Background: Andersen-Tawil Syndrome (ATS) is an autosomal dominant channelopathy classified as long QT syndrome (LQTS) type 7, Characterized by periodic paralysis, ventricular ectopy/arrhythmia, and dysmorphic features. According to different authors, prolonged QTc is not always present, and thus it should be reclassified. However, no studies have found the correlation to life-threatening arrhythmias (LTAs) and prolong QTc. This study compared the likelihood of LTAs like VT and VF in ATS patients with prolonged QTc intervals against those with normal QTc.

Methods: To enable a meta-analysis, we searched literature reviews of reported cases or cohort studies with ATS between 1994 and 2024. Cases were selected if they presented a cardiologic affection. Prolong QTc interval was defined as QTc 440 msec in females and 460 msec for males. Each variable was calculated using the validated percentage. Numerical variables are expressed as mean and SD. Categorical variables are expressed as percentages. Student’s t-test was used for numerical variables. Categorical variables were analyzed using chi-square. Values of p <0.05 were considered statistically significant.

Results: 209 cardiologic-affected cases with ATS that provided information regarding the QTc interval were included. Of these, only 45.5% evidenced a prolonged QTc with a mean of 490  37 msec. ATS Probands were more likely to present a prolonged QTc than affected family members (51% vs. 29% respectively p = 0.008). Patients with prolonged QTc presented lower odds of a U wave than those with normal QTc (43% vs. 75%, respectively p = 0.004). Although there was no statistical significance when comparing LTAs in patients with prolonged QTc to normal QTc, LTAs were similar in both groups. VT episodes were more likely present with prolonged QTc than normal QTc (79% vs. 72%). However, episodes of sustained VT were more commonly present in cases with prolonged QTc than normal QTc (20% vs. 12%). Torsade de points and VF were more likely present in patients with a prolonged QTc interval than normal QTc (6% vs. 3% and 14% vs. 13%, respectively). Non-fatal cardiac arrest was slightly more common in cases with prolonged QTc than normal QTc (13% vs. 9%). Both prolonged and normal QTc had the same percentage of SCD (3%).

Conclusion: Although ATS has been classified as a long QT syndrome, prolongation is not always present. Patients with prolonged QTc demonstrated only a slightly increased percentage of developing LTAs compared to those with normal QTc.