Comparison of left versus right atrial myocardium in patients with sinus rhythm or atrial fibrillation - an assessment of mitochondrial function and microRNA expression

Abstract

Several of the cellular alterations involved in atrial fibrillation (AF) may be linked to mitochondrial function and altered microRNA (miR) expression. A majority of studies on human myocardium involve right atrial (RA) tissue only. There are indications that AF may affect the two atria differentially. This study aimed to compare interatrial differences in mitochondrial respiration and miR expression in the RA versus left atrium (LA) within patients with sinus rhythm (SR) and AF. Thirty‐seven patients with AF (n = 21) or SR (n = 16), undergoing coronary artery bypass surgery and/or heart valve surgery, were included. Myocardial biopsies were obtained from RA and LA appendages. Mitochondrial respiration was assessed in situ in permeabilized myocardium. MiR array and real‐time quantitative polymerase chain reaction were performed to evaluate miR expression. Mitochondrial respiratory rates were similar in RA versus LA. Expression of miR‐100, ‐10b, ‐133a, ‐133b, ‐146a, ‐155, ‐199a‐5p, ‐208b, and ‐30b were different between the atria in both SR and AF patients. In contrast, differential expression was observed between RA versus LA for miR‐93 in patients with SR only, and for miR‐1, ‐125b, ‐142‐5p, ‐208a, and ‐92b within AF patients only. These results indicate that mitochondrial respiratory capacity is similar in the RA and LA of patients with SR and AF. Differences in miR expressional profiles are observed between the RA versus LA in both SR and AF, and several interatrial differences in miR expression diverge between SR and AF. These findings may contribute to the understanding of how AF pathophysiology may affect the two atria differently.

A MicroRNA-Transcription Factor Blueprint for Early Atrial Arrhythmogenic Remodeling

“…Consequently, our second goal was to study whether the expression of these and other AF-associated miRNAs (not revealed by microarray evaluation) could be altered in our porcine model. To this end, the expression of 11 miRNAs, selected on the basis of published reports [ 7 – 9 , 13 , 14 , 21 ] (and references wherein), was analyzed by qPCR in the LA from paced versus sham pigs ( Figure 3 ). Six miRNAs (miR-1, miR-10a-5p, miR-10b, miR-21, miR-29a, and miR-208a) showed a higher expression in paced as compared with nonpaced animals.…”

“…In the same way, the levels of miR-133 expression significantly downregulated in chronic AF [ 13 , 14 ] were unchanged in our model. Upregulation of miR-18b and miR-363 was found to be associated with chronic AF in patients [ 21 ], albeit these miRNAs were downregulated in paced pigs (see Table 1 ). Overall, it is tempting to speculate that the expression of the same set of AF-associated miRNAs can be up- or downregulated as a function of progression from paroxysmal to chronic AF.…”

MiR-34a, miR-21 and miR-23a as potential biomarkers for coronary artery disease: a pilot microarray study and confirmation in a 32 patient cohort

“… 38 The remaining miRNA of the five in this investigation is miR-106b. Although this miRNA, which is within the miR-106b/25 cluster, has so far only been linked to CAD, 46 it has been shown to be upregulated in the atria of atrial fibrillation patients compared with those with increased sinus rhythm 47 in hypertension-induced heart failure. 48 This miRNA is also downregulated during aging 49 and is a potential marker for various types of cancers.…”

Remodeling of Kv1.5 Channel in Right Atria from Han Chinese Patients with Atrial Fibrillation

“…Although the trigger and maintenance of AF were mainly in left atrium, right atrial appendage is more accessible for sampling than the left atrial (LA) appendage[ 4 , 16 , 17 ]. Because the majority of studies investigating human tissue are restricted to the RA only [ 18 ], collecting both right and left atrial appendages is difficult in clinics. Therefore, we hypothesized that the tissues from right atrial appendages have the same presentation as the tissues from left atrial appendages.…”