Mapping potentials adjacent to the cavo-tricuspid isthmus ablation line during incremental pacing: A feasible and highly accurate maneuver to confirm complete CTI conduction block.

BACKGROUND: The diagnostic accuracy of incremental atrial pacing (IP) to determine complete cavo-tricuspid isthmus (CTI) block during typical atrial flutter (AFL) ablation is limited by both an extensive/nonlinear ablation and/or the presence of intra-atrial conduction delay elsewhere in the right atrium. We examined the diagnostic performance of an IP variant based on the assessment of the atrial potentials adjacent to the ablation line which aims at overcoming both limitations. METHODS: From a prospective population of 108 consecutive patients, 15 were excluded due to observation of inconclusive CTI ablation potentials precluding for a straight comparison between the IP maneuver and its variant. In the remaining 93, IP was performed from the low lateral right atrium and the coronary sinus ostium, with the ablation catheter positioned both at the CTI line and adjacent (<5 mm) to its septal and lateral aspect. The IP variant consisted of measuring the interval between the two atrial electrograms situated on the same side of the ablation line, opposite to the pacing site, a ≤10 ms increase indicating complete CTI block. RESULTS: The IP maneuver and its variant were consistent with complete CTI block in 82/93 (88%) and 87/93 (93%) patients, respectively. Four patients had AFL recurrence during follow-up: 2/4 and 4/4 had been adequately classified as incomplete block by the IP maneuver and its variant, respectively. Twenty-three patients (24%) had significant intra-atrial conduction delay elsewhere in the right atrium. The IP maneuver and its variant were suggestive of an incomplete CTI block in 11/23 and 4/23 in this setting (P = .028), with the later best predicting subsequent AFL relapses (2/12 vs 2/4, P = .01). CONCLUSIONS: The IP variant, which was designed to overcome the limitations of the conventional IP maneuver, accurately distinguishes complete from incomplete CTI block and helps to predict AFL recurrences after ablation.

Burning the Gap: Electrical and Anatomical Basis of the Incremental Pacing Maneuver for Cavotricuspid Isthmus Block Assessment.

INTRODUCTION: The incremental pacing (IP) maneuver is a highly specific technique that improves the ability to confirm complete CTI conduction block during typical atrial flutter (AFL) ablation, and reduces long-term AFL recurrences. The purpose of this study is to assess the performance of new catheters equipped with additional high precision bipoles (AHPB) to allow the visualization of the cavotricuspid isthmus (CTI) conduction gap and to compare them with the IP maneuver. METHODS AND RESULTS: Twenty consecutive patients undergoing catheter ablation of the CTI for AFL were included. The IP maneuver confirmed functional versus complete CTI block. Local electrogram analysis using AHPB was then used to assess the presence or absence of gaps across the CTI line. Mean age was 67 years and 80% were male. At the end of the procedure CTI block was achieved in all patients. A transient stage of functional CTI block was observed in 40%. In all cases a continuous fragmented electrogram was present between the double potentials in the CTI in the AHPB channels. In contrast, no electrogram was observed between the CTI double potentials in any of the 20 patients once complete block was confirmed by the IP maneuver. When both techniques were compared a significant association and correlation were observed (chi-square <0.01, Spearman's rho = 1, P < 0.01). CONCLUSION: Catheters equipped with AHPB can aid in the assessment of complete CTI block during AFL ablation procedures by detecting conduction gaps that correlate with incomplete functional block diagnosed by the IP maneuver.

Spatial resolution of defibrillator electrograms to detect distinct exit sites of scar-related ventricular tachycardia.

BACKGROUND: Analysis of implantable cardioverter-defibrillator electrograms (IEGMs) with pacing along the scar edge is often used to approximate distinct exit sites of scar-related ventricular tachycardia (VT). We evaluated the spatial resolution of IEGMs in identifying distinct exit sites of scar-related VT. METHODS AND RESULTS: Seventeen patients with scar-related VT were included. Threshold pacing (500-ms cycle length) was performed at sites spaced 10 mm apart along the scar border, as defined by high-density bipolar voltage mapping. Twelve-lead electrocardiogram and near-field and far-field IEGMs were recorded at each pacing site and assessed for morphology. The average scar size was 60 ± 30 cm(2) and the scar border perimeter measured 28 ± 9 cm. A median of 18 pacing sites per patient were collected, spaced 14 ± 11 mm apart. The mean spatial resolution for the near-field, far-field, and combination of both was 82.7 ± 76 mm, 62.7 ± 53.6 mm, and 56.7 ± 50 mm (P for trend < 0.001). In all cases, IEGM analysis failed to identify distinct VT exit sites spaced <2 cm apart. CONCLUSIONS: Analysis of IEGM morphology with pacing around the edge of the scar is unable to distinguish distinct VT exit sites spaced <2 cm apart, with an average spatial resolution of 5 cm. Given the wide range of values observed, detailed pace mapping over a perimeter of 10-15 cm along the scar edge appears crucial to define the boundaries of a linear ablation strategy to target the VT exit site based on IEGM pace match alone.

