Transcoronary pacing to assess myocardial viability prior to percutaneous coronary intervention: Pilot study to assess feasibility.

BACKGROUND: The assessment of myocardial viability is crucial before percutaneous coronary intervention (PCI) is carried out to ensure that the patient will gain benefit. Trans-coronary pacing (TCP) has previously been used to pace myocardium but may also provide information on myocardial viability. METHODS: Patients with a single, significant coronary stenosis requiring PCI were recruited. They underwent a cardiac MRI to assess myocardial viability. Prior to PCI, a coronary guidewire was used to measure pacing threshold, impedance, and R-wave amplitude in different myocardial segments to determine any association between the electrical parameters and myocardial viability. RESULTS: Eight patients were recruited and six patients underwent intervention. Pacing sensitivity did not demonstrate statistically significant differences between normal and scarred myocardium. Impedance demonstrated a mean of 304.8 ± 74.0 Ω in normal myocardium (NM), 244.1 ± 66.6 Ω in <50% myocardial scar (MS), and 222.3 ± 33.8 Ω in ≥50% MS. Pacing threshold demonstrated a mean of 1.960 ± 1.226 V in NM, 5.009 ± 2.773 V in <50% MS, and 3.950 ± 0.883 V in ≥50% MS. For both impedance and threshold, there was a significant difference among the groups (P = 0.12 and P = 0.002, respectively), and post hoc Tukey's pairwise comparison demonstrated significant differences between NM and scarred myocardium. No significant differences were found between <50% MS and ≥50% MS. CONCLUSIONS: Impedance and pacing threshold, measured during TCP, can be used to differentiate between normal myocardium and scarred myocardium. Further research is needed to determine whether TCP can discriminate between viable and nonviable myocardium.

Intra-cardiac and peripheral levels of biochemical markers of fibrosis in patients undergoing catheter ablation for atrial fibrillation.

AIMS: Measurement of circulating biomarkers of fibrosis may have a role in selecting patients and treatment strategy for catheter ablation. Pro-collagen type III N-terminal pro-peptide (PIIINP), C-telopeptide of type I collagen (ICTP), fibroblast growth factor 23 (FGF-23), and galectin 3 (gal-3) have all been suggested as possible biomarkers for this indication, but studies assessing whether peripheral levels reflect intra-cardiac levels are scarce. METHODS AND RESULTS: We studied 93 patients undergoing ablation for paroxysmal atrial fibrillation (AF) (n = 63) or non-paroxysmal AF (n = 30). Femoral venous, left and right atrial, and coronary sinus blood were analysed using ELISA to determine biomarker levels. Levels were compared with control patients (n = 36) and baseline characteristics, including left atrial voltage mapping data. C-telopeptide of type I collagen levels were higher in AF than in non-AF patients (P = 0.007). Peripheral ICTP levels were higher than all intra-cardiac levels (P < 0.001). Peripheral gal-3 levels were higher than left atrial levels (P = 0.001). Peripheral levels of FGF-23 and PIIINP were not significantly different from intra-cardiac levels. CS levels of ICTP were higher than right and left atrial levels (P < 0.001). gal-3 was higher in women vs. men (P ≤ 0.001) and with higher body mass index (P ≤ 0.001). ICTP levels increased with reducing ejection fraction (P ≤ 0.012). CONCLUSIONS: Atrial fibrillation patients have higher levels of circulating ICTP than matched non-AF controls. In AF ablation patients, intra-cardiac sampling of FGF-23 or PIIINP gives no further information over peripheral sampling. For gal-3 and ICTP, intra-cardiac sampling may be necessary to assess their association with intra-cardiac processes. None of the biomarkers is related to fibrosis assessed by left atrial voltage.

Normal heart ventricular tachycardia associated with pregnancy: successful treatment with catheter ablation.

BACKGROUND: Normal heart ventricular arrhythmia occurring during pregnancy has been previously described. Whilst there are established reports of catheter ablation to treat supraventricular arrhythmia during pregnancy, there are no reports of ablation to treat ventricular tachycardia. CASE: We present the case of a 36 year old women, 31 weeks into an otherwise uncomplicated pregnancy, experiencing significant, troublesome and drug refractory tachycardia emanating from the right ventricular outflow tract. CONCLUSION: We describe a successful radio frequency ablation in the third trimester of pregnancy.

