Clinical and angiographic outcomes following percutaneous treatment of non-occlusive vs. chronically total occluded coronary lesions

Background

Recent advancements in recanalization techniques, introduction of dedicated equipment and elaboration of systematic algorithmic approaches have significantly improved procedural success of coronary chronic total occlusion (CTO) percutaneous coronary intervention (PCI) procedures. However, despite their undisputable merits in terms of procedural success, direct comparisons of mid-term clinical and angiographic outcomes following CTO and non-CTO-PCI are missing.

Purpose

The aim of this study was to assess the clinical and angiographic outcomes of patients undergoing successful CTO-PCI as compared to a propensity matched cohort of patients undergoing PCI of non-occlusive coronary lesions.

Methods

All consecutive patients undergoing successful CTO recanalization procedures at our center between 2015 and 2018 were included (N=453; 472 lesions). For matching purposes, all patients undergoing non-CTO-PCI present in our database were included (N=14733; 23458 lesions). A 1-to-1 nearest neighbour matching using baseline clinical and angiographic variables was performed to identify one patient undergoing non-CTO-PCI (N=453; 472 vessels) for each patient undergoing CTO-PCI (N=453; 472 vessels). Surveillance angiography was scheduled at 6–9 months and clinical follow-up was performed up to 12 months. The primary clinical endpoint of interest was the incidence of major adverse cardiovascular events (MACE), a composite of all-cause death, myocardial infarction (MI) and target lesion revascularization (TLR). The secondary angiographic endpoint was in-segment binary restenosis.

Results

Patients undergoing CTO-PCI displayed a tendency towards higher degrees of binary restenosis at surveillance angiography as compared to those undergoing non-CTO-PCI (CTO vs. non-CTO: 30.5% vs. 24.0%; P=0.058), despite not meeting statistical significance. Of note, the incidence of occlusive restenosis was low and comparable between groups (2.2% vs. 1.4%; P=0.603). At 12 months follow-up, MACE occurred in 83 patients (19.7%) in the CTO-PCI and 59 patients (14.1%) in the non-CTO-PCI group (hazard ratio [HR] = 1.44; 95% confidence interval [CI]: 1.03–2.01; P=0.033). TLR rates were significantly higher following CTO- as compared to non-CTO-PCI (17.2% vs. 10.3%; HR=1.72 [1.18–2.51], P=0.005). The incidence of all-cause death (2.6% vs. 3.3%; P=0.548) and MI (0.5% vs. 1.4%; P=0.177) was not significantly different between the groups.

Conclusion

In this large, propensity-matched comparison of clinical and angiographic outcomes following CTO- vs. non-CTO-PCI, we found CTO-PCI to be associated with a higher MACE rate at 12 months, primarily driven by significantly higher TLR rates. The incidence of occlusive restenosis was low and comparable between groups.

Funding Acknowledgement

Type of funding sources: None.

Ticagrelor or prasugrel in patients with acute coronary syndrome and high bleeding risk

Background

The relative efficacy and safety of more potent P2Y12 inhibitors in patients with acute coronary syndrome (ACS) and high bleeding risk (HBR) undergoing percutaneous coronary intervention (PCI) remains unclear.

Purpose

To study the treatment effect of ticagrelor and prasugrel in PCI patients presenting with ACS and HBR.

Methods

This post-hoc analysis of the ISAR-REACT 5 trial included patients with ACS undergoing PCI, randomized to ticagrelor or prasugrel, in whom HBR was defined as per Academic Research Consortium criteria. The primary (efficacy) endpoint was the composite of all-cause death, myocardial infarction, or stroke. The secondary (safety) endpoint was Bleeding Academic Research Consortium (BARC) type 3 to 5 bleeding. Outcomes were assessed 12 months after randomisation.

Results

Out of the 3,239 patients included in this analysis, 486 fulfilled the criteria for ARC-HBR definition (HBR group; ticagrelor, n=230 and prasugrel, n=256), whilst 2,753 did not (non-HBR group; ticagrelor, n=1,375 and prasugrel, n=1,378). Compared to the non-HBR group, the HBR group had a higher risk for the primary (hazard ratio [HR]=3.57, 95% confidence interval [CI], 2.79–4.57, p<0.001), and secondary endpoint (HR=2.94 [2.17–3.99], p<0.001). In the HBR group, the primary (HR=1.09; [0.73–1.62]) and secondary (HR=1.18 [0.67–2.08]) endpoints were not statistically different between patients assigned to ticagrelor and prasugrel. In the non-HBR group, the primary endpoint (HR=1.62 [1.19–2.20]) occurred more frequently in patients assigned to ticagrelor as compared to patients assigned to prasugrel, without difference in safety (HR=1.08 [0.74–1.58]). There was no treatment allocation-by-HBR status interaction with respect to the primary (p for interaction = 0.123), or secondary (p for interaction = 0.803) endpoints.