Pseudoatrial fibrillation during pacemaker interrogation: what is the mechanism?

BACKGROUND: Normal pacemaker response to magnet and programmer is almost universal and helps to interpret basal rhythm. METHODS AND RESULTS: In this report, we report an undescribed atypical magnet response due to an internal cross-talk with atrial oversensing during a specific part of interrogation, simulating atrial fibrillation.

Merged two-way mapping technique: an alternative 3D electroanatomical mapping approach to guide challenging ablation procedures of accessory pathways with bidirectional conduction properties.

BACKGROUND: Catheter ablation of accessory pathways (AP) with bidirectional conduction may be challenging due to issues related to anatomical course or location. OBJECTIVE: We describe an alternative electro-anatomical mapping technique which aims at depicting the entire anatomic course of the AP from the atrial toward the ventricular insertion in order to guide catheter ablation. METHODS: Twenty consecutive patients with confirmed bidirectional AP conduction and at least one previous ablation procedure or para-Hisian location were included. 3-D electro-anatomical mapping was used to depict the merged 10-ms isochrone area of maximum early activation of both the ventricular and atrial signals during sinus rhythm and ventricular pacing/orthodromic tachycardia, respectively. Catheter ablation was performed within the depicted earliest isochrone area. RESULTS: Acute bidirectional AP conduction block was achieved in all patients 4.2 ± 1.7 s after the first radiofrequency energy pulse was delivered, without reconnection during a 30 ± 10 min post-ablation observation time. No procedural complications were seen. After a mean follow-up period of 9 ± 7 months (range 3 to 16), no recurrences were documented. CONCLUSION: This merged two-way mapping technique is a safe, efficient, and effective technique for ablation of APs with bidirectional conduction.

Influence of PACE score and conduction disturbances in the incidence of early new onset atrial fibrillation after typical atrial flutter ablation.

PURPOSE: Patients undergoing cavotricuspid isthmus (CTI) ablation for typical flutter (AFL) have a high incidence of new onset atrial fibrillation (AF). We aimed to analyze the influence of PACE score to predict new onset AF in this subset of patients to stratify thromboembolic risk. METHODS: Between 2017 and 2019, patients undergoing CTI ablation for AFL and without history of AF were prospectively included. All patients were monitored continuously by implantable loop recorder and followed by remote monitoring. RESULTS: Overall 48 patients were included. New onset AF rate at 12 months was 56.3%. We observed two very strong independent predictors for new onset AF: a PACE score ≥ 30 (HR:6.9; 95% CI:1.71-27.91; p = 0.007) and an HV interval ≥ 55 (HR:11.86; 95% CI:2.57-54.8; p = 0.002). CONCLUSIONS: The incidence of newly diagnosed AF is high in patients with AFL after CTI ablation, and can occur early. A high PACE score and/or long HV interval predict even higher risk, and may be useful in the decision for empiric long-term anticoagulation.

Changes in hospital mortality rates in 425 patients with acute ST-elevation myocardial infarction and cardiac rupture over a 30-year period.

BACKGROUND: Possible changes in the incidence and outcome of cardiac rupture in patients with ST-elevation myocardial infarction over a long period of time have not been investigated. METHODS AND RESULTS: The incidence of cardiac rupture in ST-elevation myocardial infarction patients and its mortality rate were investigated during a 30-year period divided into 5 intervals (1977 to 1982, 1983 to 1988, 1989 to 1994, 1995 to 2000, and 2001 to 2006). Of a total of 6678 consecutive patients, 425 experienced a free wall rupture (280 with cardiac tamponade: 227 with electromechanical dissociation and 53 with hypotension) or a septal rupture (145). After the exclusion of referrals from other centers (n=44), the incidence of definite cardiac rupture (septal rupture, anatomic evidence of free wall rupture, or electromechanical dissociation) declined progressively (6.2% in 1977 to 1982 to 3.2% in 2001 to 2006; P<0.001) in parallel with a progressive use of reperfusion therapy (0% to 75.1%; P<0.001). In addition, among patients with cardiac rupture, there was a progressive fall in the rate of death (94% to 75%; P<0.001) despite a trend toward increasing age (66+/-8 to 75+/-8 years; P<0.054) in conjunction with better control of systolic blood pressure at 24 hours (130+/-24 versus 110+/-18 mm Hg; P<0.001); an increased use of reperfusion therapy (0% to 59%; P<0.001), beta-blockers (0% to 45%; P<0.001), angiotensin-converting enzyme inhibitors (0% to 38%; P<0.001), and aspirin (0% to 96%; P<0.001); and a lower use of heparin (99% to 67%; P<0.001). CONCLUSIONS: The decline in the incidence in cardiac rupture and its rate of death over the last 30 years appears to be associated with the increasing use of reperfusion strategies and adjunct medical therapy.

