Semi-quantitative versus quantitative assessments of late gadolinium enhancement extent for predicting spontaneous ventricular tachyarrhythmia events in patients with hypertrophic cardiomyopathy

Extent of late gadolinium enhancement (LGE) quantified by cardiac magnetic resonance was reportedly helpful for predicting the risk of ventricular tachyarrhythmias (VTA) in hypertrophic cardiomyopathy (HCM) patients. However, only a few data exist on the clinical implication of semi-quantitative assessment LGE extent in this patient population. The extent of left ventricular (LV) LGE was measured in 310 consecutive HCM patients using semi-quantitative (summing the LV segments with LGE, spatial extent) and quantitative (calculating the LGE volume percentage [vol% of LGE] against the total LV myocardial volume) methods, respectively. LV LGE was detected in 255 (82%) patients, most frequently in the mid-LV septum (n = 160, 52%). During the 49 ± 45 month follow-up, spontaneous VTA events were observed in 48 patients (16%) including aborted sudden cardiac death (SCD), appropriate defibrillator shock, and non-sustained VTA. The extent of LGE assessed by the two different methods showed a strong positive correlation (Spearman's r = 0.63, P < 0.001). Moreover, there was a graded increase in the rates of VTA with the LGE extent evaluated semi-quantitatively and quantitatively. The extent of LGE was identified as an independent predictor of VTA events and more extensive LGE (positive ≥ 4 segments) significantly raised the risk of VTA, irrespective of the presence of conventional risk factors for SCD including family history, unexplained syncope, LV wall thickness ≥30 mm. The extent of LGE, whether assessed by semi-quantitative or quantitative methods, was closely associated with an increased risk of spontaneous VTA events in HCM patients.