Conclusions

In patients with ACS undergoing PCI, HBR status increased both ischemic and bleeding risks without significant impact on the relative efficacy or safety of ticagrelor versus prasugrel. These results warrant confirmation in larger cohorts.

Funding Acknowledgement

Type of funding sources: Public grant(s) – National budget only. Main funding source(s): German Center for Cardiovascular Research (DZHK)Deutsches Herzzentrum München

Ticagrelor or prasugrel in patients with acute coronary syndrome and prior myocardial infarction

Objectives

To investigate the efficacy and safety of ticagrelor versus prasugrel in patients with acute coronary syndrome (ACS) and prior myocardial infarction (MI).

Background

The efficacy and safety of ticagrelor versus prasugrel in ACS patients with prior MI remains unstudied.

Methods

Patients with ACS scheduled for an invasive strategy and randomized to ticagrelor or prasugrel in the ISAR-REACT 5 trial with available information concerning prior MI were included in the present analysis. The primary endpoint was the composite of all-cause death, myocardial infarction, or stroke; the secondary endpoint was Bleeding Academic Research Consortium (BARC) type 3 to 5 bleeding. Endpoints were assessed 12 months after randomization.

Results

A total of 4,015 patients were included in this analysis (prior MI= 631 patients; no prior MI = 3,384 patients). As compared to patients without prior MI, the primary endpoint occurred more frequently in patients with prior MI (12.6% vs. 7.2%; hazard ratio [HR] = 1.78, 95% confidence interval [CI] 1.38–2.29; p= <0.001) without significant difference in terms of secondary endpoint between groups (5.8% vs. 5.7%; HR=1.02 [0.71–1.45]; p=0.921). Patients with prior MI randomized to ticagrelor versus prasugrel displayed higher risk for primary (HR=1.62 [1.03–2.55]) but not secondary endpoint (HR=1.28 [0.56–2.91]). Patients without prior MI randomized to ticagrelor or prasugrel displayed no significant difference in terms of primary (HR=1.28 [0.99–1.65]) or secondary endpoints (HR=1.13 [0.82–1.55]). There was no treatment assignment-by-prior MI status interaction with respect to the primary (p for interaction = 0.373) and the secondary (p for interaction= 0.786) endpoints.

Conclusions

Patients with ACS and prior MI are at higher risk for recurrent ischemic but not bleeding events. The history of MI does not affect the relative efficacy and safety of ticagrelor versus prasugrel in patients with ACS.

Funding Acknowledgement

Type of funding sources: Public grant(s) – National budget only. Main funding source(s): German Center for Cardiovascular Research (DZHK)Deutsches Herzzentrum München

Efficacy and safety of ticagrelor versus prasugrel in smokers and nonsmokers with acute coronary syndromes

Background

The efficacy and safety of ticagrelor versus prasugrel according to smoking status in patients with acute coronary syndromes (ACS) are not known.

Purpose

The aim of this study was to assess the efficacy and safety of ticagrelor versus prasugrel according to smoking status in patients with ACS undergoing invasive evaluation.

Methods

This pre-specified analysis of the ISAR-REACT 5 trial included 1349 smokers and 2652 nonsmokers randomised to receive ticagrelor or prasugrel. The primary endpoint was the incidence of death, myocardial infarction, or stroke; the secondary endpoint was the incidence of Bleeding Academic Research Consortium (BARC) type 3 to 5 bleeding. Both endpoints were assessed at 12 months after randomisation.

Results

There was no significant treatment arm-by-smoking status interaction regarding the efficacy outcome. The primary endpoint occurred in 47 patients (7.0%) in the ticagrelor group and 41 patients (6.2%) in the prasugrel group in smokers (hazard ratio [HR]=1.15; 95% confidence interval [CI] 0.76–1.75; P=0.510) and in 133 patients (10.2%) in the ticagrelor group and 94 patients (7.2%) in the prasugrel group in nonsmokers (HR=1.44 [1.10–1.87], P=0.007; Pint=0.378). The secondary endpoint occurred in 27 patients (4.6%) in the ticagrelor group and 33 patients (5.6%) in the prasugrel group in smokers (HR=0.81 [0.49–1.35]; P=0.412) and in 66 patients (6.0%) in the ticagrelor group and 46 patients (4.4%) in the prasugrel group in nonsmokers (HR=1.38 [0.94–2.01]; P=0.097).