High incidence of TIMI flow 0 to I in patients with ST-elevation myocardial infarction without electrocardiographic lytic criteria.

BACKGROUND: Most patients with ST-elevation myocardial infarction fulfilling ST-segment elevation (STE) lytic criteria present an occluded culprit artery but the occlusion rate in those with minimal STE (minSTE) not fulfilling lytic criteria is unknown. METHODS: In 63 patients with minSTE (mean STE:1.2 +/- 0.6 mm) and 149 with lytic STE criteria (lyticSTE, 4.8 +/- 3.1 mm), an emergency coronary angiography was performed, serial creatine kinase-MB was determined, and ejection fraction was measured by 2-dimensional echocardiography. RESULTS: The 2 groups showed similar time from pain onset to electrocardiogram (minSTE 196 +/- 199 vs lyticSTE, 176 +/- 172 min, P = .444), and although time to catheterization was longer in patients with minSTE (426 +/- 314 vs 253 +/- 239 min, P < .001), the rate of TIMI flow 0 to I (88% vs 81%, P = .21) was similar and percutaneous coronary intervention was performed in >80% of patients from the 2 groups. Moreover, patients with minSTE had higher rate of collateral circulation (27% vs 13%, P = .013), lower rate of Q waves (44% vs 60%, P = .041), lower creatine kinase-MB (202 +/- 150 vs 335 +/- 280, microg/L, P < .001), higher ejection fraction (54% +/- 9% vs 49% +/- 12%, P = .004), and lower mortality (0% vs 7.4%, P = .036). CONCLUSIONS: ST-elevation myocardial infarction patients with minSTE present a high prevalence of TIMI flow 0 to I similar to those meeting lyticSTE suggesting an identical underlying mechanism and the potential to benefit from primary angioplasty.

Double factor single shot to diminish complications in cryoballoon ablation procedures for atrial fibrillation.

PURPOSE: Cryoballoon ablation (CBA) has become a standard treatment for recurrent atrial fibrillation (AF). There is need for improved CBA protocols. We aimed to demonstrate that a new protocol including minimum temperature (minT) reached could reduce procedure times and complications. METHODS: A new double factor protocol (DFP), based on the performance of one single shot per vein with variable duration, and conditional bonus shot, determined by time-to-effect (TTE) and minT, was compared with the conventional protocol (CP), with at least two shots per vein. Procedure parameters, complications, and efficacy were compared. RESULTS: We prospectively included 88 consecutive patients treated with the DFP. These were compared to the previous consecutive 69 patients treated with CP. All procedures were performed with 28-mm second-generation balloon. Acute pulmonary vein (PV) isolation was similar (98.6% vs. 98.9% in CP vs. DFP, p = 0.687). Procedure and ablation times favored DFP over CP (120 vs. 134 min, p = 0.003; and 1051 vs. 1475 s, p < 0.001; respectively). A composite of major and minor complications was significantly reduced in the DFP compared to the CP (18.8% vs. 6.8%, p = 0.02; respectively). Within a follow-up of 18 months, freedom from AF was 79.7% in CP and 78.4% in DFP (Log-rank 0.501). Paroxysmal AF and absence of PV potentials predicted better arrhythmia outcomes (HR 2.14 for paroxysmal vs. persistent, p = 0.031; and HR 1.61 for absence vs. presence of PV potentials, p = 0.01). CONCLUSIONS: The novel DFP results in reduced complication rates and procedure times, with similar success rates compared with a conventional strategy.

Simple predictors for new onset atrial fibrillation.

