Background: Myocardial fibrosis is a common postmortem finding among individuals with Sudden Cardiac Death (SCD). Numerous in vivo and in vitro studies have shown that increased galectin-3 (gal3) expression into the myocardium is associated with higher incidence of fibrosis. Although elevated gal3 expression is linked with myocardial fibrosis, its role in predicting the risk of SCD is unknown. Methods: We reviewed the clinical datasets and post-mortem examination of 221 subjects who had died suddenly. We examined myocardial pathology including the extent of cardiac hypertrophy, fibrosis, and the degree of coronary atherosclerosis in these subjects. In a select group of SCD subjects, we studied myocardial gal3 and periostin expression using immunohistochemistry. To further examine if a higher level of circulating gal3 can be detected preceding sudden death, we measured serum gal3 in a porcine model of subtotal coronary artery ligation which shows an increased tendency to develop lethal cardiac arrhythmias, including ventricular tachycardia or fibrillation. Results: Of the total 1314 human subjects screened, 12.7% had SCD. Comparison of age-matched SCD with non-SCD subjects showed that SCD groups had excessive myocardial fibrosis involving both the left ventricular free wall and interventricular septum. In pigs with subtotal coronary artery ligation and SCD, we detected significantly elevated circulating gal3 levels approximately 10 days preceding the SCD event. Immunohistochemistry showed increased myocardial gal3 and periostin expression in pigs that died suddenly, compared to the controls. Conclusion: Our study shows that increased gal3 is associated with a higher risk of myocardial fibrosis and the risk of SCD. This supports the importance of larger translational studies to target gal3 to prevent cardiac fibrosis and attenuate the risk of SCD.
Introduction: Sudden cardiac death (SCD) is responsible for approximately 380,000 deaths per year. One third of the patients dying of heart disease present with SCD as the first manifestation. There are limited data on the clinico-pathological determinants of SCD. Hypothesis: We hypothesized that, compared to overall deaths, silent coronary atherosclerosis and myocardial fibrosis could be associated with increased frequency of SCDs. Methods: We reviewed the post-mortem data registry from two tertiary care hospitals located at the Buffalo-Niagara Region. Of the 1,314 subjects that underwent comprehensive post-mortem analysis, we identified 187 subjects that died suddenly. For this initial pilot data analysis protocol, we compared the demographic, clinical, electrocardiographic and coronary vascular and myocardial histopathological characteristics of 109 subjects with sudden death vs. 34 age-matched controls with non-sudden death. Results: We found that, of the total 1,314 subjects screened, 14% had SCD. Comparison of age-matched SCD with non-SCD subjects (age in years, SCD: 60±14; non-SCD: 61±20) showed that SCD groups had larger cardiac size (heart weight in grams, SCD: 550±150; non-SCD: 480±117, P=0.03), increased wall thickness (posterior wall thickness in cm, SCD: 1.7±0.4; non-SCD: 1.5±0.2, P=0.01), but reduced LV function reported before the event (LV ejection fraction in %, SCD: 41±17; non-SCD: 58±9, P=0.007). In addition, SCD groups had higher frequency of coronary atherosclerosis (SCD, 76% vs., non-SCD, 52%, P=0.007), and myocardial fibrosis involving both left ventricular free wall (SCD, 47% vs., non-SCD, 26%, P=0.03), and interventricular septum (SCD, 29% vs., non-SCD, 3%, P=0.02). There were no differences on serum electrolytes, circulating biomarkers and the extent of right ventricular fibrosis. Conclusions: The subjects that died suddenly had larger cardiac size, reduced contractile function with myocardial interstitial fibrosis, and silent coronary atherosclerosis. Further studies are in progress to fully examine the clinico-pathological correlates of SCD in our longitudinal study cohorts.
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