Conlusions

Although there was no significant interaction between smoking and treatment effect, the present findings suggest a greater advantage of prasugrel over ticagrelor in nonsmoker vs. smoker patients with ACS.

Funding Acknowledgement

Type of funding sources: Public grant(s) – National budget only. Main funding source(s): German Centre for Cardiovascular Research;Deutsches Herzzentrum München, Germany

Body mass index and efficacy and safety of ticagrelor versus prasugrel in patients with acute coronary syndromes

Background

The efficacy and safety of ticagrelor versus prasugrel in patients with acute coronary syndromes (ACS) according to body mass index (BMI) remain unknown.

Purpose

To assess the efficacy and safety of ticagrelor versus prasugrel in patients with ACS according to BMI.

Methods

This post-hoc analysis of the ISAR-REACT 5 trial included 3987 patients with BMI data available. BMI was grouped in 3 categories: low (BMI<25 kg/m2, n=1084), intermediate (BMI ≥25 to <30 kg/m2, n=1890) and high (BMI≥30 kg/m2, n=1013). The primary endpoint was the 12-month incidence of all-cause death, myocardial infarction, or stroke. The secondary endpoint was the 12-month incidence of Bleeding Academic Research Consortium (BARC) type 3 to 5 bleeding.

Results

There was no significant treatment arm-by-BMI interaction regarding the primary endpoint (Pint=0.578). However, the primary endpoint occurred in 63 patients assigned to ticagrelor and 39 patients assigned to prasugrel in the low BMI group (11.7% vs. 7.5%; hazard ratio [HR]=1.62; 95% confidence interval [CI], 1.09–2.42; P=0.018), 78 patients assigned to ticagrelor and 58 patients assigned to prasugrel in the intermediate BMI group (8.3% vs. 6.2%; HR=1.36 [0.97–1.91]; P=0.076), and 43 patients assigned to ticagrelor and 37 patients assigned to prasugrel in the high BMI group (8.6% vs. 7.3%; HR=1.18 [0.76–1.84]; P=0.451). BARC type 3 to 5 bleeding events did not differ between ticagrelor and prasugrel in patients with low (6.5% vs. 6.6%), intermediate (5.6% vs. 5.0%), or high (4.4% vs. 2.8%) BMI.

Conclusions

BMI of patients with ACS did not impact significantly on the treatment effect of ticagrelor vs. prasugrel in terms of both efficacy and safety.

Funding Acknowledgement

Type of funding sources: Public grant(s) – National budget only. Main funding source(s): German Center for Cardiovascular Research;Deutsches Herzzentrum München, Germany

Cardiac procedural myocardial injury, infarction and mortality in patients undergoing elective PCI: a pooled analysis of patient-level data

Background

The prognostic implications of cardiac procedural myocardial injury and infarction (MI) in chronic coronary syndrome patients undergoing elective percutaneous coronary intervention (PCI) is still debated.

Objective

To determine the optimal cardiac troponin threshold for identifying prognostically important events.

Methods

Using a pooled dataset of nine registries and one randomized trial, we analysed individual data of 14,433 patients undergoing elective PCI with a normal or moderately elevated baseline pre-PCI cardiac troponin (cTn). A multivariate model was performed to evaluate the associations between post-PCI cTn elevation and 1-year mortality after PCI, including thresholds used by existing procedural myocardial injury definitions (Fourth Universal Definition of MI [UDMI] and Academic Research Consortium 2 [ARC-2] / Society for Cardiovascular Angiography and Interventions (SCAI)). The association between type 4a MI and 1-year mortality was also evaluated.

Results

Procedural myocardial injury defined by the Fourth UDMI occurred in 52.5% of patients and was not associated with 1-year mortality (adjOR 1.27, 95% CI [0.90–1.81] p=0.18). The association between post-PCI cTn elevation and 1-year mortality was significant above a 3-fold increase above the upper reference limit, and was optimal for a 5.2-fold increase which corresponded to an 18.3% rate of event, and an adjOR of 2.03 (95% CI [1.31–3.14], p=0.002) (figure). Procedural myocardial injury defined by the ARC-2/SCAI definition occurred in 1.3% of the patients, had a strong association with 1-year mortality (adjOR 4.15, 95% CI [1.62–10.64], p<0.01) but lacked sensitivity (5.2% sensitivity). Type 4a MI occurred in 12.7% of patients, was strongly associated with 1-year mortality (adjOR 3.18, 95% CI [1.47–6.90], p=0.002), but could only be evaluated in a subset of patients (n=3 084) with available data on new myocardial ischaemia post-PCI.

