Incremental Value of Right Atrial Strain Analysis to Predict Atrial Fibrillation Recurrence After Electrical Cardioversion

BACKGROUND

Although the assessment of left atrial (LA) mechanics has been reported to refine atrial fibrillation (AF) risk prediction, it doesn't completely predict AF recurrence. The potential added role of right atrial (RA) function in this setting is unknown. Accordingly, this study sought to evaluate the added value of RA longitudinal reservoir strain (RASr) for the prediction of AF recurrence after electrical cardioversion (ECV).

METHODS

We retrospectively studied 132 consecutive patients with persistent AF who underwent elective ECV. Complete two-dimensional and speckle-tracking echocardiography analyses of LA and RA size and function were obtained in all patients before ECV. The end point was AF recurrence.

RESULTS

During a 12-month follow-up, 63 patients (48%) showed AF recurrence. Both LASr and RASr were significantly lower in patients experiencing AF recurrence than in patients with persistent sinus rhythm (LASr, 10% ± 6% vs 13% ± 7%; RASr, 14% ± 10% vs 20% ± 9%, respectively; P < .001 for both). Right atrial longitudinal reservoir strain (area under the curve = 0.77; 95% CI, 0.69-0.84; P < .0001) was more strongly associated with the recurrence of AF after ECV than LASr (area under the curve = 0.69; 95% CI, 0.60-0.77; P < .0001). Kaplan-Meier curves showed that patients with both LASr ≤ 10% and RASr ≤ 15% had a significantly increased risk for AF recurrence (log-rank, P < .001). However, at multivariable Cox regression, RASr (hazard ratio, 3.26; 95% CI, 1.73-6.13; P < .001) was the only parameter independently associated with AF recurrence. Right atrial longitudinal reservoir strain was more strongly associated with the occurrence of AF relapse after ECV than LASr, and LA and RA volumes.

CONCLUSION

Right atrial longitudinal reservoir strain was independently and more strongly associated than LASr with AF recurrence after elective ECV. This study highlights the importance of assessing the functional remodeling of both the RA and LA in patients with persistent AF.

511 INCREMENTAL VALUE OF RIGHT ATRIAL STRAIN ANALYSIS TO PREDICT ATRIAL FIBRILLATION RECURRENCE AFTER CARDIOVERSION

Background

In patients with paroxysmal atrial fibrillation (AF), left atrial (LA) mechanics has been reported to be important to predict recurrences after cardioversion. However, the potential additive role of right atrial (RA) function in this setting remains to be tested. Accordingly, the aims of our study was to assess the added role of right atrial reservoir longitudinal strain (RARS) for prediction of AF recurrence after electrical cardioversion.

Methods

we prospectively studied 130 (mean age 69±14, 55% men) consecutive patients with persistent AF who underwent electrical cardioversion, acquired between June 2020 and December 2021. Exclusion criteria were: presence of pacemaker, more than moderate mitral and tricuspid regurgitation, left or right ventricular dysfunction, prior cardiac surgery, and, inadequate acoustic window. LA and RA 2D-speckle-tracking echocardiography analyses were obtained from dedicated, non-foreshortened 4-ch and RV-focused apical 4-ch views respectively, using a dedicated software package (AFI LA, EchoPAC 204, GE Vingmed, Horten, Norway). The primary endpoint was AF recurrence.

Results

after a follow-up period of 12 months, 60 patients (45%) reached the primary endpoint. The mean left ventricular ejection fraction (LVEF) was 56.5±8%, for all patients. No significant difference in LA (98±31 vs 94±30 mL, p= 0.333) and RA (68±26 vs 65±26 mL, p=0.286) volumes was detected between patients with and without AF recurrence, while left atrial reservoir strain (LARS, 10±6 vs 14±7%, p&lt;0.001) and RA reservoir strain (RARS, 14±10 vs 16±8%, p&lt;0.001) were significantly lower in patients with recurrent AF. Receiving operator characteristics curve analysis showed that the predictive power of LARS (AUC 0.68 [IC 95% 0.58-0.78]), was lower than RARS (AUC 0.75 [IC 95% 0.66-0.84]) (p&lt;0.001, for all), with cut-off of 10.5% (sensitivity 62%, specificity 70%) and, 15.5% (sensitivity 75%, specificity 75%), respectively. Kaplan-Meier curve for time to primary endpoint showed that patients with LARS≤10.5% and RARS ≤15.5% had a significant risk for AF recurrences (log rank,p&lt;0.001), even after correcting for confounding variables. However, at multivariable Cox regression RARS (HR 3.42 [CI 95% 1.72-6.8], p&lt; 0.001) was the only parameter independently associated with the primary endpoint.

Conclusions

RARS is an independent predictor of the recurrences of AF after electrical cardioversion and provides an incremental prognostic value over LARS. This study highlights the pivotal role of the assessment of bi-atrial remodeling in patients with AF.