An unusual cause of a haemothorax following pacemaker implantation: A case report.

Background: Haemothoraces are a reported but extremely rare complication of pacemaker implantation. Haemothoraces can be a consequence of lead perforation through the right ventricle (RV) and pericardium into the pleural space, direct lung or vascular injury during access. Case summary: A 72-year-old woman presented 24 h after a pacemaker implantation with chest pain and shortness of breath. Computed tomography of the chest confirmed perforation of the RV lead into the left pleural cavity with a large left sided haemothorax. Following percutaneous drainage of the left sided haemothorax, the patient became haemodynamically unstable necessitating emergent sternotomy. During surgery, the extra-cardiac portion of the pacing lead was cut, the RV repaired and a large haematoma evacuated from the left pleural space. Despite this, the patient remained hypotensive, and further exploration showed a bleeding intercostal artery that had been lacerated by the pacing lead. This was treated by electrocautery, and the patient's haemodynamic status improved. The RV lead remnant was removed transvenously via the subclavian vein, and the patient was left with a single chamber atrial pacemaker. Discussion: Prompt recognition of RV lead perforation and its associated sequalae, often utilising multi-modality imaging, is vital to enable transfer to a centre with cardiac surgical expertise. In this case, the perforating RV lead lacerated an intercostal artery, and this was only identified at the time of surgery. In order to minimize the risk of perforation, multiple fluoroscopic views should be used, and care should be taken during helix deployment.

Gender differences in sympathetic neural activation following uncomplicated acute myocardial infarction.

AIMS: To determine whether the magnitude of post-acute myocardial infarction (AMI) sympathetic activation is greater in women (F-AMI) than men (M-AMI). METHODS AND RESULTS: Both sympatho-humoral activation and female gender are associated with worse outcome in the early phase following AMI. However, women have lower sympathetic output than men. We therefore examined matched groups of F-AMI (18) and M-AMI (18) patients 2-4 days following uncomplicated AMI, then 3 monthly to 9 months; matched normal control (NC) groups comprised M-NC (18) and F-NC (18). Muscle sympathetic nerve activity (MSNA) was measured by microneurography. Muscle sympathetic nerve activity was lower in the F-NC than M-NC (at least P < 0.05) and greater in the two AMI groups than their corresponding NC groups (at least P < 0.001). Muscle sympathetic nerve activity was similar in the F-AMI and M-AMI groups indicating a post-AMI increase in women of about twice that in men (P < 0.0001). Both AMI groups returned to corresponding NC (lower in women) levels by 9 months. CONCLUSION: Following uncomplicated AMI, women developed a relatively greater magnitude of sympathetic activation lasting until its resolution at 9 months. This is consistent with reports of their worse prognosis observed during this time period, with important potential clinical implications.

Multicentre randomised trial comparing contact force with electrical coupling index in atrial flutter ablation (VERISMART trial).

INTRODUCTION: Electrical coupling index (ECI) and contact force (CF) have been developed to aid lesion formation during catheter ablation. ECI measures tissue impedance and capacitance whilst CF measures direct contact. The aim was to determine whether the presence of catheter / tissue interaction information, such as ECI and CF, reduce time to achieve bidirectional cavotricuspid isthmus block during atrial flutter (AFL) ablation. METHODS: Patients with paroxysmal or persistent AFL were randomised to CF visible (range 5-40g), CF not visible, ECI visible (change of 12%) or ECI not visible. Follow-up occurred at 3 and 6 months and included a 7 day ECG recording. The primary endpoint was time to bidirectional cavotricuspid isthmus block. RESULTS: 114 patients were randomised, 16 were excluded. Time to bidirectional block was significantly shorter when ECI was visible (median 30.0 mins (IQR 31) to median 10.5mins (IQR 12) p 0.023) versus ECI not visible. There was a trend towards a shorter time to bidirectional block when CF was visible. Higher force was applied when CF was visible (median 9.03g (IQR 7.4) vs. 11.3g (5.5) p 0.017). There was no difference in the acute recurrence of conduction between groups. The complication rate was 2%, AFL recurrence was 1.1% and at 6 month follow-up, 12% had atrial fibrillation. CONCLUSION: The use of tissue contact information during AFL ablation was associated with reduced time taken to achieve bidirectional block when ECI was visible. Contact force data improved contact when visible with a trend towards a reduction in the procedural endpoint. ClinicalTrials.gov trial identifier: NCT02490033.

