Table 1.
Clinical characteristics of 391 LQT3 patients, event-free at age 1 year. Abbreviations: QTp: QT peak interval, LCSD: Left cardiac sympathetic denervation, ICD: Internal Cardiac Defibrillator. Information on the use of mexiletine and flecainide was not uniformly collected in Europe and Japan.
| Characteristics | US | Europe | Japan | missing | Total |
|---|---|---|---|---|---|
| No of Patients | 208 | 155 | 28 | - | 391 |
| Male, #(%) | 85(41) | 72(46) | 17(61) | - | 174(45) |
| Proband #(%) | 37(18) | 34(22) | 11(39) | - | 82(21) |
| Age at ECG, yr | 26±19 | 31±20 | 25±19 | 33 | 28±20 |
| ECG, mean±sd | |||||
| RR, msec | 865±240 | 896±206 | 946±213 | 33 | 884±225 |
| PR, msec | 159±36 | 162±28 | 165±30 | 84 | 161±33 |
| QRS, msec | 83±13 | 104±112 | 87±16 | 35 | 92±73 |
| QTp, msec | 353±78 | 362±70 | 387±81 | 36 | 359±75 |
| QT, msec | 442±87 | 443±84 | 473±89 | 35 | 445±86 |
| QTc, msec | 479±50 | 471±63 | 487±62 | 35 | 476±57 |
| QTc Males, msec | 487±52 | 475±60 | 487±69 | 9 | 482±57 |
| QTc Females, msec | 473±48 | 466±67 | 486±51 | 26 | 471±56 |
| Treatment, #(%) | |||||
| β-blockers | 77(38) | 31(21) | 3(11) | 8 | 111(29) |
| LCTSD | 1(0) | 5(3) | 0(0) | 3 | 6(2) |
| Pacemaker | 13(6) | 6(4) | 0(0) | 3 | 19(5) |
| ICD | 49(24) | 16(10) | 4(14) | - | 69(18) |
| Location, #(%) | |||||
| N-Terminus | 1(0) | 0(0) | 0(0) | - | 1(0) |
| Transmembrane | 77(37) | 77(50) | 15(54) | - | 169(43) |
| C-Term | 59(28) | 44(28) | 12(43) | - | 115(29) |
| Intra | 71(34) | 34(22) | 1(4) | - | 106(27) |
| Mutation Type, #(%) | |||||
| Missense | 153(74) | 147(95) | 22(79) | - | 322(82) |
| Deletions | 55(26) | 8(5) | 6(21) | - | 69(18) |
| E1784K | 47(23) | 10(6) | 12(43) | - | 69(18) |
| D1790G | 0(0) | 29(19) | 0(0) | - | 29(7) |
| First Cardiac Event | |||||
| Syncope | 51(25) | 28(18) | 7(25) | - | 86(22) |
| ACA | 4(2) | 3(2) | 0(0) | - | 7(2) |
| Sudden Cardiac Death | 19(9) | 6(4) | 0(0) | - | 25(6) |
| Ever Cardiac Events | |||||
| Syncope | 51(25) | 28(18) | 7(25) | 1 | 86(22) |
| ACA | 8(4) | 8(5) | 6(21) | - | 22(6) |
| Sudden Cardiac Death | 27(13) | 11(7) | 2(7) | 1 | 40(10) |
| Appropriate Shock | 4(2) | 0(0) | 1(4) | 1 | 5(1) |