BACKGROUND: Predicting atrial fibrillation is a tremendous challenge. Only few studies have included 24h-Holter monitoring characteristics to predict new onset AF (NOAF). OBJECTIVES: Our aim is to define simple predictors for NOAF. METHODS: The study population included 468 patients undergoing Holter for any cause. After excluding 169 patients for history of AF prior to or during the Holter monitoring period, 299 patients were assessed for incidence of NOAF. RESULTS: Age at inclusion was 62.5±18years (53.5% male). After a median follow up of 39.1 [IQI 36.6-40] months, the incidence of NOAF was 10.4%. With univariate analysis, age, hypertension, diabetes, renal impairment, heart failure/cardiomyopathy, left ventricle ejection fraction ≤50%, left atrium diameter ≥40mm, CHA2DS2 VASc ≥4, premature atrial complexes (PAC) ≥0.2%, and PR interval were associated with NOAF. With multivariate analysis, age (HR 1075; p=0.001 per year), presence of heart failure/cardiomyopathy (HR 6,16; p<0.001), PAC≥0.2% (HR 3,32; p=0.003) and PR interval (HR 1.011; p=0.006 per millisecond) were independent predictors for NOAF. Those predictors were used to create a risk calculator for NOAF, which was validated in an independent cohort of 200 consecutive patients with similar baseline characteristics. This new tool resulted in good discrimination capacity calculated by the C index for NOAF prediction: Area under curve (AUC) (95% CI) 0.794 (0.714-0.875) at 2years and 0.794 (0.713-0.875) at 3years. CONCLUSIONS: Simple clinical, ECG and Holter monitoring parameters are able to predict NOAF in a broad population and may help guide more rigorous monitoring for atrial fibrillation.

Risk of pacemaker implantation after uneventful successful cavotricuspid isthmus radiofrequency ablation in patients with common atrial flutter.

INTRODUCTION: Little is known about the risk of pacemaker implantation after common atrial flutter ablation in the long-term. METHODS: We retrospectively reviewed the electrophysiology laboratory database at two Spanish University Hospitals from 1998 to 2012 to identify patients who had undergone successful ablation for cavotricuspid dependent atrial flutter. Cox regression analysis was used to examine the risk of pacemaker implantation. RESULTS: A total of 298 patients were considered eligible for inclusion. The mean age of the enrolled patients was 65.7±11. During 57.7±42.8 months, 30 patients (10.1%) underwent pacemaker implantation. In the stepwise multivariate models only heart rate at the time of the ablation (OR: 0.96; 95% CI: 0.93-0.98; p<0.0001) and intraventricular conduction disturbances in the baseline ECG (OR: 3.87; 95% CI: 1.54-9.70; p=0.004) were independents predictors of the need of pacemaker implantation. A heart rate of ≤65 bpm was identified as the optimal cut-off value to predict the need of pacemaker implantation in the follow-up (sensitivity: 79%, specificity: 74%) by ROC curve analyses. CONCLUSION: This is the first study of an association between the slow conducting common atrial flutter and subsequent risk of pacemaker implantation. In light of these findings, assessing it prior to ablation can be helpful for the risk stratification of sinus node disease or atrioventricular conduction disease requiring a pacemaker implantation in patients with persistent atrial flutter.

Implantable Cardioverter-defibrillator Therapy for Hypertrophic Cardiomyopathy: Usefulness in Primary and Secondary Prevention.

INTRODUCTION AND OBJECTIVES: Hypertrophic cardiomyopathy is a frequent cause of sudden death. Clinical practice guidelines indicate defibrillator implantation for primary prevention in patients with 1 or more risk factors and for secondary prevention in patients with a history of aborted sudden death or sustained ventricular arrhythmias. The aim of the present study was to analyze the follow-up of patients who received an implantable defibrillator following the current guidelines in nonreferral centers for this disease. METHODS: This retrospective observational study included all patients who underwent defibrillator implantation between January 1996 and December 2012 in 3 centers in the province of Barcelona. RESULTS: The study included 69 patients (mean age [standard deviation], 44.8 [17] years; 79.3% men), 48 in primary prevention and 21 in secondary prevention. The mean number of risk factors per patient was 1.8 in the primary prevention group and 0.5 in the secondary prevention group (P=.029). The median follow-up duration was 40.5 months. The appropriate therapy rate was 32.7/100 patient-years in secondary prevention and 1.7/100 patient-years in primary prevention (P<.001). Overall mortality was 10.1%. Implant-related complications were experienced by 8.7% of patients, and 13% had inappropriate defibrillator discharges. CONCLUSIONS: In patients with a defibrillator for primary prevention, the appropriate therapy rate is extremely low, indicating the low predictive power of the current risk stratification criteria.

Update in cardiac arrhythmias and pacing.

This article discusses the main advances in cardiac arrhythmias and pacing published between 2013 and 2014. Special attention is given to the interventional treatment of atrial fibrillation and ventricular arrhythmias, and on advances in cardiac pacing and implantable cardioverter defibrillators, with particular reference to the elderly patient.

ECG de julio de 2018 / ECG, July 2018

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Respuesta al ECG de julio de 2018 / Response to ECG, July 2018

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