Dextrocardia: When right is wrong!

Introduction/background: Dextrocardia is a malposition of the heart in the thoracic cavity. Dextrocardia has been known to cause diagnostic dilemmas with atypical presentations in acute coronary syndrome, as well as technical challenges in patients who require interventions such as coronary catheterization, transcutaneous aortic valve replacement, ablation for arrhythmias, or pacemaker/defibrillator placement. Transcription factor Pitx2 has been shown to have a fundamental role during cardio-genesis, and its misexpression has been implicated in arrhythmogenesis and congenital heart diseases including visceral situs inversus. This association between congenital heart diseases and arrythmias is intriguing and need exploring. We aimed to quantify the likelihood of arrhythmias in patients with dextrocardia.

Materials And Methods: A descriptive, retrospective study was conducted on the National Inpatient Sample (NIS) databases for the year 2016. Patients with dextrocardia and arrhythmias were selected based on appropriate diagnostic codes. We used propensity score-matching to assemble a matched cohort in which adults with dextrocardia and controls balanced on measured baseline characteristics. This was done to reduce the confounding effect of between-group imbalances on outcomes. Complex survey design, weights, and clustering were accounted for during analysis. Multivariate regression analysis was performed to determine the relationship of arrhythmias and length of hospitalization with dextrocardia.

Results: The prevalence of arrhythmias in patients with dextrocardia was significantly higher than the control group. Overall, the odds of arrhythmia were higher for patients in the dextrocardia group when compared to a propensity matched control group [adjusted Odds ratio OR 2.60, Confidence Interval (CI) (1.67-4.06), p<0.001]. When looking at only principal/primary diagnosis on admission, the odds of an admitting diagnosis of arrhythmia were significantly higher in the dextrocardia group when compared to the matched cohort [adjusted OR 3.70, CI (1.26-10.89), p 0.02]. The increased odds of arrhythmia in dextrocardia patients were mostly accounted for by the increased odds of atrial fibrillation/atrial flutter [OR 3.06, CI (1.02-9.18), p 0.046] in these patients. No significant difference was found in the odds of other arrhythmias or the length of stay between the two groups.

Conclusion: In a large inpatient population, patients with dextrocardia were more likely to have arrhythmias especially atrial fibrillation/atrial flutter than patients without dextrocardia. Ours is the first study that investigates the clinical manifestations of molecular and embryologic associations between congenital heart disease and arrhythmias.