CARDIOVASCULAR JOURNAL OF AFRICA • Volume 34, No 3, July/August 2023 AFRICA 135 sudden cardiac arrest were detected more often in patients with a larger scar size in both groups (p < 0.001) (Figs 4–6). It was observed that serious cardiac events were less often seen in patient with a mean scar mass of < 5.4–8.4%. On the contrary, patients who had experienced sudden cardiac arrest had a mean scar mass of 15.9% and patients with ventricular tachycardia had a mean scar mass of 9.8% (Table 1). It was also interesting that hospitalisation with decompensated heart failure was significantly more frequent in patients with a high scar mass, especially in ICM patients with a mean scar mass of 27.9%. This may be explained that the scar mass in ICM patients was directly reflecting the severity of the baseline coronary artery disease and the number of territories involved. Another finding that may support this theory is that the mean LVEF for those patients was < 45%. Neilan et al.9 demonstrated that for every 1% of left ventricular mass increase in scar size, the risk of cardiovascular death or ventricular arrhythmia increased by 15%. This relationship was similar whether scar size was measured using the 2-SD method [hazard ratio (HR) 1.15; 95% confidence interval (CI): 1.12–1.18] or the FWHM method (HR 1.16; 95% CI: 1.12–1.20). When only arrhythmic events were considered, the extent of the scar was again associated with higher event risk (HR 1.17 for each 1% absolute increase in scar size; 95% CI: 1.12–1.22). Similar results were reported by Gulati et al.,10 where for each percentage scar extent, the risk of all-cause mortality was increased by 11% (HR 1.11; 95% CI: 1.06–1.16) and the risk for arrhythmic events was increased by 10% (HR 1.10; 95% CI: 1.05–1.16). Li et al.11 aimed to develop a risk score [LGE-based prediction of sudden cardiac death (SCD) risk in non-ischaemic dilated cardiomyopathy (NIDCM) (ESTIMATED)] based on LGE in CMR to predict SCD in patients with NIDCM and LVEF ≤ 35%. They followed up 395 patients with NIDCM for three years for SCD events. The estimated score (constructed by the LGE extent > 14%, syncope, atrial flutter/fibrillation, non-sustained ventricular tachycardia, advanced atrioventricular block, and age ≤ 20 or > 50 years) showed good calibrations for SCD prediction.11 From the score, 20.3% of primary-prevention patients were categorised as high risk (≥ three points), 28.1% as intermediate risk (two points) and 51.6% as low risk (zero to one point) for three-year SCD events (45.9 vs 20.1 vs 5.1%, p < 0.0001). The three-year SCD events were also well in agreement with the score stratification in patients without ICDs.11 Their study suggested LGE-based (ESTIMATED) risk score to be validated in providing refined SCD prediction. The score may help to identify candidates for primary-prevention ICDs in patients with NIDCM.11 80 70 60 50 40 30 20 10 0 % of scar Event severity 1 2 3 4 5 6 7 rs = 0.468* p < 0.001* 80 70 60 50 40 30 20 10 0 % of scar Event severity 1 2 3 4 5 6 7 rs = 0.558* p < 0.001* 80 70 60 50 40 30 20 10 0 % of scar Asympt CP HF HA Syncope VT Arrest Event * 80 60 40 20 0 % of scar Asympt CP HF HA Syncope VT Arrest Event * * ** ** * * Fig. 2. Relationship between event severity and scar percentage; A and C for group I, and B and D for group II. Asympt, asymptomatic; CP, chest pain; HF, heart failure; HA, hospitalisation; VT, ventricular tachycardia. A C B D
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