AF in HOCM patients with a high sensitivity of 94.4% and a specificity of 69.3% (AUC = 0.864, 95% CI, 0.771-0.958, P < 0.001). EATVI is an independent predictor of the presence of AF, and integration of EATVI, LVEF and LAVI determined by CMR provide greater discriminatory performance for identifying AF in HOCM patients.

Exercise and hypertrophic cardiomyopathy: Two incompatible entities?

A greater understanding of the pathogenic mechanisms underpinning hypertrophic cardiomyopathy (HCM) has translated to improved medical care and better survival of affected individuals. Historically these patients were considered to be at high risk of sudden cardiac death (SCD) during exercise; therefore, exercise recommendations were highly conservative and promoted a sedentary life style. There is emerging evidence that suggests that exercise in HCM has a favorable effect on cardiovascular remodeling and moderate exercise programs have not raised any safety concerns. Furthermore, individuals with HCM have a similar burden of atherosclerotic risk factors as the general population in whom exercise has been associated with a reduction in myocardial infarction, stroke, and heart failure, especially among those with a high-risk burden. Small studies revealed that athletes who choose to continue with regular competition do not demonstrate adverse outcomes when compared to those who discontinue sport, and active individuals implanted with an implantable cardioverter defibrillator do not have an increased risk of appropriate shocks or other adverse events. The recently published exercise recommendations from the European Association for Preventative Cardiology account for more contemporary evidence and adopt a more liberal stance regarding competitive and high intensity sport in individuals with low-risk HCM. This review addresses the issue of exercise in individuals with HCM, and explores current evidence supporting safety of exercise in HCM, potential caveats, and areas of further research.

How Will Genetics Inform the Clinical Care of Atrial Fibrillation?

Susceptibility to atrial fibrillation (AF) is determined by well-recognized risk factors such as diabetes mellitus or hypertension, emerging risk factors such as sleep apnea or inflammation, and increasingly well-defined genetic variants. As discussed in detail in a companion article in this series, studies in families and in large populations have identified multiple genetic loci, specific genes, and specific variants increasing susceptibility to AF. Since it is becoming increasingly inexpensive to obtain genotype data and indeed whole genome sequence data, the question then becomes to define whether using emerging new genetics knowledge can improve care for patients both before and after development of AF. Examples of improvements in care could include identifying patients at increased risk for AF (and thus deploying increased surveillance or even low-risk preventive therapies should these be available), identifying patient subsets in whom specific therapies are likely to be effective or ineffective or in whom the driving biology could motivate the development of new mechanism-based therapies or identifying an underlying susceptibility to comorbid cardiovascular disease. While current guidelines for the care of patients with AF do not recommend routine genetic testing, this rapidly increasing knowledge base suggests that testing may now or soon have a place in the management of select patients. The opportunity is to generate, validate, and deploy clinical predictors (including family history) of AF risk, to assess the utility of incorporating genomic variants into those predictors, and to identify and validate interventions such as wearable or implantable device-based monitoring ultimately to intervene in patients with AF before they present with catastrophic complications like heart failure or stroke.

Impacts of sinus rhythm maintenance with catheter ablation on exercise tolerance in patients with paroxysmal atrial fibrillation

BACKGROUND

It has been recently reported that sinus rhythm (SR) maintenance with catheter ablation therapy improves exercise tolerance (ET) in patients with persistent atrial fibrillation (AF). However, it remains to be elucidated whether this is also the case for patients with paroxysmal AF (PAF).

METHODS

We enrolled consecutive 54 patients with PAF (age; 63 ± 10 [SD] years old, male/female 46/8) and 26 patients with persistent AF (non-PAF) (age; 57 ± 12 [SD] years old, male/female 23/3) who underwent AF ablation without recurrence. ET and cardiac function were evaluated by cardio-pulmonary exercise test and ultrasound echocardiography before and 6 months after ablation.

RESULTS

The parameters of cardiopulmonary exercise test were comparable between the 2 groups. When PAF group was divided into 2 groups according to the time since diagnosis, peak oxygen uptake (peak VO₂) before ablation was significantly lower in patients with PAF duration of more than 1 year (n = 26), compared with those with less than 1 year (n = 28) (18.1 ± 3.7 vs 21.3 ± 5.8 ml/kg/min, P = 0.022). At 6 months after SR maintenance without AF burden, peak VO₂ significantly improved in both PAF (19.8 ± 5.1 to 22.0 ± 4.8 ml/kg/min, P = 0.0001) and non-PAF (20.6 ± 3.9 to 23.4 ± 5.0 ml/kg/min, P < 0.01). Furthermore, the improvement rate of peak VO₂ after successful ablation had a highly significant inverse relationship with peak VO₂ at baseline in patients with PAF (r = - 0.48, P = 0.0003).