Insulin/glucose induces natriuretic peptide clearance receptor in human adipocytes: a metabolic link with the cardiac natriuretic pathway

Cardiac natriuretic peptides (NP) are involved in cardiorenal regulation and in lipolysis. The NP activity is largely dependent on the ratio between the signaling receptor NPRA and the clearance receptor NPRC. Lipolysis increases when NPRC is reduced by starving or very-low-calorie diet. On the contrary, insulin is an antilipolytic hormone that increases sodium retention, suggesting a possible functional link with NP. We examined the insulin-mediated regulation of NP receptors in differentiated human adipocytes and tested the association of NP receptor expression in visceral adipose tissue (VAT) with metabolic profiles of patients undergoing renal surgery. Differentiated human adipocytes from VAT and Simpson-Golabi-Behmel Syndrome (SGBS) adipocyte cell line were treated with insulin in the presence of high-glucose or low-glucose media to study NP receptors and insulin/glucose-regulated pathways. Fasting blood samples and VAT samples were taken from patients on the day of renal surgery. We observed a potent insulin-mediated and glucose-dependent upregulation of NPRC, through the phosphatidylinositol 3-kinase pathway, associated with lower lipolysis in differentiated adipocytes. No effect was observed on NPRA. Low-glucose medium, used to simulate in vivo starving conditions, hampered the insulin effect on NPRC through modulation of insulin/glucose-regulated pathways, allowing atrial natriuretic peptide to induce lipolysis and thermogenic genes. An expression ratio in favor of NPRC in adipose tissue was associated with higher fasting insulinemia, HOMA-IR, and atherogenic lipid levels. Insulin/glucose-dependent NPRC induction in adipocytes might be a key factor linking hyperinsulinemia, metabolic syndrome, and higher blood pressure by reducing NP effects on adipocytes.

Hypokalemic rhabdomyolysis in a patient with a laparoscopic adjustable gastric banding

Rhabdomyolysis is an acute skeletal muscle disorder characterized by altered integrity of the cell membranes of muscle fiber cells. It can be related to a variety of factors: muscular trauma, muscle enzyme deficiencies, infections, drugs, toxins, alcohol ingestion, endocrinopathies and electrolyte imbalances such as hypokalemia. We report the case of a 46-year-old woman admitted to the Emergency Department for frequent episodes of vomiting associated with food intake in the last two weeks, general muscular weakness and myalgia. Physical examination on admission was unremarkable, except for a symmetrical and dominantly proximal muscular weakness of all four extremities. Blood pressure was 116/70 mmHg with a sinus bradycardia (53 beats/min) on the electrocardiogram. Laboratory tests showed a metabolic alkalosis with marked hypokalemia (K+= 1.9 mEq/l) and elevation of muscular enzymes (myglobin= 993 ng/ml, troponin T= 0,10 ng/ml e CK= 1113 U/l). No symptoms of recurrent rhabdomyolysis were reported, patient denied alcohol consumption and there was not clinical evidence of hyperthyroidism. A iatrogenic etiology could not be excluded for certain because patient was in therapy with lansoprazole (Naranjo algorithm 3/13) but, revealing medical history that she underwent a laparoscopic adjustable gastric banding for the treatment of a severe obesity, we focused our attention on hypokalemia, due to persistent vomiting. Fasting, administration of metoclopramide and infusion of potassium chloride resulted in steady improvement of clinical conditions and normalization of electrolyte imbalance. At the clinical follow-up of three months, after partial deflation of the gastric banding, the patient was asymptomatic with muscular enzymes and potassium levels in the normal range. Authors discuss the pathophysiologic mechanisms of these alterations.

Metformin-induced lactic acidosis in a type 2 diabetic patient with acute renal failure

Metformin is a biguanide commonly used in type 2 diabetes mellitus (DM). Lactic acidosis, a potentially life-threatening metabolic disorder, may be due to a number of different causes, including metformin therapy. We present a case of a severe metformin-induced lactic acidosis in a patient with type 2 DM, admitted to the emergency department with a history of dehydration due to diarrhoea and complicated by acute renal failure. Patient complained malaise and severe weakness and was tachypneic (Kussmaul's respiration), agitated and confused, with a Glasgow Coma Scale score of 13/15. Heart rate was 75 b/min and blood pressure 110/80 mmHg. The pH was 6.87, HCO3- 3 mmol/l, lactate 15 mmol/l, potassium 6.9 mEq/l. The renal function was markedly impaired with a creatinine of 9.75 mg/dl, and pancreatic enzymes, amylase and lipase, were also increased in absence of abdominal pain. Patient was treated with intravenous fluids, bicarbonate infusion and haemodialysis with bicarbonate buffered replacement fluid. Clinical conditions improved rapidly, with a progressive normalization of the acid-base balance and the other laboratory data. Authors discuss the pathophysiologic mechanisms of these alterations with particular regard to the role played by metformin as potential cause of lactic acidosis.

FokI polymorphism of the vitamin D receptor gene correlates with parameters of bone mass and turnover in a female population of the Italian island of Lampedusa

One of the most promising genetic approaches to dissecting a multifactorial disease is represented by genetically isolated population studies. We studied a genetic marker in a cohort of women living on the Mediterranean island of Lampedusa, a geographically isolated population. Lampedusa, located between the African coast and Sicily, consists of a young genetic isolate (<20 generations) with an exponential growth in the last generations. We analyzed the association between the FokI vitamin D receptor (VDR) gene polymorphism, previously proposed as a predictor of bone mass, with parameters of bone mass and turnover in a cohort of pre- and postmenopausal women living on Lampedusa. In 424 women (277 postmenopausal and 147 premenopausal), allelic frequencies were 49% for the F allele and 51% for the f allele. Using analysis of covariance, we found that subjects with ff genotype exhibited a significantly (P < 0.001) lower lumbar spine bone mass, by dual-energy X-ray absorptiometry, and lower values of bone ultrasonographic parameters (speed of sound and broadband ultrasound attenuation) relative to those with Ff and FF genotypes. Conversely, osteocalcin and serum cross-laps were significantly higher in ff and Ff compared to FF genotype. Our data suggest that FokI VDR polymorphism may contribute to the determination of bone mass and turnover in both pre- and postmenopausal women in this geographically isolated population.