Three-dimensional cardiac magnetic resonance allows the identification of slow-conducting anatomical isthmuses in tetralogy of Fallot.

BACKGROUND AND AIMS: Patients with repaired tetralogy of Fallot remain at risk of life-threatening ventricular tachycardia related to slow-conducting anatomical isthmuses (SCAIs). Preventive ablation of SCAI identified by invasive electroanatomical mapping is increasingly performed. This study aimed to non-invasively identify SCAI using 3D late gadolinium enhancement cardiac magnetic resonance (3D-LGE-CMR). METHODS: Consecutive tetralogy of Fallot patients who underwent right ventricular electroanatomical mapping (RV-EAM) and 3D-LGE-CMR were included. High signal intensity threshold for abnormal myocardium was determined based on direct comparison of bipolar voltages and signal intensity by co-registration of RV-EAM with 3D-LGE-CMR. The diagnostic performance of 3D-LGE-CMR to non-invasively identify SCAI was determined, validated in a second cohort, and compared with the discriminative ability of proposed risk scores. RESULTS: The derivation cohort consisted of 48 (34 ± 16 years) and the validation cohort of 53 patients (36 ± 18 years). In the derivation cohort, 78 of 107 anatomical isthmuses (AIs) identified by EAM were normal-conducting AI, 22 were SCAI, and 7 blocked AI. High signal intensity threshold was 42% of the maximal signal intensity. The sensitivity and specificity of 3D-LGE-CMR for identifying SCAI or blocked AI were 100% and 90%, respectively. In the validation cohort, 85 of 124 AIs were normal-conducting AI, 36 were SCAI, and 3 blocked AI. The sensitivity and specificity of 3D-LGE-CMR were 95% and 91%, respectively. All risk scores showed an at best modest performance to identify SCAI (area under the curve ≤ .68). CONCLUSIONS: 3D late gadolinium enhancement cardiac magnetic resonance can identify SCAI with excellent accuracy and may refine non-invasive risk stratification and patient selection for invasive EAM in tetralogy of Fallot.

The R″ wave in V1 and the negative terminal QRS vector in aVF combine to a novel 12-lead ECG algorithm to identify slow conducting anatomical isthmus 3 in patients with tetralogy of Fallot.

AIMS: Patients with repaired tetralogy of Fallot (rTOF) have an increased risk of ventricular tachycardia (VT), with slow conducting anatomical isthmus (SCAI) 3 as dominant VT substrate. In patients with right bundle branch block (RBBB), SCAI 3 leads to local activation delay with a shift of terminal RV activation towards the lateral RV outflow tract which may be detected by terminal QRS vector changes on sinus rhythm electrocardiogram (ECG). METHODS AND RESULTS: Consecutive rTOF patients aged ≥16 years with RBBB who underwent electroanatomical mapping at our institution between 2017-2022 and 2010-2016 comprised the derivation and validation cohort, respectively. Forty-six patients were included in the derivation cohort (aged 40±15 years, QRS duration 165±23 ms). Among patients with SCAI 3 (n = 31, 67%), 17 (55%) had an R″ in V1, 18 (58%) had a negative terminal QRS portion (NTP) ≥80 ms in aVF, and 12 (39%) had both ECG characteristics, compared to only 1 (7%), 1 (7%), and 0 patient without SCAI, respectively.Combining R″ in V1 and/or NTP ≥80 ms in aVF into a diagnostic algorithm resulted in a sensitivity of 74% and specificity of 87% in detecting SCAI 3. The inter-observer agreement for the diagnostic algorithm was 0.875. In the validation cohort [n = 33, 18 (55%) with SCAI 3], the diagnostic algorithm had a sensitivity of 83% and specificity of 80% for identifying SCAI 3. CONCLUSION: A sinus rhythm ECG-based algorithm including R″ in V1 and/or NTP ≥80 ms in aVF can identify rTOF patients with a SCAI 3 and may contribute to non-invasive risk stratification for VT.

Ventricular Tachycardia Ablation in Adult Congenital Heart Disease.

Patients with congenital heart disease (CHD) are at risk for late ventricular tachycardia (VT) and sudden cardiac death. Slow conducting anatomical isthmuses, bordered by unexcitable tissue created by valve annuli, ventricular incisions, and prosthetic material are the dominant substrate for macroreentrant monomorphic VTs in repaired CHD. These well-defined substrates allow for catheter or surgical transection with clear endpoints. This review elaborates on VT substrates in various CHD, and evolving mapping and ablation approaches. Because most research is conducted in patients with repaired tetralogy of Fallot, this malformation will serve as a paradigm.

Fever worsens outcomes in animal models of ischaemic stroke: A systematic review and meta-analysis.

BACKGROUND: Subfebrile temperatures and fever in the first days after stroke are associated with a greater risk of a poor outcome. If this relation is causal, prevention of hyperthermia may improve outcome. Causality can be tested in animal models. We therefore assessed the effects of hyperthermia on outcomes in animal models of ischaemic stroke and explored under which conditions prevention of hyperthermia could be most effective. METHODS: We performed a systematic review and meta-analysis of data from animal experiments testing the effect of spontaneous or induced hyperthermia on outcome after focal cerebral ischaemia. Our primary outcome measure was infarct size. Normalised mean differences were combined using the random effects model and stratified meta-analysis was used to explore the impact of study characteristics. RESULTS: We included 19 publications, reporting on 49 comparisons involving 603 animals. Overall, hyperthermia increased infarct size by 43.4% (95% confidence interval, 29.8-56.9%) and worsened neurobehavioral outcomes by 48.5% (17.2-79.8%). The increase in infarct size was larger with higher temperatures. Hyperthermia was most harmful if present for more than 2 h and when started at the time of artery occlusion rather than later. CONCLUSION: Hyperthermia substantially increased infarct size in animal models of ischaemic stroke, suggesting that the relation between fever and poor outcome observed in patients is at least in part causal. These data provide support to trials testing the effect of the prevention of fever with antipyretic drugs in patients with acute stroke.