CONCLUSIONS

These results indicate that SR maintenance with ablation improves ET in patients with PAF, especially in those with reduced ET.

Efficacy of Combined Cox-Maze IV and Ventricular Septal Myectomy for Treatment of Atrial Fibrillation in Patients With Obstructive Hypertrophic Cardiomyopathy

Atrial fibrillation (AF) has important clinical consequences in hypertrophic cardiomyopathy (HC). Safety and efficacy of the Cox-Maze IV procedure (when combined with ventricular septal myectomy) in patients with obstructive HC and paroxysmal AF is largely unresolved. Records of 395 consecutive HC patients (age 55 ± 13 years) who underwent septal myectomy for heart failure symptoms between 2004 and 2015 were reviewed. Sixty-two patients also had concomitant complete biatrial Cox-Maze IV for a history of symptomatic paroxysmal AF (3.0 ± 3.6 episodes) combined with myectomy comprise the study cohort. Freedom from symptomatic AF recurrences after operation was assessed. Left ventricular outflow gradients were reduced from 81 ± 28 mm Hg preoperatively to 1.2 ± 6.8 mm Hg after operation. At most recent follow-up, 53 patients (85%) were asymptomatic or mildly symptomatic. Freedom from recurrent symptomatic AF after myectomy/Cox-Maze IV was: 85% (95% confidence interval [CI] 73, 92) at 1 year, 69% (95% CI 55, 79) at 3 years, and 64% (95% CI 48, 75) at 5 years, including 34 patients (54%) who have experienced no symptomatic AF episodes for up to 8.2 years following surgery. The only clinical predictor of recurrent AF over follow-up was preoperative transverse left atrial dimension ≥45 mm (p <0.01). In conclusion, biatrial Cox-Maze IV combined with septal myectomy is associated with favorable long-term freedom from symptomatic paroxysmal AF recurrence, as well as from obstructive heart failure symptoms. These data support myectomy/Cox-Maze as an effective management option for the subgroup of HC patients with symptomatic outflow obstruction and paroxysmal AF.

Incident Atrial Fibrillation Is Associated With MYH7 Sarcomeric Gene Variation in Hypertrophic Cardiomyopathy

Background Although atrial fibrillation (AF) is common in hypertrophic cardiomyopathy (HCM) patients, the relationship between genetic variation and AF has been poorly defined. Characterizing genetic subtypes of HCM and their associations with AF may help to improve personalized medical care. We aimed to investigate the link between sarcomeric gene variation and incident AF in HCM patients. Methods and Results Patients from the multinational Sarcomeric Human Cardiomyopathy Registry were followed for incident AF. Those with likely pathogenic or pathogenic variants in sarcomeric genes were included. The AF incidence was ascertained by review of medical records and electrocardiograms at each investigative site. One thousand forty adult HCM patients, without baseline AF and with likely pathogenic or pathogenic variation in either MYH7 (n=296), MYBPC3 (n=659), or thin filament genes (n=85), were included. Compared with patients with variation in other sarcomeric genes, those with MYH7 variants were younger on first clinical encounter at the Sarcomeric Human Cardiomyopathy Registry site and more likely to be probands than the MYBPC3 variants. During an average follow-up of 7.2 years, 198 incident AF events occurred. Patients with likely pathogenic or pathogenic mutations in MYH7 had the highest incidence of AF after adjusting for age, sex, proband status, left atrial size, maximal wall thickness, and peak pressure gradient (hazard ratio, 1.7; 95% CI, 1.1-2.6; P=0.009). Conclusions During a mean follow-up of 7.2 years, new-onset AF developed in 19% of HCM patients with sarcomeric mutations. Compared with other sarcomeric genes, patients with likely pathogenic or pathogenic variation in MYH7 had a higher rate of incident AF independent of clinical and echocardiographic factors.

Metabolic changes in hypertrophic cardiomyopathies: scientific update from the Working Group of Myocardial Function of the European Society of Cardiology

Disturbed metabolism as a consequence of obesity and diabetes may cause cardiac diseases (recently highlighted in the cardiovascular research spotlight issue on metabolic cardiomyopathies).¹ In turn, the metabolism of the heart may also be disturbed in genetic and acquired forms of hypertrophic cardiac disease. Herein, we provide an overview of recent insights on metabolic changes in genetic hypertrophic cardiomyopathy and discuss several therapies, which may be explored to target disturbed metabolism and prevent onset of cardiac hypertrophy.

