Nonatherosclerotic narrowing of the atrioventricular node artery and sudden death

This study was undertaken to determine whether thickening of the atrioventricular (AV) node artery is a cause of sudden cardiac death.

Thickening of the AV node artery has been implicated as a cause of sudden death primarily on the basis of case reports. Few pathologic studies have compared subjects who died of sudden cardiac death with normal control subjects who died traumatically.

The AV node artery in 27 patients with unexplained sudden cardiac death (mean age 24.8 +/- 7.4 years) was compared with that in 17 control subjects who died traumatically (mean age 25.6 +/- 7.0 years). No anatomic cause of death was found at autopsy in the subjects with sudden death, all of whom died of presumed cardiac arrhythmias. The conduction system of all hearts was studied by semiserial sections and Movat pentachrome stains. At the point of greatest narrowing of the AV node artery, the outer circumference and lumen outline were traced by computerized morphometry, the ratio of outer vessel area to lumen area was calculated and the histopathologic changes were noted.

The rank-sum of ratios was significantly greater in the sudden death group than in the control group (p = 0.031, Wilcoxon rank-sum/Mann-Whitney statistic). A dysplastic AV node artery with significant acid mucopolysaccharide deposition was seen almost exclusively in the sudden death group (12 of 27 vs. 1 of 17, p = 0.006). In 10 subjects with sudden death a dysplastic AV node artery was narrowed > 2 SD over the control value; half of this subgroup died during exercise and one third had a family history of sudden unexplained cardiac death.

Dysplasia of the AV node artery may contribute to death in a substantial portion of patients with unexplained sudden death, and such death is often associated with exercise and a family history of unexplained sudden death.