Left atrial voltage, circulating biomarkers of fibrosis, and atrial fibrillation ablation. A prospective cohort study.

AIMS: To test the ability of four circulating biomarkers of fibrosis, and of low left atrial voltage, to predict recurrence of atrial fibrillation after catheter ablation. BACKGROUND: Circulating biomarkers potentially may be used to improve patient selection for atrial fibrillation ablation. Low voltage areas in the left atrium predict arrhythmia recurrence when mapped in sinus rhythm. This study tested type III procollagen N terminal peptide (PIIINP), galectin-3 (gal-3), fibroblast growth factor 23 (FGF-23), and type I collagen C terminal telopeptide (ICTP), and whether low voltage areas in the left atrium predicted atrial fibrillation recurrence, irrespective of the rhythm during mapping. METHODS: 92 atrial fibrillation ablation patients were studied. Biomarker levels in peripheral and intra-cardiac blood were measured with enzyme-linked immunosorbent assay. Low voltage (<0.5mV) was expressed as a proportion of the mapped left atrial surface area. Follow-up was one year. The primary endpoint was recurrence of arrhythmia. The secondary endpoint was a composite of recurrence despite two procedures, or after one procedure if no second procedure was undertaken. RESULTS: The biomarkers were not predictive of either endpoint. After multivariate Cox regression analysis, high proportion of low voltage area in the left atrium was found to predict the primary endpoint in sinus rhythm mapping (hazard ratio 4.323, 95% confidence interval 1.337-13.982, p = 0.014) and atrial fibrillation mapping (hazard ratio 5.195, 95% confidence interval 1.032-26.141, p = 0.046). This effect was also apparent for the secondary endpoint. CONCLUSION: The studied biomarkers do not predict arrhythmia recurrence after catheter ablation. Left atrial voltage is an independent predictor of recurrence, whether the left atrium is mapped in atrial fibrillation or sinus rhythm.

Gender-related differences in the sympathetic vasoconstrictor drive of normal subjects.

The risk of cardiovascular disease has been linked to sympathetic activation and its incidence is known to be lower in women than in men. However, the effect of gender on the sympathetic vasoconstrictor drive has not yet been established. In the present study, we investigated whether there is a gender difference in MSNA (muscle sympathetic nerve activity) and blood flow, and to determine the mechanisms involved. We examined 68 normal subjects, 34 women and 34 men, matched for age, BMI (body mass index) and waist circumference. MSNA was measured as the mean frequency of single units (s-MSNA) and as multi-unit bursts (m-MSNA) from the peroneal nerve simultaneously with its supplied muscle CBF (calf blood flow). Women had lower (P=0.0007) s-MSNA (24+/-2.0 impulses/100 cardiac beats) than men (34+/-2.3 impulses/100 cardiac beats), and a greater baroreceptor reflex sensitivity controlling efferent sympathetic nerve activity than men. The sympathetic activity was inversely and directly correlated respectively, with CBF (P=0.03) and CVR (calf vascular resistance; P=0.01) in men only. The responses of an increase in CVR to cold pressor and isometric handgrip tests were significantly smaller in women (P=0.002) than in men, despite similar increases in efferent sympathetic nerve activity. Women had a lower central sympathetic neural output to the periphery, the mechanism of which involved differences in central and reflex control, as well as a lower vasoconstrictor response to this neural output. It is suggested that this may partly explain the observed lower incidence of cardiovascular events in women compared with men.

Empirical anticoagulation for patients in sinus rhythm at high risk of ischaemic stroke: A review of current literature.