This article is part of the Mini Review Series from the Varenna 2017 meeting of the Working Group of Myocardial Function of the European Society of Cardiology.

Atrial Fibrillation in Hypertrophic Cardiomyopathy: Diagnosis and Considerations for Management

Atrial fibrillation is common in hypertrophic cardiomyopathy with a prevalence of 22-32 %. The impact of atrial fibrillation on overall survival, left ventricular function, thromboembolic stroke and quality of life is crucial. This review enlightens incidence, pathophysiology, and clinical symptoms. Early recognition of atrial fibrillation is essential. Monitoring methods for early detection are described. Finally effective therapy options are discussed including oral anticoagulation and the role of interventional catheter-based ablation in the treatment of atrial fibrillation in HCM patients.

Clinical Profile and Consequences of Atrial Fibrillation in Hypertrophic Cardiomyopathy

Background:

Atrial fibrillation (AF), the most common sustained arrhythmia in hypertrophic cardiomyopathy (HCM), is capable of producing symptoms that impact quality of life and is associated with risk for embolic stroke. However, the influence of AF on clinical course and outcome in HCM remains incompletely resolved.

Methods:

Records of 1558 consecutive patients followed at the Tufts Medical Center Hypertrophic Cardiomyopathy Institute for 4.8±3.4 years (from 2004 to 2014) were accessed.

Results:

Of the 1558 patients with HCM, 304 (20%) had episodes of AF, of which 226 (74%) were confined to symptomatic paroxysmal AF (average, 5±5; range, 1 to >20), whereas 78 (26%) developed permanent AF, preceded by 7±6 paroxysmal AF episodes. At last evaluation, 277 patients (91%) are alive at 62±13 years of age, including 89% in New York Heart Association class I or II. No difference was found in outcome measures for patients with AF and age- and sex-matched patients with HCM without AF. Four percent of patients with AF died of HCM-related causes (n=11), with annual mortality 0.7%; mortality directly attributable to AF (thromboembolism without prophylactic anticoagulation) was 0.1% per year (n=2 patients). Patients were treated with antiarrhythmic drugs (most commonly amiodarone [n=103] or sotalol [n=78]) and AF catheter ablation (n=49) or the Maze procedure at surgical myectomy (n=72). Freedom from AF recurrence at 1 year was 44% for ablation patients and 75% with the Maze procedure ( P <0.001). Embolic events were less common with anticoagulation prophylaxis (4/233, 2%) than without (9/66, 14%) ( P <0.001).

Conclusions:

Transient symptomatic episodes of AF, often responsible for impaired quality of life, are unpredictable in frequency and timing, but amenable to effective contemporary treatments, and infrequently progress to permanent AF. AF is not a major contributor to heart failure morbidity or a cause of arrhythmic sudden death; when treated, it is associated with low disease-related mortality, no different than for patients without AF. AF is an uncommon primary cause of death in HCM virtually limited to embolic stroke, supporting a low threshold for initiating anticoagulation therapy.

Occurrence and Natural History of Clinically Silent Episodes of Atrial Fibrillation in Hypertrophic Cardiomyopathy

Overt symptomatic atrial fibrillation (AF) occurs in over 20% of patients with hypertrophic cardiomyopathy (HC) leading to impaired quality of life, loss of productivity, and the risk for embolic stroke. However, the overall burden presented by AF in the HC population is unresolved due to the unknown frequency of silent asymptomatic episodes that do not necessarily achieve clinical recognition but nevertheless may have important disease-related implications. Therefore, stored electrograms were analyzed retrospectively for AF in 75 consecutive patients with HC (without AF history) implanted with dual-chamber cardioverter-defibrillators. Patients were followed for 5.0 ± 4.1 years at the Tufts Medical Center HCM Institute; ages were 50 ± 15 years, and 55% were male. Implantable cardioverter-defibrillator interrogation in the 75 patients showed AF to be absent in 54 (72%), 18 (24%) had clinically silent AF episodes, and the remaining 3 (4%) without previous asymptomatic episodes developed symptomatic and clinically overt paroxysmal AF. Of the 18 patients with clinically silent AF, 8 developed symptomatic AF, 4.1 ± 1.5 years later. Nonfatal embolic stroke occurred in 1 patient associated with asymptomatic AF and without other risk factors. In conclusion, clinically silent AF appears to be common in HC, occurring in almost 25% of patients. Such asymptomatic episodes of AF have important future implications, including potential thromboembolic risk, and development of symptomatic and clinically overt AF requiring prophylactic anticoagulation.

