Arrhythmic risk stratification in ischemic, non-ischemic and hypertrophic cardiomyopathy: A two-step multifactorial, electrophysiology study inclusive approach

Table 1 Abnormal values and connection of every non-invasive risk factors with the arrhythmogenic mechanisms

Non-invasive risk factors	Abnormal values	Mechanisms
SAECG, LPs	2/3 positive criteria	Fibrotic areas, slow conduction, reentry
QTc	≥ 440 ms (♂), ≥ 450 ms (♀)	Prolonged repolarization, EAD, DAD
TWA	≥ 65 μV (2-channels)	APD and Ca2+ alternans, steep APDR and CVR, steep FSRCR
VPBs	≥ 30/24 h	Automaticity (Ca2+oscillations), reentry
NSVT	≥ 1 episode/24 h	Automaticity (Ca2+oscillations), reentry
SDNN/HRV	≤ 75 ms	Enhanced sympathetic tone, autonomic imbalance
DC/HRT	DC ≤ 4.5 ms	Vagal and sympathetic ANS dysfunction
	HRT onset ≥ 0%
	HRT slope ≤ 2.5ms

ANS: Autonomic nervous system; APD: Action potential duration; APDR: Action potential duration restitution; CVR: Conduction velocity restitution; DAD: Delayed afterdepolarization; DC: Deceleration capacity from heart rate dynamics; EAD: Early afterdepolarization; FSRCR: Fractional sarcoplasmic reticulum Ca²⁺ release; HRT: Heart rate turbulence; LPs: Late potentials from signal-averaged electrocardiogram; NSVT: Non-sustained ventricular tachycardia; QTc: Corrected according to Fridericia formula QT interval; SAECG: Signal-averaged electrocardiogram; SDNN: Standard deviation of normal to normal beats from heart rate variability analysis; TWA: T wave alternans; VPBs: Ventricular premature beats.