Ischaemic stroke is one of the commonest causes of morbidity and mortality worldwide and around a fifth of events can be attributed to a cardioembolic source. This is typically due to atrial fibrillation (AF), the most common sustained cardiac arrhythmia. However, AF can, at times, be difficult to detect due to a relative lack of symptoms and the fact that it can be paroxysmal in nature. Studies have shown that diagnosis of AF improves as the length of cardiac monitoring increases. However, prolonged cardiac monitoring is not a cost-effective way of diagnosing AF. Therefore, an alternative approach may be to empirically anticoagulate individuals who are at high risk of stroke. This article summarises current evidence surrounding stroke risk prediction, the use of anticoagulation in the secondary prevention of stroke and its use in the primary prevention of stroke in high risk groups with the aim of determining whether empirical anticoagulation is a safe and effective strategy.

The sympathetic drive after acute myocardial infarction in hypertensive patients.

BACKGROUND: Sympathetic activation occurs in hypertension (HT) and after acute myocardial infarction (AMI) and is related to greater cardiovascular risk. Also, AMI in patients with HT (AMI-HT) carries greater risk than that in normal subjects (AMI-NT). We therefore planned to determine whether the sympathetic activation and its duration after AMI are greater in patients with antecedent HT than in patients with normal arterial pressure (NT). METHODS: In 68 matched subjects with uncomplicated AMI-HT (n = 17), AMI-NT (n = 17), HT (n = 17), and NT (n = 17), we measured resting muscle sympathetic nerve activity (MSNA) as the mean frequency of multiunit bursts (m-MSNA) and single units (s-MSNA). In AMI groups data were obtained 2 to 4 days after AMI and then at 3-month intervals until MSNA returned to levels found in HT and NT. RESULTS: The AMI-HT had greater (at least P < 0.05; ANOVA) s-MSNA (99 +/- 3.5 impulses/100 cardiac beats) than AMI-NT (84 +/- 2.8 impulses/100 cardiac beats). During follow up, s-MSNA hyperactivity in AMI-HT was always greater than in AMI-NT, and returned to values found in HT and NT (84 +/- 3.5 impulses/100 cardiac beats and 62 +/- 4.4 impulses/100 cardiac beats, respectively) 9 months after AMI. Similar results were obtained for m-MSNA. CONCLUSIONS: AMI in hypertensives resulted in greater MSNA levels lasting at least 6 months longer than AMI in normotensives. This indicates that AMI further augmented the MSNA hyperactivity of HT and that this could be one mechanism involved in the reported worse prognosis in AMI-HT.

Screening For Atrial Fibrillation In The Community Using A Novel ECG Recorder.

Aims: MyDiagnostick (MDK) is a novel portable ECG recorder. We conducted this study to evaluate its role in screening for atrial fibrillation (AF). Methods: The device is a cylindrical rod with metallic electrodes at both ends recording electrocardiogram (ECG) when both electrodes are held. Individuals were requested to hold the device for approximately 15 s, the device was then connected to a laptop (with proprietary software downloaded) and analysed. Anonymised ECGs were stored for further analysis. A total of 855 ECGs were recorded and analysed offline by two arrhythmia specialists assessing ECG quality, in particular the level of noise. A noise score (NS) was devised regarding ECG quality. Results: Seven individuals were found with unknown AF (0,8%). In general ECG quality was good and rhythm diagnosis was certain with total interobserver agreement. Conclusion: The MDK provided a rapid and accurate rhythm analysis and has potential implications in preventing ischaemic cardio-embolic stroke.

Genetics of congenital and drug-induced long QT syndromes: current evidence and future research perspectives.

The long QT syndrome (LQTS) is a condition characterized by abnormal prolongation of the QT interval with an associated risk of ventricular arrhythmias and sudden cardiac death. Congenital forms of LQTS arise due to rare and highly penetrant mutations that segregate in a Mendelian fashion. Over the years, multiple mutations in genes encoding ion channels and ion channel binding proteins have been reported to underlie congenital LQTS. Drugs are by far the most common cause of acquired forms of LQTS. Emerging evidence suggests that drug-induced LQTS also has a significant heritable component. However, the genetic substrate underlying drug-induced LQTS is presently largely unknown. In recent years, advances in next-generation sequencing technology and molecular biology techniques have significantly enhanced our ability to identify genetic variants underlying both monogenic diseases and more complex traits. In this review, we discuss the genetic basis of congenital and drug-induced LQTS and focus on future avenues of research in the field. Ultimately, a detailed characterization of the genetic substrate underlying congenital and drug-induced LQTS will enhance risk stratification and potentially result in the development of tailored genotype-based therapies.

