Flecainide causing elevated capture thresholds on pacemaker implantation.

Flecainide is a Vaughan Williams class 1c antiarrhythmic used to treat supraventricular and ventricular arrhythmias. It has been described as a rare cause for increased pacemaker capture thresholds. We describe a report of a patient, in her early 80s, presenting with tachy-brady syndrome on a background of permanent atrial fibrillation. She was treated with metoprolol and flecainide by her private cardiologist. Permanent right ventricular chamber pacing was recommended for her slow heart rate. At insertion of her single chamber pacemaker, she was noted to have elevated capture thresholds despite appropriate lead positioning. A flecainide level was elevated at 1.1 µg/mL, and it was subsequently ceased. This was associated with a rapid improvement in her capture threshold. Flecainide should be considered as a cause for elevated pacing thresholds at the time of implant. Particular care should be taken for at-risk groups such as the elderly and patients with renal impairment.

Computerized tomography image correlation of His bundle/deep septal pacing location and outcomes: an analysis from the Canberra HIs bundle/deep septal Pacing Study (CHIPS).

BACKGROUND: Localisation of the conduction system under fluoroscopy is not easy and the ideal location of the pacing leads in physiological pacing is still being debated. OBJECTIVE: The primary aim was to assess the lead locations using cardiac CT scan. Secondary aims were clinical outcomes including success and safety of the procedure and lead performance. METHODS: Of the 100 consecutive patients who received physiological pacing, 34 patients underwent follow-up cardiac CT scan. The four different types of pacing were identified as His bundle (HBP), para-Hisian, left bundle branch (LBBP), and deep septal pacing. RESULTS: Most patients had successful HBP via the right atrium (RA) (87.5%) as compared to the right ventricle (RV) (12.5%). Lower thresholds were observed when leads were placed within 2 mm of the junction of the membranous and muscular ventricular septum. Unlike HBP, LBBP was possible at a wide region of the septum and selective capture of individual fascicles was feasible. LBBP showed deeper penetration of leads into the septum, as compared to deep septal pacing (70% vs. 45%). Approximately, 80% of patients did not have an intra-ventricular portion of the membranous septum. CONCLUSIONS: The anterior part of the atrio-ventricular (AV) septum at the junction between the membranous and muscular septum via RA appeared to be the best target to successfully pace His bundle. LBBP was possible at a wide region of the septum and selective capture of individual fascicle was feasible. Adequate depth of penetration of lead was very important to capture the left bundle.

Symptom-to-Balloon Time is a Strong Predictor of Adverse Events Following Primary Percutaneous Coronary Intervention: Results From the Australian Capital Territory PCI Registry.

BACKGROUND: Notwithstanding improvements in door-to-balloon time, adverse event rates after primary PCI have remained steady. We analysed the effect of symptom-to-balloon (STB) time, a reflection of total ischaemic time, on major adverse cardiovascular events (MACE) and explored predictors of prolonged STB time. METHODS: The study population included 1002 consecutive patients (22.4% women) with a mean age of 62.3±13.2 years, who underwent primary PCI during 2008-2014. Groups were compared for STB ≤ and >240min. Primary endpoint was one-year MACE, a composite of death, reinfarction, stent thrombosis or target vessel revascularisation. RESULTS: Symptom-to-balloon time was available in 893 patients of which 588 (65.8%) had STB ≤240min and 305 (34.2%) had STB >240min. The incidence of one-year MACE increased significantly in a stepwise manner with increasing STB time (p for trend=0.003). Symptom-to-balloon time was an independent predictor of one-year MACE along with age >70 years, final TIMI flow <3, three vessel disease, cardiogenic shock and out-of-hospital cardiac arrest. We also performed a multivariate analysis to determine predictors of delayed treatment. Predictors of STB time >240min were age >70 years, female gender, diabetes, absence of prehospital catheter laboratory activation and presentation to a non-PCI centre. CONCLUSION: Incidence of MACE was strongly correlated with STB time and STB time was an independent predictor of MACE. We have identified specific subgroups with prolonged STB times (age >70, female gender, diabetes, absence of prehospital activation and presentation to a non-PCI centre). This information should inform future studies and strategies to minimise delays in these subgroups for improved outcomes.

Shorter ischaemic time and improved survival with pre-hospital STEMI diagnosis and direct transfer for primary PCI.

BACKGROUND: We sought to determine if our regional program for pre-hospital STEMI diagnosis and direct transfer for primary PCI (PPCI) was associated with shorter ischaemic times and improved survival compared with ED diagnosis. METHODS: STEMI diagnosis was made at the scene by pre-hospital ECG or in local EDs depending on patient presentation. Ambulance ECGs were transmitted to our ED for cath lab activation. Patient variables and outcomes at 12 months were recorded. RESULTS: We treated 782 consecutive patients with PPCI during January 2008-June 2013. Cath lab activation was initiated prior to hospital arrival (pre-hospital) in 24% of cases and by ED in 76% of cases. Median total ischaemic time was 154 min for pre-hospital and 211 minutes for ED patients (p<0.0001). Mortality at 12 months was 7.9% in the ED group compared with 3.7% in the pre-hospital group (p=0.036). On multivariate Cox regression analysis including baseline and procedural variables, pre-hospital activation remained an independent predictor of mortality (HR 0.45, 95% CI 0.20-1.0, p=0.03). CONCLUSIONS: Pre-hospital diagnosis of STEMI and direct transfer to the cath lab reduced total ischaemic time by 57 minutes and mortality by >50% following PPCI. Further efforts are needed to increase the proportion of STEMI patients treated using this strategy.

Efficacy of non-compliant balloon post-dilation in optimization of contemporary stents: A digital stent enhancement study.

BACKGROUND: There is no evidence from randomized trials for the benefit of routine non-compliant balloon (NCB) post-dilation after stent deployment. Despite being the gold standard, intravascular ultrasound is infrequently performed due to time and cost constraints and a suitable alternative technology is required for routine assessment of stent expansion. The purpose of this study was to assess the contribution of NCB post-dilation in optimizing contemporary stents by using digital stent enhancement (DSE). METHODS: We treated 120 patients with stent insertion and assessed the stents with DSE before and after NCB use. Optimal expansion was defined as the minimum stent diameter (MSD) ≥ 90% of the nominal stent diameter, an adaptation of the MUSIC and POSTIT trial criteria. Stent deployment was performed at 12 atm pressure followed by routine NCB post-dilation at ≥ 14 atm. RESULTS: The mean reference diameter on QCA was 2.75 mm (SD 0.63) and mean stent diameter was 3.15 mm (SD 0.46). At a mean stent deployment pressure of 11.7 atm (SD 2.4), only 21% of stents were optimally expanded. After NCB inflation at a mean of 16.9 atm (SD 2.8), MSD increased by 0.26 mm (SD 0.24), optimal stent expansion increased from 21% to 58% and mean stent symmetry ratio increased from 0.83 to 0.87 (p < 0.0001). CONCLUSIONS: Contemporary stents are sub-optimally expanded in the majority of cases after standard deployment compared with nominal sizes. Adjunctive NCB post-dilation optimized an additional 37% of stents. DSE analysis can assist in qualitative and quantitative stent assessments and can potentially facilitate a selective NCB post-dilation strategy to achieve optimal stent expansion.