Sudden cardiac death (SCD) accounts for approximately 20% of all mortality in the western world, having an enormous impact on the socioeconomics. The challenge is to identify markers of SCD in high risk patients and in the general population so that it rate can be reduced to the minimum. It is well appreciated that etiological mechanisms of SCD are age-dependent and disease-specific, and are linked to ethnicity and affected by gender. Atherosclerotic coronary heart disease (ASHD) is the most frequent underlying disease in people over 35 years of age. There are various methods of risk stratification, but none appears to be specific enough to be generally applicable. These methods include cardiac function, heart rate variability, QT interval, QRS duration, 24-hour Holter recordings, baroreflex testing, electrophysiological study, etc..
Advances in molecular genetics in the past decade have conferred a new paradigm for the diagnosis of a variety of inherited structural heart diseases and malignant arrhythmogenic disorders causing SCD. In the former, hypertrophic cardiomyopathy, arrhythmogenic right ventricular dysplasia/cardiomyopathy and dilated cardiomyopathy are most commonly encountered. In the latter, congenital long QT syndrome, Brugada syndrome, catecholaminergic polymorphic ventricular tachycardia and short QT syndrome are identified. Collectively, these inherited arrhythmogenic disorders are called “ion channelopathies” Of note, risk of SCD in these inherited diseases appears to be relatively gene- and even mutation-specific. Although, up to date, no genetic markers of SCD can be demonstrated in patients with ASHD and congestive heart failure, postmortem molecular studies have unveiled certain gene variants or polymorphisms that might be responsible for the difference in the rate of SCD related to gender and ethnicity.
In conclusion, risk stratification for SCD should be individualized, taking multiple variables into consideration. Clinical skills and judgment remain essential.
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