**2. Clinical parameters**

Coronary disease is the main etiology of heart disease in Western countries and the major cause of heart failure and SCD.It is defined by the presence of significant coronary stenosis in a main coronary vessel or by the demonstration of previous MI.

Sudden death associated with CHD may occur in the acute context or months to years after MI. At least 50% of all SCDs due to CHD occur as a first clinical event and among subgroups of patients thought to be at relatively low risk for SCD [15].

SCD risk is associated with the conventional risk factors for coronary atherosclerosis [16] in‐ cluding obesity, smoking [17], genetic predisposition [18], [19], ECG pattern of LVH or LBBB, certain angiographic parameters or heart rate profile during exercise [20].

The rhythm most often recorded at the time of sudden cardiac arrest is VT or VF [21]. The pathophysiological mechanism underlying the arrhythmias can be variable and mul‐ tifactorial.

Transient factors may interact with a fixed substrate that, in ischemic heart disease, is attrib‐ uted to scar-based re-entry.

In chronic stage of CHD, the occurrence of SCD has an inverse relation with EF of left ven‐ tricle and, at present, this is the parameter most widely used to categorize "high risk" pa‐ tients for SCD.

Other factors that have been demonstrated to contribute to the risk for SCD after MI include the presence of non-sustained ventricular tachycardia (nsVT), inducible VT by EP testing [22] or symptomatic heart failure (HF). Premature ventricular complexes (PVC) predict an increased risk of SCD during long-term follow-up, especially if ≥ 10 PVC per hour. The pres‐ ence of frequent PVCs during or after exercise has been associated with greater risk for seri‐ ous cardiovascular events but not specifically SCD.

Several other parameters are considered predictors of sudden death, but all with low or moderate predictive values, whose sensitivity and specificity have not yet been studied in detail in large patient populations.

Different noninvasive exams that allow quantification of ischemia (cardiac SPECT) [23], characterization of longitudinal strain abnormalities (echocardiography) [24] or MI scar (Cardiac Magnetic Resonance ) [25], T wave alternant (ECG) or the presence and extent of sympathetic denervation(cardiac 123I-MIBG imaging) were used in order to improve risk stratification of sudden death in ischemic cardiomyopathy [26], [27].