Conclusions

We have demonstrated that a post-PCI cTn elevation ≥5x the 99th percentile URL in CCS patients with normal baseline cTn, represents the optimal threshold for defining prognostically important or “Major” procedural myocardial injury in the absence of evidence for new myocardial ischaemia. Major procedure related myocardial injury and type 4a MI should be considered as a quality metric and endpoints in clinical trials.

Adjusted OR of mortality at 1 year

Funding Acknowledgement

Type of funding source: None

Influence of treatment modality and neointimal characteristics on optical coherence tomography on clinical outcomes of in-stent restenosis

Background

In-stent restenosis (ISR) represents the more frequent modality of stent failure. The currently recommended treatment strategies are represented by repeat drug-eluting stent (DES) implantation or drug-coated balloon (DCB) angioplasty. Optical coherence tomography can display important information regarding mechanisms of stent failure as well as neointimal characterization.

Purpose

Aim of the present study was to determine the impact of treatment modality (DES vs. DCB) as well as neointimal characteristics (homogeneous vs. non-homogeneous) as determined by intravascular OCT, on clinical outcomes and explore whether there is an interaction between neointimal pattern of ISR and treatment modality.

Methods

Patients presenting with ischemic symptoms and/or evidence of myocardial ischemia in three European centers and undergoing intravascular OCT prior to percutaneous coronary intervention (PCI) for ISR, were retrospectively included in this study. Characterization of neointimal tissue was performed at the frame displaying the maximal %AS as well as the 5 preceding and following analyzed frames. Each frame was subdivided in 4 quadrants (90°) and the neointimal characteristics separately characterized for each of them. Based on its optical characteristics, neointimal tissue was categorized as homogeneous, heterogeneous, layered or neoatherosclerosis.

Based on the dominant neointimal type, the study population was divided in two groups, (predominantly homogeneous and non-homogeneous). Primary endpoints of the study were represented by major adverse cardiac events (MACE) and its idividual components (death, cardiac death, myocardial infarction and target lesion revascularization (TLR)) at 2 years follow-up.

Results

A total of 197 patients undergoing OCT prior to PCI for ISR were included in this study. 100 patients were classified as having predominantly homogeneous and 97 as having predominantly non-homogeneous neointima.

No association was found between predominant OCT pattern (homogenous vs. non-homogenous) and MACE at 2 years follow-up (HR=1.01, 95% CI: 0.59–1.75; p=0.94), or the individual MACE components. Analogously, no significant differences in terms of MACE at 2 years were found between predominantly homogeneous vs. non-homogeneous neointima in the patient subgroup receiving a DES (p=0.10) and in that undergoing DCB treatment (p=0.11).

However, a significant interaction was found between neointimal tissue pattern and treatment modality in terms of MACE (p=0.02) aa well as death or MI (p=0.016). Predominantly non-homogeneous neointima in patients treated with DCB was associated with a higher incidence of MACE.

Conclusions

Our results indicate that there is a significant interaction between treatment modality of ISR (DES vs. DCB) and neointimal pattern as determined by intravascular OCT. These results land initial support to an OCT-guided treatment of ISR and should be confirmed by larger trials.

Funding Acknowledgement

Type of funding source: None

A comparison of gamma-glutamyl transferase and alkaline phosphatase as prognostic markers in patients with coronary heart disease

BACKGROUND AND AIMS

Whether gamma-glutamyl transferase (GGT) or alkaline phosphatase (ALP) is a better prognostic marker in patients with coronary heart disease (CHD) remains unknown. The aim of this study was to compare the prognostic value of GGT and ALP in patients with CHD.

