Mayank Sardana

Atrial fibrillation, cognition and dementia: A review

Atrial fibrillation (AF) is one of the most common types of cardiac arrhythmia, particularly among older adults. AF confers a 5‐fold risk for thromboembolic stroke as well as a 2‐fold higher risk for congestive heart failure, morbidity, and mortality. Although stroke remains an important and impactful complication of AF, recent studies have shown that AF is independently associated with other neurological disorders, including cognitive impairment and dementia, even after adjusting for prior ischemic stroke. We performed a review of the published literature on the association between AF and cognitive status. Further, we reviewed studies investigating the underlying mechanisms for this association and/or reporting the impact of AF treatment on cognitive function. While most published studies demonstrate associations between AF and impaired cognition, no AF treatment has yet been associated with a reduced incidence of cognitive decline or dementia.

Novel investigational therapies for treating pulmonary arterial hypertension

Introduction: Despite the development of new therapies, pulmonary arterial hypertension (PAH) has a median survival of 6 – 7 years. This is likely because the currently approved therapies affect predominantly pulmonary vasoconstriction. The past two decades have witnessed greater insights into the pathogenesis of PAH, from the role of inflammation to molecular signaling and epigenetics. Multiple pharmacological agents targeting these newly identified pathways are currently being investigated in preclinical and early clinical studies. Areas covered: Herein, the authors review the modalities targeting recently identified molecular targets in PAH. These include: prostaglandin receptor agonists, agents that alter the cyclic adenosine monophosphate and cyclic guanosine monophosphate pathways, vasoactive peptides, receptor tyrosine kinase inhibitors, Rho-kinase inhibitors, serotonin pathway inhibitors, anti-inflammatory agents, antioxidants, agents that alter nitric oxide signaling, various cardiac medications, mitochondrial metabolism modifying agents, epigenetic agents and cell-based therapies. The authors also address the gaps in the knowledge and explain why certain agents may or may not be promising PAH pharmacotherapeutics. Expert opinion: Newer agents target multiple pathways including vasoconstriction, cellular proliferation and inflammatory response. And while only a few of the current investigational drugs will likely be further developed, the authors expect that the next two decades will bring some major breakthroughs in PAH management.

Association of Left Atrial Function Index With Late Atrial Fibrillation Recurrence after Catheter Ablation.

Although catheter ablation (CA) for atrial fibrillation (AF) is commonly used to improve symptoms, AF recurrence is common and new tools are needed to better inform patient selection for CA. Left atrial function index (LAFI), an echocardiographic measure of atrial mechanical function, has shown promise as a noninvasive predictor of AF. We hypothesized that LAFI would relate to AF recurrence after CA.

Inactive Matrix Gla-Protein and Arterial Stiffness in Type 2 Diabetes Mellitus

BACKGROUND Large artery stiffness is increased in diabetes mellitus and causes an excessive pulsatile load to the heart and to the microvasculature. The identification of pathways related to arterial stiffness may provide novel therapeutic targets to ameliorate arterial stiffness in diabetes. Matrix Gla-Protein (MGP) is an inhibitor of vascular calcification. Activation of MGP is vitamin K dependent. We hypothesized that levels of inactive MGP (dephospho-uncarboxylated MGP; dp-ucMGP) are related to arterial stiffness in type 2 diabetes. METHODS We enrolled a multiethnic cohort of 66 participants with type 2 diabetes. Carotid-femoral pulse wave velocity (CF-PWV) was measured with high-fidelity arterial tonometry (Sphygmocor Device). Dp-ucMGP was measured with ELISA (VitaK; The Netherlands). RESULTS The majority of the participants were middle-aged (62 ± 12 years), male (91%), and had a history of hypertension (82%). Average hemoglobin A1C was 7.2% (55 mmol/mol). Mean dp-ucMGP was 624 ± 638 pmol/l and mean CF-PWV was 11 ± 4 m/sec. In multivariable analyses, dp-ucMGP was independently related to African American ethnicity (&bgr; = −0.24, P = 0.005), warfarin use (&bgr; = 0.56, P < 0.001), and estimated glomerular filtration rate (eGFR, &bgr; = −0.32, P < 0.001). Dp-ucMGP predicted CF-PWV (&bgr; = 0.40, P = 0.011), even after adjustment for age, gender, ethnicity, mean arterial pressure, eGFR, and warfarin use. CONCLUSIONS In our cross-sectional analysis, circulating dp-ucMGP was independently associated with CF-PWV in type 2 diabetes. This suggests that deficient vitamin K-dependent activation of MGP may lead to large artery stiffening and could be targeted with vitamin K supplementation in the patients with diabetes.

