Ranking based on relative risk value of risk factors for sudden death in the national cohort, as recorded at last follow-up: sudden death/cardiac arrest individuals compared with survivors, values with (95% CI)
| Risk factor | Relative risk | Sensitivity | Specificity | Fisher’s exact test |
| ECG risk score >5 | 46.5 (6.6 to 331) | 97 (83 to 100) | 80 (71 to 88) | p<0.0001 |
| ECG 12-lead product ≥2.2 mV.s | 30.0 (4.2 to 214) | 96 (82 to 100) | 69 (58 to 78) | p<0.0001 |
| Z-score maxWT >4.5 | 9.9 (3.1 to 31.2) | 88 (69 to 98) | 69 (59 to 78) | p<0.0001 |
| Septal thickness ≥190% of normal | 7.9 (3.2 to 19.4) | 82 (63 to 94) | 76 (67 to 84) | p<0.0001 |
| ECG QRS amplitude sum ≥10 mV in limb leads | 7.8 (3.2 to 19.0) | 83 (65 to 94) | 75 (65 to 84) | p<0.0001 |
| Z-score maxWT >6.0 | 6.1 (3.2 to 11.6) | 56 (35 to 76) | 93 (86 to 97) | p<0.0001 |
| MaxWT ≥2 cm | 5.0 (2.1 to 12.4) | 83 (64 to 94) | 62 (51 to 72) | p<0.0001 |
| Septum-to-cavity ratio >0.50 | 5.0 (2.3 to 10.9) | 72 (51 to 88) | 76 (66 to 84) | p<0.0001 |
| ST segment depression >2 mm at rest | 3.8 (2.3 to 7.2) | 45 (27 to 64) | 92 (85 to 96) | p<0.0001 |
| MaxWT ≥3 cm | 2.3 (1.2 to 4.4) | 30 (14 to 50) | 88 (80 to 94) | p=0.034 |
| Risk factors with less complete data | ||||
| VT on Holter (n=99) | 9.1 (3.6 to 22.8) | 72 (47 to 90) | 89 (80 to 95) | p<0.0001 |
| VES on exercise test (n=80) | 7.4 (2.7 to 20.2) | 55 (23 to 83) | 93 (84 to 98) | p=0.0006 |
| LVOT gradient >50 mm Hg at rest (n=127) | 6.6 (4.0 to 11.0) | 33 (16 to 55) | 99 (95 to 100) | p<0.0001 |
| LVOT gradient >20 mm Hg at rest (n=127) | 3.7 (1.7 to 8.1) | 74 (54 to 89) | 64 (54 to 74) | p<0.0004 |
| ST depression on exercise (n=80) | 5.7 (1.9 to 17.4) | 64 (31 to 89) | 83 (71 to 90) | p=0.0035 |
| LA:Ao ratio ≥1.5 (n=111) | 3.0 (1.4 to 6.3) | 45 (23 to 68) | 84 (74 to 90) | p=0.013 |
| Pathological blood pressure on exercise test (n=80) | 3.5 (0.8 to 16.0) | 78 (40 to 97) | 53 (41 to 65) | p=0.15, n.s. |
| History of sudden death (in familial HCM n=77) | 1.2 (0.5 to 2.8) | 50 (25 to 75) | 55 (42 to 68) | p=0.78, n.s. |
| Cardiac syncope (n=96) | 0.7 (0.1 to 7.5) | 10 (0.3 to 45) | 85 (76 to 92) | p=1.0, n.s. |
La:Ao, left atrial-to-aorta diameter ratio; LVOT, left ventricular outflow tract; maxWT, maximum wall thickness; 12-lead product, 12-lead amplitude × duration product17; VES, ventricular ectopic beats (occurring at sinus rate >110/min); VT, ventricular tachycardia.