METHODS AND RESULTS

This study included 3768 patients with CHD. The main study outcome was 3-year all-cause mortality. The median values of GGT and ALP were 36.2 U/L and 69.3 U/L. Patients were divided into subgroups according to GGT or ALP activity > or ≤median. Overall, there were 304 deaths: 195 deaths occurred in patients with GGT >median (n = 1882) and 109 deaths occurred in patients with GGT ≤median (n = 1886); Kaplan-Meier [KM] estimates of all-cause mortality were 11.9% and 6.4% (unadjusted hazard ratio [HR] = 1.85, 95% confidence interval [CI], 1.46 to 2.34]; P < 0.001). According to ALP activity, 186 deaths occurred in patients with ALP >median (n = 1883) and 118 deaths occurred in patients with ALP ≤median (n = 1885); KM estimates of all-cause mortality were 11.4% and 7.1% (unadjusted HR = 1.64 [1.30-2.06]; P < 0.001). After adjustment, GGT (adjusted HR = 1.32 [1.11-1.58]; P = 0.002) but not ALP (adjusted HR = 1.20 [1.00-1.43]; P = 0.051, with both HR calculated per 1 unit increment in logarithmic GGT or ALP scale) remained significantly associated with the risk for mortality. The C statistic of the mortality model with GGT was greater than the C statistic of the model with ALP (0.831 [0.802-0.859] vs. 0.826 [0.793-0.855]; P < 0.001).

CONCLUSIONS

In patients with CHD, GGT was a stronger correlate of all-cause mortality than ALP.

A gender-specific analysis of association between hyperuricaemia and cardiovascular events in patients with coronary artery disease

BACKGROUND AND AIMS

Gender-related differences in the association between hyperuricaemia and cardiovascular events remain poorly understood. The objective of this study was to assess gender-related differences in the association between hyperuricaemia and cardiovascular events in patients with coronary artery disease (CAD).

METHODS AND RESULTS

This study included 13,273 patients with CAD. Hyperuricaemia was defined as a plasma uric acid >7.0mgdl(-1) in men and >5.7mgdl(-1) in women. The primary outcome was 1-year all-cause mortality. Hyperuricaemia was found in 3745 men (36.5%) and 1562 women (50.3%); odds ratio (OR)=1.76, 95% confidence interval (CI) 1.62-1.91; P<0.001. Women with hyperuricaemia were older, had higher proportions of patients with diabetes and arterial hypertension and had reduced renal function and higher C-reactive protein levels compared with men with hyperuricaemia. One-year all-cause mortality was 9.3% (n=143) in women with hyperuricaemia versus 6.9% (n = 252) in men with hyperuricaemia (P=0.002). After adjustment in multivariable Cox proportional hazards model, uric acid predicted 1-year mortality with an adjusted hazard ratio (HR)=1.17, 95% CI (1.03-1.31), P=0.012 in men and HR=1.25, 95% CI (1.06-1.48), P=0.007 in women, for each standard deviation increase in the natural logarithm. Uric acid predicted 1-year mortality with an area under the receiver-operating characteristic curve=0.625, 95% CI (0.594-0.656) in men and 0.676, 95% CI (0.635-0.717) in women (P=0.044, for women versus men).

CONCLUSION

Hyperuricaemia predicts an increased risk of 1-year mortality in both genders with a stronger association in women. Differences in cardiovascular risk profile may explain the stronger association between hyperuricaemia and cardiovascular events in women.

Aspirin and clopidogrel with or without phenprocoumon after drug eluting coronary stent placement in patients on chronic oral anticoagulation

OBJECTIVES

Optimal antithrombotic/anticoagulation therapy in patients on chronic oral anticoagulation (OAC) undergoing drug-eluting stent (DES) implantation is unknown. We investigated the efficacy and safety of two regimens of antithrombotic/anticoagulation therapy in patients who present for DES implantation whilst on OAC.

METHODS

We included a series of 515 patients on OAC who underwent DES implantation between 2002 and 2007. Based on predefined clinical and echocardiographic criteria, 306 patients continued OAC (triple therapy) and 209 patients discontinued OAC (dual therapy) for the time they received antiplatelet therapy with clopidogrel and aspirin [stent-related antithrombotic treatment (SRAT)]. The primary end point was a composite of death, myocardial infarction, stent thrombosis or stroke.

RESULTS

During SRAT the primary endpoint was observed in 13 patients in the group with triple therapy versus 15 patients in the group with dual therapy [Kaplan-Meier estimates 4.2% and 7.2%, odds ratio (OR) = 0.61, 95% confidence interval (CI) 0.29-1.28; P = 0.19]. At 2 years of follow-up, the primary endpoint was observed in 35 patients in the group with triple therapy versus 36 patients in the group with dual therapy (Kaplan-Meier estimates 14.1% and 18.0%, OR = 0.76, 95% CI: 0.48-1.21; P = 0.25). Two-year incidence of major bleeding was 1.4% (n = 4, triple therapy) versus 3.1% (n = 6, dual therapy) (P = 0.34).

