Tools to differentiate between Filamin C and Titin truncating variant carriers: value of MRI

Whereas truncating variants of the giant protein Titin (TTNtv) are the main cause of familial dilated cardiomyopathy (DCM), recently Filamin C truncating variants (FLNCtv) were identified as a cause of arrhythmogenic cardiomyopathy (ACM). Our aim was to characterize and compare clinical and MRI features of TTNtv and FLNCtv in the Belgian population. In index patients referred for genetic testing of ACM/DCM, FLNCtv and TTNtv were found in 17 (3.6%) and 33 (12.3%) subjects, respectively. Further family cascade screening yielded 24 and 19 additional truncating variant carriers in FLNC and TTN, respectively. The main phenotype was ACM in FLNCtv carriers whereas TTNtv carriers showed either an ACM or DCM phenotype. Non-sustained Ventricular Tachycardia was frequent in both populations. MRI data, available in 28/40 FLNCtv and 32/52 TTNtv patients, showed lower Left Ventricular (LV) ejection fraction and lower LV strain in TTNtv patients (p < 0.01). Conversely, both the frequency (68% vs 22%) and extent of non-ischemic myocardial late gadolinium enhancement (LGE) was significantly higher in FLNCtv patients (p < 0.01). Hereby, ring-like LGE was found in 16/19 (84%) FLNCtv versus 1/7 (14%) of TTNtv patients (p < 0.01). In conclusion, a large number of FLNCtv and TTNtv patients present with an ACM phenotype but can be separated by cardiac MRI. Whereas FLNCtv patients often have extensive myocardial fibrosis, typically following a ring-like pattern, LV dysfunction without or limited replacement fibrosis is the common TTNtv phenotype.

Long-Term Performance of the Riata/ST Implantable Cardioverter-Defibrillator Lead

Riata and Riata ST implantable cardioverter-defibrillator leads are prone to structural and electrical failure (EF). Our objective was to evaluate Riata/ST lead performance over a long-term follow-up. Of 184 patients having undergone Riata/ST and Riata ST Optim lead implantation from September 2003 to June 2008, 154 patients were evaluated for EF and radiographic conductor externalization (CE). Survival analysis for EF was performed for Riata/ST leads, both for failure-free lead survival and cumulative hazard. Subanalysis on 7Fr leads was performed to evaluate EF and CE rates both for different Riata ST lead management (monitoring vs proactive) and between Riata ST and Riata ST Optim leads. During a mean follow-up of 7 years, Riata/ST lead EF rate was 13% overall. Similar failure-free survival rate was noted for 7Fr as for 8Fr leads (log-rank, p = 0.63). Of all failed leads, 64% failed only after 5 years of follow-up. Compared with the absolute failure rate of 1.84% per device year, cumulative hazard analysis for leads surviving past 5 years revealed an estimated failure rate of 7% per year. No clinical or procedural predictors for EF were found. The subanalysis on 7Fr leads showed an excellent outcome both for a proactive lead management approach as for Optim leads. In conclusion, long-term survival of the Riata/ST lead is impaired with an accelerating EF risk over time. An initial exponential trend was followed by a linear lead failure pattern for leads surviving past 5 years, corresponding to an estimated 7% annual EF rate. These findings may have repercussions on the lead management strategy in patients currently surviving with a Riata/ST lead to prevent significant clinical events like inappropriate shocks or failed device interventions.

Predicting outcome after Fontan palliation: a single-centre experience, using simple clinical variables

BACKGROUND

The Fontan procedure has become the procedure of choice for patients with one functional ventricle. Although perioperative mortality has decreased, late failure of the Fontan circulation remains a major concern. We aimed at (i) describing Fontan patient characteristics and (ii) identifying simple risk factors for outcome.

METHODS

Seventy-three patients (median age 23 y (IQR 19-29 y), 60.3% male) were selected from the database of congenital heart defects. Followup data were collected. The primary end point was composed by death, resuscitation, or heart transplantation.

RESULTS

The most frequently occurring defect was tricuspid atresia (41.1%). Twenty-five (34.2%) and 48 (65.8%) patients received an intra- and extracardiac conduit, respectively. Ten patients reached the primary end point (13.7%) after a median follow-up time of 16 years (IQR 14-19 y). NYHA classification (OR 63.0; 95% Cl 6.7-592.4; P < or =0.001), atrioventricular-valve regurgitation (OR 10.6; 95% Cl: 1.2-94.1; P = 0.034), ventricular function (OR 4.8; 95% Cl 1.7-13.7; P = 0.003), oxygen saturation (OR 0.7; 95% Cl 0.1-1.0; P = 0.002) and the presence (OR 8.6; 95% Cl 1.6-45.2; P = 0.011) or history of supraventricular arrhythmia (OR 6.7; 95% CI: 1.3-35.0; P = 0.025), all parameters gathered at the latest follow-up, were associated with outcome. An association was also found with the presence of an intracardiac conduit (OR 5.8; 95% Cl 1.4-25.1; P = 0.018), higher age at Fontan procedure (OR 1.2; 95% Cl 1.0-1.3; P = 0.007) and male gender (OR 0.2; 95% Cl 0.1-1.0; P = 0.047).

CONCLUSIONS

Complications were not uncommon later after Fontan surgery. Several demographic and procedure-related data were associated with adverse outcome. Interestingly, the strongest correlation was found with clinical and basic echocardiographic characteristics at the latest follow-up.