Suitability of new non-invasive predictors for combined risk assessment of sudden cardiac death in patients after myocardial infarction
The purpose of the study was to improve the risk prediction of SCD in post-MI patients by comparing the informative value of new non-invasive SCD risk stratification factors (HRT, mTWA, DC) with the well-known factors (impaired HRV, low left ventricular ejection fraction (LVEF), ventricular arrhythmias) both alone and in combination. Holter monitoring (HM) with evaluation of the above factors and echocardiography with LVEF measurement were performed in 111 patients (84 males and 27 females) aged 64.1 ±10.5 years who had MI from 2 months to 36 years (mean 27 [9; 84] months) prior to admission. The follow-up period was 12 months. The endpoints included SCD and overall cardiovascular mortality. During follow-up 15 cases of SCD and 8 other cardiovascular deaths (5 repeated fatal MI and 3 lethal strokes) were registered. LVEF was the most significant predictor of overall mortality followed by DC, HRT, HRV, mTWA and QRS width. LVEF turned out to be the most significant risk factor for SCD followed by HRT, QRS width, DC, number of PVCs per day and mTWA. Noninvasive electrophysiological predictors showed the maximum SCD predictive value in patients with LVEF >40%, whereas at lower LVEF their predictive value was either decreased or completely lost. Combined risk assessment revealed that combination of HRT2 and increased mTWA caused a significantly increased risk of cardiovascular death (OR 30.7 (95% CI, 3.5-271.6), p <0.001) and especially from SCD (OR 63.3 (95% CI, 6.8-585.8), p <0.001) compared to any other combination including those with reduced LVEF. Thus, the evaluation of HRT, DC and mTWA during HM enables to define the population of post-MI patients with high risks of cardiovascular mortality and SCD. These predictors are most effective in combination, as well as in patients with LVEF >40%. The combination of HRT2 and mTWA <sub>100</sub> >53 mcV is associated with a maximum increased risk of cardiovascular death and SCD.