CONCLUSIONS

In patients on chronic OAC undergoing DES implantation, clinical and echocardiographic criteria help to define postprocedural antithrombotic/anticoagulation therapy. Based on these criteria, both a double antiplatelet therapy (clopidogrel plus aspirin) and a triple therapy (OAC plus clopidogrel plus aspirin) are associated with favourable safety and efficacy.

Myeloperoxidase level in patients with stable coronary artery disease and acute coronary syndromes

BACKGROUND

No studies have measured plasma myeloperoxidase (MPO) across the entire spectrum of patients with coronary artery disease (CAD). The aim of the study was to compare MPO level across the entire spectrum of CAD, to assess the accuracy of MPO in predicting acute coronary syndromes and to define independent correlates of MPO level.

DESIGN

This case-control study included 874 patients with angiographically proven CAD. Cases included 680 patients with CAD (382 patients with stable CAD, 107 patients with non-ST-segment elevation acute coronary syndromes and 191 patients with ST-segment elevation acute myocardial infarction). Controls included 194 subjects with normal coronary angiograms. MPO was measured using an enzyme immunoassay before angiography and heparin administration.

RESULTS

MPO level [median (25th-75th percentiles)] was 74.5 (52.5-135.3) microg L(-1) in cases vs. 61.2 (44.6-80.9), microg L(-1) in controls (P < 0.001). MPO level was 61.2 (47.5-85.8), microg L(-1) in patients with stable CAD, 99.2 (62.2-154.9), microg L(-1) in patients with non-ST-segment elevation acute coronary syndromes and 129.5 (72.2-216.0) microg L(-1) in patients with acute myocardial infarction (P < 0.001). Elevated MPO level was associated with acute coronary syndromes with an area under receiver operating characteristic (ROC) curve of 0.731 (95% confidence interval 0.692-0.770; P < 0.001). Independent correlates of MPO level were acute coronary syndrome (P < 0.001), high-sensitivity C-reactive protein (P = 0.007), creatinine (P = 0.026), left ventricular ejection fraction (P = 0.027, negative association) and smoking (P = 0.028).

CONCLUSIONS

MPO level is elevated in patients with CAD and higher levels of MPO were found with progression of CAD from stable CAD to non-ST-segment elevation acute coronary syndromes and to acute myocardial infarction.

Left and right ventricular diastolic functions in patients with rheumatoid arthritis without clinically evident cardiovascular disease

The aim of this study was to assess the prevalence of diastolic dysfunction of the left ventricle (LV) and of the right ventricle in patients with rheumatoid arthritis (RA) without clinically evident cardiovascular manifestations and to estimate whether there is a correlation between the duration of RA and the degree of LV diastolic dysfunction. The study included 81 patients (61 females and 20 males) with RA without clinically evident heart disease (group 1) and 40 healthy subjects (29 females and 11 males) who served as a control group (group 2). Both groups were matched for age and sex. Echocardiographic and Doppler studies were conducted in all patients with RA and control subjects. There were significant differences between patients with RA vs. control group with regard to early diastolic flow velocity (E), atrial flow velocity (A) and the E/A ratio (0.68 +/- 0.19 m/s vs. 0.84 +/- 0.14 m/s, p < 0.001; 0.73 +/- 0.15 m/s vs. 0.66 +/- 0.13 cm/s, p = 0.01; and 0.97 +/- 0.3 vs. 1.32 +/- 0.37, p < 0.001, respectively). There was significant difference between groups regarding the right ventricular early diastolic (Er)/atrial (Ar) flow velocities (Er/Ar ratio) (1.07 +/- 0.3 vs. 1.26 +/- 0.3, p = 0.002). There was a weak correlation between transmitral E/A ratio and the duration of RA (r = - 0.22, p = 0.001). Myocardial performance index (MPI) appeared to differ little in patients with RA as compared with control group (0.51 +/- 0.1 vs. 0.52 +/- 0.2, p = NS). In patients with RA without clinically evident cardiovascular disease, the left ventricular diastolic function and the right ventricular diastolic function are reduced. Left ventricular wall thickness, dimensions, systolic function and MPI were found to be normal. LV diastolic function had a weak correlation with the duration of RA.