Association of Left Atrial Function Index with Atrial Fibrillation and Cardiovascular Disease: The Framingham Offspring Study

Background Left atrial (LA) size, a marker of atrial structural remodeling, is associated with increased risk for atrial fibrillation (AF) and cardiovascular disease (CVD). LA function may also relate to AF and CVD, irrespective of LA structure. We tested the hypothesis that LA function index (LAFI), an echocardiographic index of LA structure and function, may better characterize adverse LA remodeling and predict incident AF and CVD than existing measures. Methods and Results In 1786 Framingham Offspring Study eighth examination participants (mean age, 66±9 years; 53% women), we related LA diameter and LAFI (derived from the LA emptying fraction, left ventricular outflow tract velocity time integral, and indexed maximal LA volume) to incidence of AF and CVD on follow‐up. Over a median follow‐up of 8.3 years (range, 7.5–9.1 years), 145 participants developed AF and 139 developed CVD. Mean LAFI was 34.5±12.7. In adjusted Cox regression models, lower LAFI was associated with higher risk of incident AF (hazard ratio=3.83, 95% confidence interval=2.23–6.59, lowest [Q1] compared with highest [Q4] LAFI quartile) and over 2‐fold higher risk of incident CVD (hazard ratio=2.20, 95% confidence interval=1.32–3.68, Q1 versus Q4). Addition of LAFI, indexed maximum LA volume, or LA diameter to prediction models for AF or CVD did not significantly improve model discrimination for either outcome. Conclusions In our prospective investigation of a moderate‐sized community‐based sample, LAFI, a composite measure of LA size and function, was associated with incident AF and CVD. Addition of LAFI to the risk prediction models for AF or CVD, however, did not significantly improve their performance.

Beta‐Blocker Use Is Associated With Impaired Left Atrial Function in Hypertension

Background Impaired left atrial (LA) mechanical function is present in hypertension and likely contributes to various complications, including atrial arrhythmias, stroke, and heart failure. Various antihypertensive drug classes exert differential effects on central hemodynamics and left ventricular function. However, little is known about their effects on LA function. Methods and Results We studied 212 subjects with hypertension and without heart failure or atrial fibrillation. LA strain was measured from cine steady‐state free‐precession cardiac MRI images using feature‐tracking algorithms. In multivariable models adjusted for age, sex, race, body mass index, blood pressure, diabetes mellitus, LA volume, left ventricular mass, and left ventricular ejection fraction, beta‐blocker use was associated with a lower total longitudinal strain (standardized β=−0.21; P=0.008), and lower LA expansion index (standardized β=−0.30; P<0.001), indicating impaired LA reservoir function. Beta‐blocker use was also associated with a lower positive strain (standardized β=−0.19; P=0.012) and early diastolic strain rate (standardized β=0.15; P=0.039), indicating impaired LA conduit function. Finally, beta‐blocker use was associated with a lower (less negative) late‐diastolic strain (standardized β=0.15; P=0.049), strain rate (standardized β=0.18; P=0.019), and a lower active LA emptying fraction (standardized β=−0.27; P<0.001), indicating impaired booster pump function. Use of other antihypertensive agents was not associated with LA function. Conclusions Beta‐blocker use is significantly associated with impaired LA function in hypertension. This association could underlie the increased risk of atrial fibrillation and stroke seen with the use of beta‐blockers (as opposed to other antihypertensive agents) demonstrated in recent trials.

PERFORMANCE AND USABILITY OF A NOVEL SMARTPHONE APPLICATION FOR ATRIAL FIBRILLATION DETECTION IN AN AMBULATORY POPULATION REFERRED FOR CARDIAC MONITORING

Background: Current mHealth solutions for atrial fibrillation (AF) surveillance rely on smartphone-ECG dyads which require hardware that may limit widespread use. We previously described the development of an AF detection application (app) that leverages out-of-the-box smartphone (standard camera) to acquire pulsatile time series recordings and analyze using novel algorithms. Our aim in this study is to examine adherence and ambulatory performance of this prescribed app.

