Sudden cardiac death is a complex phenomenon where the interaction of a transient trigger, such as an acute change in systolic blood pressure, with a pre-existing substrate induces lethal arrhythmias.
Sudden cardiac death remains a condition with an unacceptably high mortality. 1Indeed, while conscious patients without a previous resuscitation presenting with acute coronary syndromes have a very low hospital mortality between 2% and 5%, 2 in patients experiencing sudden cardiac death or cardiogeneic shock mortality increases up to 40% 3 and up to 10% experience brain damage. 4The reasons are multifactorial, but include unattended sudden cardiac death, late or inappropriate cardio-pulmonary resuscitation, and late arrival in the catheterization laboratory 5 for those in which an acute coronary syndrome is the underlying cause.Thus, a better understanding of the causes, early signs, and management of these patients is a truly unmet need.In his review article summarizing the ESC Rene ´Laennec lecture, 'Sudden cardiac death: the pro-arrythmic interaction of an acute loading with an underlying substrate' George Sutherland from the KU Leuven in Belgium addresses this issue. 6He reminds us that sudden cardiac death is a complex phenomenon, occurring either in apparently normal individuals or in those with a known underlying cardiac abnormality.In both groups, the lethal arrhythmia is commonly related to the physiological trigger of either exercise or stress.Previous research has focused on identifying vulnerable myocardial substrates, on pharmacological approaches to altering electrical activation or repolarization, 7 or on the suppression of induced lethal arrhythmias with defibrillators. 8However, in a significant number of cases, the interaction of a transient trigger with a pre-existing electrical or mechanical substrate, such as a scar, 9 is the basis for the lethal arrhythmia.An acute change in systolic blood pressure can induce a sequence of events in global and local cardiac mechanics which result in regional left ventricular post-systolic deformation which, mediated through stretch-induced changes in local mechano-electrical coupling, provokes local electrical afterdepolarizations.These then can induce runs of premature ventricular beats.These local acute pressure-and/or stretch-induced runs typically originate in either basal or apical myocardium and, in combination with a co-existing distal proarrhymic substrate, can interact to induce a lethal arrhythmia.Besides ischaemia, cardiomyopathies, 10 and muscle diseases, 11 channelopathies are a rare, but important cause of fatal arrhythmias.
Thomas F. Lüscher (Sat,) conducted a editorial in Sudden cardiac death. Sudden cardiac death is a complex phenomenon where the interaction of a transient trigger, such as an acute change in systolic blood pressure, with a pre-existing substrate induces lethal arrhythmias.