Dissimilar atrial rhythms: coexistence of reentrant atrial tachycardia, atrioventricular nodal reentrant tachycardia and interatrial conduction block

We report a patient in whom mapping of the right atrium with multipolar catheters and electroanatomic mapping revealed the presence of three dissimilar rhythms: a reentrant atrial tachycardia in the antero-lateral wall of the right atrium and an atrioventricular nodal reentrant tachycardia (AVNRT) isolated from each other and a conduction disturbance at the interatrial septum resulting in a rate-related interatrial block and a slow left atrial rhythm. The AVNRT was stopped with intravenous adenosine (6 mg) and induced repeatedly by atrial extrastimuli associated with a critical atrioventricular delay and dual atrioventricular nodal pathways. Electroanatomic mapping disclosed extensive fibrosis isolating viable myocardium of the antero-lateral wall from the rest of the right atrium. The viable myocardium in the antero-lateral wall was activated by a reentrant rhythm circulating around an islet of fibrosis located in the middle of the viable tissue. The AVNRT was ablated by a standard approach and the reentrant atrial tachycardia by producing a linear lesion bridging the central islet of fibrosis with the anterior tricuspid annulus. This case highlights the complicated nature of some dissimilar atrial rhythms and the power of electroanatomic mapping tools to reveal the exact mechanism and guide radiofrequency ablation.

Noncontact mapping-guided ablation of atrial flutter and enhanced-density mapping of the inferior vena caval-tricuspid annulus isthmus

Three-dimensional visualization of cardiac activation has become important in providing further insights into pathophysiological mechanisms of arrhythmias and to increase the efficacy of catheter ablation. The noncontact mapping enables a single beat analysis in a reconstructed geometry of the cardiac chamber. The aim of the study was to describe three-dimensional activation patterns and inferior vena caval-tricuspid annulus (IVC-TA) isthmus conduction characteristics in patients with atrial flutter and the noncontact guidance of the radiofrequency ablation of this arrhythmia. In 34 patients with atrial flutter, the noncontact probe was deployed in the RA. The global three-dimensional activation and the isthmus conduction (enhanced density mapping) were delineated during ongoing a trial flutter and paced rhythms. Ablation was performed nonfluoroscopically based on reconstructed anatomy and conduction patterns. Noncontact mapping was compared and validated with conventional multielectrode technique. IVC-TA isthmus ablation was completed successfully in 33 (97%) of 34 patients. In one patient a lower loop reentry around the inferior vena cava was depicted as a mechanism of atrial flutter. In another patient with positive flutter waves in inferior leads, an activation pattern typical of counterclockwise flutter was demonstrated in propagation maps. During a follow-up of 15.9 +/- 5.9 months, two atrial flutter recurrences occurred (5.8%). A gap of the resumed conduction through the IVC-TA isthmus was delineated as a mechanism of recurrence and ablated with one and three radiofrequency applications. Noncontact mapping allows construction of the global activation patterns in typical and atypical atrial flutter. It enables the nonfluoroscopic guidance of atrial flutter ablation and a comprehensive evaluation of the ablation results.

Pseudotermination of intermittent atrial fibrillation by a pacemaker algorithm: antitachycardia pacing without capture miscounted as successful termination of fibrillation episodes

A patient is described with intermittent AF and an implanted pacemaker which provides preventive pacing and overdrive stimulation designated to terminate atrial arrhythmias. The case highlights the possibility of false estimation of therapeutic efficacy and possible proarrhythmic effect of this therapeutic modality.

Modes of initiation of paroxysmal atrial fibrillation from analysis of spontaneously occurring episodes using a 12-lead Holter monitoring system

Although new, possibly curative radiofrequency ablation techniques for atrial fibrillation (AF) have been developed in recent years, little is known about the mechanisms of spontaneous onset of AF episodes. Using a 12-lead 24-hour Holter monitoring system, we aimed to characterize such episodes. A total of 297 spontaneous episodes of AF in 33 patients with intermittent AF (mean age of 59 +/- 11 years) were analyzed. Two hundred seventy-six episodes (93%) were initiated by atrial premature complexes (APCs), whereas 19 episodes (6.4%) were preceded by typical atrial flutter and 2 (0.7%) by atrial tachycardia. Based on 12-lead electrocardiographic criteria, the origin of ectopic beats initiating AF was classified in 230 episodes (77.5%) as being of left atrial origin, in 6 episodes (2.0%) as being of right atrial origin and in 40 episodes (13.5%) the exact location could not be determined. In 16 of 23 patients (70%) with multiple episodes of AF, ectopic beats that initiated AF were consistently monomorphic. In the 120 seconds (6.2 APCs/min for a 30-second period) before onset of AF, frequency of ectopic beats increased from 0.8 APCs/min in AF-free intervals to 4.1/min (6.2 APCs/min for a 30-second period), (p = 0.003 and p = 0.016, respectively). In 209 of 254 episodes (82%), AF onset occurred during normal sinus rate (60 to 100 beats/min). Thus, paroxysmal AF is triggered most frequently by monomorphic left APCs. In most AF episodes, the increase in the number of ectopic beats that initiated episodes of AF occurred at a normal sinus rate.