Pharmacokinetic drug evaluation of selexipag for the treatment of pulmonary arterial hypertension

ABSTRACT Introduction: Management of pulmonary arterial hypertension (PAH) remains challenging even in the contemporary era. Intravenous prostacyclin therapy, while associated with decreased mortality, has practical limitations and requires significant lifestyle modifications. The recently approved long-acting oral IP prostacyclin receptor agonist for treatment of PAH, selexipag, is a non-prostanoid agent that vasodilates, impacts remodeling (anti-proliferative), reduces endothelial cell dysfunction, inhibits platelet aggregation (anti-thrombotic), and increases right heart inotropy. Areas covered: This review discusses the limitations of non-oral prostacyclin therapy for PAH and describes the factors which led to successful development of selexipag in in vitro and preclinical studies. We review the pharmacokinetics and pharmacodynamics of selexipag. We further discuss the methodology and results of phase II and III trials, which led to approval of selexipag for PAH management. Expert opinion: As compared to previously developed oral prostacyclins, selexipag has limited adverse effects despite similar or better efficacy. Its final place in the treatment paradigm is not yet clear but it does represent a significant advance in the area of oral PAH therapy.

Plasma MicroRNAs Relate to Atrial Fibrillation Recurrence after Catheter Ablation: Longitudinal Findings from the MiRhythm Study

Introduction: Genetic and transcriptomic factors play important roles as mediators of new-onset and recurrent atrial fibrillation (AF). MicroRNAs (miRNAs) regulate expression of gene networks involved in key aspects of atrial remodeling. Associations between circulating miRNAs and AF recurrence are unknown. We tested the hypothesis that cardiac miRNAs associated with electrical and structural remodeling predict recurrent AF rhythm in post-ablation patients. Methods: We quantified plasma expression of 86 cardiac miRNAs using RT-qPCR in 83 consenting participants undergoing ablation for AF. MiRNA expression was re-measured 1-month post-ablation in a subset of 43 of 83 study participants. Then all 83 patients were followed over a 12-month period for AF recurrence and plasma miRNA expression was compared between baseline and 1-month post-ablation and between those with and without an AF recurrence. Results: The mean age of study participants was 59 years, 34% were female, and 63% had paroxysmal AF. Plasma levels of miRNAs 125a-5p and 10b were 3-fold lower after ablation compared to pre-ablation (p<0.01). Pre-ablation plasma expression of miRNAs 125a and 10b, as well as miRNAs 60, 30a-3p and 199b, were higher among patients with an AF recurrence compared to those without recurrence after ablation (p<0.05) even after adjustment for clinical risk factors. Conclusion: The plasma miRnome is dynamic after AF ablation and associated with AF recurrence. Higher pre-ablation levels of circulating gene regulators implicated in atrial remodeling and AF, including miRNAs 125a-5p and 10b, were associated with AF recurrence and that these same miRNAs decreased post-ablation. Our investigation highlights dynamic gene regulatory networks in patients undergoing ablation and identifies potentially new AF treatment targets.

Indexed Left Atrial Adipose Tissue Area Is Associated With Severity of Atrial Fibrillation and Atrial Fibrillation Recurrence Among Patients Undergoing Catheter Ablation

Background: Epicardial adipose tissue (EAT) has been associated with adverse left atrial (LA) remodeling and atrial fibrillation (AF) outcomes, possibly because of paracrine signaling. Objectives: We examined factors associated with a novel measure of EAT i.e., indexed LAEAT (iLAEAT) and its prognostic significance after catheter ablation (CA) of atrial fibrillation (AF). Methods: We performed a retrospective analysis of 274 participants with AF referred for CA. LAEAT area was measured from a single pre-ablation CT image and indexed to body surface area (BSA) to calculate iLAEAT. Clinical, echocardiographic data and 1-year AF recurrence rates after CA were compared across tertiles of iLAEAT. We performed logistic regression analysis adjusting for factors associated with AF to examine relations between iLAEAT and AF recurrence. Results: Mean age of participants was 61 ± 10 years, 136 (49%) were women, mean BMI was 32 ± 9 kg/m2 and 85 (31%) had persistent AF. Mean iLAEAT was 0.82 ± 0.53 cm2/m2. Over 12-months, 109 (40%) had AF recurrence. Participants in the highest iLAEAT tertile were older, had higher CHA2DS2VASC scores, more likely to be male, have greater LA volume, and were more likely to have persistent (vs. paroxysmal) type AF than participants in the lowest iLAEAT tertile (p for all < 0.05). In regression analyses, iLAEAT was associated with higher odds of AF recurrence (OR = 2.93; 95% CI 1.34–6.43). Conclusions: iLAEAT can quantify LA adipose tissue burden using standard CT images. It is strongly associated with AF risk factors and outcomes, supporting the hypothesis that EAT plays a role in the pathophysiology of AF.