Table 3.

Potential Mechanistic Axes for Sudden Cardiac Arrest

Mechanism	Comment	Reference
Electrophysiological
Reentry	Most common mechanism. Multiple subtypes. Myocardial reentry related to scar; bundle branch reentry; rotors	(118,124)
Repolarization prolongation	Pathophysiology likely related to temporo-spatial dispersion. Long QT; Acute ischemia; potassium channel blockade; enhanced late sodium current.	(118,125)
Repolarization dispersion	Measured as T peak to T end; phase 2 reentry in ischemia or Brugada syndrome; T-wave area dispersion; microvolt T-wave alternans (TWA).	(76,126,127)
Triggered -Early After Depolarizations (EADs)	Long QT syndromes; Heart failure-related Enhanced late inward Na current (INa-L)	(128)
Triggered -Delayed After Depolarizations (DADs)	CPVT; Idiopathic OT and annular VPDs and VT	(129)
Wavebreak	Transition from organized circuits, foci to fibrillation	(89,130)
Myocardial Ischemia
Myocardium	Myocardial infarction; Myocardial ischemia	(6)
Coronary	Atherosclerosis and collaterals; Coronary dissection; Coronary artery spasm; Myocardial- arterial bridge	(131)
Inflammation	Coronary events; QT modulation.	(132)
Mechanical
Stretch	LV dysfunction; mitral valve prolapse; sleep apnea; left bundle branch block	(91,93)
Fibrosis/scar	Post infarct; NICM; HCM. Facilitates reentry, other rhythms	(87)
Dyssynchrony	Bundle branch may cause cardiomyopathy; predispose to SCA	(133)
Mechanical Disruption	Commotio cordis, Aortic dissection	(134)
Neurologic
Sympathetic stimulation	Stellate ganglion activity may precede ventricular arrhythmias; takotsubo syndrome.	(135,136)
Neural sprouting	Infarction can cause sympathetic nerve sprouting and excessive regional sympathetic innervation.	(135)
Regional Myocardial inhomogeneity (MIBG)	Regionally inhomogeneously denervated myocardium is Arrhythmogenic.	(137)
Cerebral Events	Known causes of Sudden death	(10,49)
Genetic	Monogenic disorders (LQTS, CPVT, Brugada, HCM, ARVC, etc); familial pattern of death in acute MI	(47)