Table 1.
Characteristics of the study population
| Characteristic | Men (n = 450) | Women (n = 601) | P |
|---|---|---|---|
| ECG parameters | |||
| Overall QTc (ms) | 473 ± 55 | 486 ± 55 | <.001 |
| Age ≤ 13 y | 486 ± 53 | 485 ± 54 | .21 |
| Age > 13 y | 460 ± 53 | 487 ± 56 | <.001 |
| QTc > 500 ms (%) | 22 | 27 | .09 |
| RR (ms) | 842 ± 220 | 837 ± 199 | .55 |
| Mutation location (%) | |||
| Cytoplasmic loop (S2–S3 or S4–S5 IDL) | 19 | 19 | .92 |
| MS | 53 | 54 | .67 |
| N/C terminus | 28 | 26 | .58 |
| Mutation type (%) | |||
| Missense | 83 | 79 | .13 |
| LQTS therapies during follow-up (%) | |||
| Beta-blockers | 45 | 46 | .74 |
| Pacemaker | 1.6 | 1.5 | .94 |
| ICD | 4 | 9 | .003 |
| LCSD | 1.1 | 0.5 | .30 |
| Cardiac events during follow-up (%) | |||
| Syncope | 35 | 36 | .84 |
| ACA | 3 | 4 | .22 |
| SCD | 13 | 8 | .007 |
| Appropriate ICD shocks | 0.2 | 1.7 | .03 |
| ACA or SCD* | 15 | 11 | .07 |
Values are mean ± SD unless otherwise indicated.
ACA = aborted cardiac arrest; ECG = electrocardiogram; ICD = implantable cardioverter defibrillator; LCSD = left cervical sympathetic denervation; LQTS = long QT syndrome; MS = membrane spanning; QTc = corrected QT interval; SCD = sudden cardiac death; SD = standard deviation.
*
Only the first event for each patient was considered.