Atrial fibrillation in hypertrophic cardiomyopathy: A turning point towards increased morbidity and mortality

BACKGROUND

Atrial fibrillation (AF) is the most common arrhythmic event in patients with hypertrophic cardiomyopathy (HCM). The aim of this study was to identify the clinical impact and prognostic significance of AF on a large cohort of patients with HCM.

METHODS

Echocardiographic and clinical correlates, risk factors for AF and thromboembolic stroke and the prognostic significance of AF were evaluated in 509 patients with an established diagnosis of HCM.

RESULTS

A total of 119 patients (23.4%) were diagnosed with AF during the index evaluation visit. AF patients had a higher prevalence of stroke and presented with worse functional impairment. Left atrial diameter (LA size) was a common independent predictor of the arrhythmia (OR: 2.2, 95% CI 1.6-3.3) and thromboembolic stroke (OR: 1.6, 95% CI 1.01-2.40). AF was an important risk factor for overall mortality (HR=3.4, 95% CI: 1.7-6.5), HCM-related mortality (HR=3.9, 95% CI: 1.8-8.2) and heart failure-related mortality (HR=6.0, 95% CI: 2.0-17.9), even after adjusting for statistically significant clinical and demographic risk factors. However, AF did not affect the risk for sudden death.

CONCLUSIONS

LA size is an independent predictor of both AF and thromboembolic stroke. Moreover, patients with AF, regardless of type, have significantly higher mortality rates than patients without AF.

Almanac 2015: atrial fibrillation research in Heart

Atrial fibrillation continues to attract interest in the cardiovascular community and in Heart. Over 60 original research and review papers published in Heart in 2014–2015 cover various aspects of atrial fibrillation, from associated conditions and precipitating factors to new approaches to management. Here, we provide an overview of articles on atrial fibrillation published in Heart in 2014–2015, highlighting new developments, emerging concepts and novel approaches to treatment.

Atrial and ventricular arrhythmias in hypertrophic cardiomyopathy

Hypertrophic cardiomyopathy (HCM) is an autosomal dominant disease caused by mutations in genes coding for cardiac sarcomeres. HCM is the most common inherited heart disease, with a prevalence of 0.2%. There are multiple genetic variants that cause pleomorphic clinical attributes and disease characterized by myocardial disarray and myocardial hypertrophy. Patients are at an increased risk of atrial and ventricular arrhythmias. Management of these arrhythmias is complex. Atrial fibrillation is associated with increased mortality and thromboembolism. Ventricular arrhythmias are life threatening and best treated with an implantable defibrillator.

Disruption of type 5 adenylyl cyclase prevents β-adrenergic receptor cardiomyopathy: a novel approach to β-adrenergic receptor blockade

β-Adrenergic receptor (β-AR) blockade is widely used to treat heart failure, since the adverse effects of chronic β-AR stimulation are central to the pathogenesis of this disease state. Transgenic (Tg) mice, where β-AR signaling is chronically enhanced by overexpression of cardiac β₂-ARs, is a surrogate for this mechanism, since these mice develop cardiomyopathy as reflected by reduced left ventricular (LV) function, increased fibrosis, apoptosis, and myocyte hypertrophy. We hypothesized that disruption of type 5 adenylyl cyclase (AC5), which is in the β-AR signaling pathway in the heart, but exerts only a minor β-AR blocking effect, could prevent the cardiomyopathy in β₂-AR Tg mice without the negative effects of full β-AR blockade. Accordingly, we mated β₂-AR Tg mice with AC5 knockout (KO) mice. The β₂-AR Tg × AC5 KO bigenic mice prevented the cardiomyopathy as reflected by improved LV ejection fraction, reduced apoptosis, fibrosis, and myocyte size and preserved exercise capacity. The rescue was not simply due to a β-blocking effect of AC5 KO, since neither baseline LV function nor the response to isoproterenol was diminished substantially compared with the negative inotropic effects of β-blockade. However, AC5 disruption in β₂-AR Tg activates the antioxidant, manganese superoxide dismutase, an important mechanism protecting the heart from cardiomyopathy. These results indicate that disruption of AC5 prevents the cardiomyopathy induced by chronically enhanced β-AR signaling in mice with overexpressed β₂-AR, potentially by enhancing resistance to oxidative stress and apoptosis, suggesting a novel, alternative approach to β-AR blockade.