Ongoing requirement for pacing post-transcatheter aortic valve implantation and surgical aortic valve replacement.

OBJECTIVES: Transcatheter aortic valve implantation (TAVI) is an established intervention for aortic stenosis. While it is known that the requirement for permanent pacing is higher following CoreValve (Medtronic, Inc., Minneapolis, MN, USA) TAVI than after surgical aortic valve replacement (SAVR), it remains uncertain whether pacing is required in the medium-to-long term. We hypothesized that complete heart block following TAVI is more likely to resolve than that following SAVR. METHODS: A retrospective analysis of prospectively collated data on 528 patients undergoing TAVI or SAVR from May 2008 to December 2010 at a cardiac tertiary referral hospital. Demographic data, timing and indication for pacing post-procedure plus follow-up were recorded. Paced patients were compared and analysed by existing initial indication for pacing. RESULTS: In total, 31 (5.9%) patients received a pacemaker, and there were limited differences between not paced and paced patient characteristics by procedure type. Of these, a greater proportion were implanted post-TAVI compared with SAVR (17 vs 3.2%, P<0.001). The mean time to pacemaker follow-up for TAVI and SAVR was 234 and 188 days, P=0.32, respectively. Fewer patients compared with pacing indication remained in complete heart block at latest follow-up for TAVI (76.5 vs 33.3%, P=0.02) and SAVR (92.9 vs 58.3%, P=0.04). Although, there was a trend towards a greater magnitude of TAVI patients regaining atrioventricular nodal conduction, this did not differ significantly from that seen in SAVR patients. CONCLUSIONS: In keeping with previous reports, this single-centre experience demonstrates that patients undergoing TAVI have higher rates of pacemaker implantation than those following SAVR. However, pacing indication in the short-to-medium term may not persist for all paced patients post-TAVI and -SAVR with the suggestion that a significant proportion recover atrioventricular conduction, which tended to be greatest in TAVI paced patients.

Cardiac magnetic resonance imaging of a patient with an magnetic resonance imaging conditional permanent pacemaker.

Cardiac magnetic resonance imaging (MRI) is increasingly used as the optimum modality for cardiac imaging. An aging population and rising numbers of patients with permanent pacemakers means many such individuals may require cardiac MRI scanning in the future. Whilst the presence of a permanent pacemaker is historically regarded as a contra-indication to MRI scanning, pacemaker systems have been developed to limit any associated risks. No reports have been published regarding the use of such devices with cardiac MRI in a clinical setting. We present the safe, successful cardiac MRI scan of a patient with an MRI-conditional permanent pacing system.

Sympathetic nerve hyperactivity and its effect in postmenopausal women.

OBJECTIVES: Hypertension and its subsequent cardiovascular complications have been associated with sympathetic neural activation, and their prevalence in women increases after the menopause. However, there have been no data on the level of sympathetic activation and its relationship to vascular blood flow following the menopause. Therefore, we planned to find out whether the behavior of muscle sympathetic nerve activity (MSNA) and calf blood flow (CBF) in women with and without essential hypertension (EHT) is changed following the menopause. METHODS: Peroneal nerve activity was measured as mean frequency of single units and of multiunit bursts with simultaneously measured CBF in two matched groups of postmenopausal women with and without EHT in comparison with two matched groups of premenopausal women with and without EHT. RESULTS: As expected, nerve activity was greater in the hypertensive than in normotensive groups and in postmenopausal than in premenopausal normotensive groups. We found that single unit frequency in postmenopausal hypertensives (65 ± 3.9 impulses/100 cardiac beats) was not significantly different from that in postmenopausal normotensives (54 ± 2.2 impulses/100 cardiac beats) or in premenopausal hypertensives (57 ± 2.8 impulses/100 cardiac beats). Similar results were obtained for burst frequency. In addition, a statistically significant negative correlation between the frequency of nerve activity and CBF was found only in postmenopausal normotensive (at least r =  -0.42, P < 0.04) and hypertensive women (at least r =  -0.45, P < 0.03). CONCLUSION: These findings suggest that sympathetic nerve hyperactivity in postmenopausal women may have greater vascular effects than in premenopausal women, and could have implications in the management of EHT in postmenopausal women.