Background Skin sympathetic nerve activity (SKNA) is useful in estimating sympathetic tone in humans Objective To test the hypothesis that (1) increased SKNA is associated with the onset and termination of paroxysmal atrial tachycardia (AT) and AF and (2) The sinoatrial node (SAN) response to SKNA is reduced in patients with more frequent of AT or AF. Methods SKNA and electrocardiogram were recorded in 11 patients (4 males and 7 females, average age 66±10 years), including 3 patients with AT (11±18 episodes/patient) and 8 patients with AF (24±26 episodes/patient). Results The average SKNA (aSKNA, in μV) 10 s prior to AT onset were 1.07±0.10; 10 s after termination were 1.27±0.10, both were significantly (p=0.032, p<0.0001) higher than that during sinus rhythm (0.97±0.09). The aSKNA 10 s prior to AF onset were 1.34±0.07 and 10 s after termination were 1.31±0.07. Both were significantly (p<0.0001) higher than that during sinus rhythm (1.04±0.07). The aSKNA before onset (p<0.0001) and after termination (p= 0.0011) were both higher in AF than in AT. The sinus rate correlated (p<0.0001) with aSKNA in each patient (average r: 0.74, 95% confidence interval (CI): 0.65–0.84). The r in each patient negatively correlated with the number of AT and AF episodes (r= − 0.6493, 95% confidence interval: −0.8990 to −0.08073, p=0.0306). Conclusions Increased SKNA was observed both at onset and termination of AT and AF. The patients with more frequent AT and AF episodes had less of a correlation between sinus rate and aSKNA, suggesting SAN remodeling by tachycardia.

BackgroundThe etiology of conduction disturbances necessitating permanent pacemaker (PPM) implantation is often unknown, although familial aggregation of PPM (faPPM) suggests a possible genetic basis. We developed a pan-cardiovascular next generation sequencing (NGS) panel to genetically characterize a selected cohort of faPPM.Materials and MethodsWe designed and validated a custom NGS panel targeting the coding and splicing regions of 246 genes with involvement in cardiac pathogenicity. We enrolled 112 PPM patients and selected nine (8%) with faPPM to be analyzed by NGS.ResultsOur NGS panel covers 95% of the intended target with an average of 229x read depth at a minimum of 15-fold depth, reaching a SNP true positive rate of 98%. The faPPM patients presented with isolated cardiac conduction disease (ICCD) or sick sinus syndrome (SSS) without overt structural heart disease or identifiable secondary etiology. Three patients (33.3%) had heterozygous deleterious variants previously reported in autosomal dominant cardiac diseases including CCD: LDB3 (p.D117N) and TRPM4 (p.G844D) variants in patient 4; TRPM4 (p.G844D) and ABCC9 (p.V734I) variants in patient 6; and SCN5A (p.T220I) and APOB (p.R3527Q) variants in patient 7.ConclusionFaPPM occurred in 8% of our PPM clinic population. The employment of massive parallel sequencing for a large selected panel of cardiovascular genes identified a high percentage (33.3%) of the faPPM patients with deleterious variants previously reported in autosomal dominant cardiac diseases, suggesting that genetic variants may play a role in faPPM.

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