Internal atrial defibrillation during electrophysiological studies and focal atrial fibrillation ablation procedures

Induction of sustained AF during electrophysiological studies requires electrical cardioversion to restore sinus rhythm for continuation of the electrophysiological study and mapping procedure. The study included 104 consecutive patients (age 59 +/- 12 years, 74 men), who were in stable sinus rhythm at the beginning of the electrophysiological study, underwent internal atrial defibrillation (IAD) of AF (> 15 minutes) that was induced during electrophysiological study. In 21 patients, AF was regarded to be the clinical problem (group I), and in the remaining 83 patients other arrhythmias represented the primary target of the electrophysiological study (group II). A 7.5 Fr cardioversion catheter (EP Medical) equipped with a distal array was used and placed in the left pulmonary artery and a proximal array of the same size was located along the lateral right atrial wall. All patients were successfully cardioverted with a mean energy of 6.2 +/- 4.0 1. In 18 (78%) of 21 group I patients and in 12 (14%) of 81 group II patients, AF recurred 3.7 +/- 3.4 and 2.4 +/- 1.4 times during electrophysiological study, respectively. The IAD shock did not suppress focal activity, thus the mapping of atrial foci responsible for AF could be continued even after several IADs. No IAD related complications occurred during the study. In conclusion, (1) IAD can be safely and successfully performed during electrophysiological study without using narcotic drugs or high electric energies; (2) IAD does not suppress focal activity; and (3) even if AF recurs frequently during the electrophysiological study, IAD can be performed several times without significant time delay.

Electrophysiologic characteristics of paroxysmal and chronic atrial fibrillation in human right atrium

OBJECTIVES

The aim of the study was to analyze the electrophysiologic characteristics of paroxysmal (PAF) and chronic (CAF) atrial fibrillation (AF) in the human right atrium (RA).

BACKGROUND

Differences that exist between PAF and CAF and the mechanisms of self-sustenance of these arrhythmias are incompletely understood.

METHODS

A total of 53 patients with PAF (25 patients, mean age 59 +/- 6.1 years, 3 women) and CAF (28 patients, mean age 59 +/- 13 years, 7 women) underwent multisite mapping of the RA during ongoing AF using a 64-electrode basket catheter. Quantitative evaluation and three-dimensional activation patterns were performed using a computerized system.

RESULTS

Patients with PAF, as compared with patients with CAF, had significantly longer AF cycle length, shorter time intervals with type III AF throughout the RA and a smaller number of endocardial breakthroughs (mean 51 +/- 19 vs. 104 +/- 40, p < 0.001). The majority of endocardial breakthrough points (88% in PAF patients and 98% in CAF patients) were located in the septal region and coincided anatomically with major interatrial connection routes. Coexistence of re-entrant and apparently focal activation determined maintenance of AF in the RA in PAF, whereas random re-entry was documented more frequently in patients with CAF. In patients with CAF, the duration of arrhythmia (in years) correlated strongly with the percentage of time during which type III AF was observed in the lateral wall of the RA (r = 0.71).

CONCLUSIONS

Clinical PAF and CAF, as recorded in the RA, have, at least quantitatively, distinct electrophysiologic features and different mechanisms of maintenance.

Activation patterns in the left atrium during counterclockwise and clockwise atrial flutter

INTRODUCTION

Activation of the left atrium (LA) in patients with isthmus-dependent right atrial flutter (AFL) has not yet been studied. The aim of this study was to analyze the activation patterns in the LA in patients with counterclockwise and clockwise AFL.

METHODS AND RESULTS

The study population consisted of 12 patients (10 men and 2 women; mean age 61+/-13 years) with documented AFL and atrial fibrillation referred for ablation. The LA was mapped with a 64-electrode basket catheter inserted through a transseptal approach (10 patients) or an open foramen ovale (2 patients). In patients with counterclockwise AFL (10 episodes), the LA was activated for a mean of 133+/-28 msec. Two endocardial breakthroughs of earliest activity on the left side of the interatrial septum, separated in time by an interval of 38+/-15 msec, were observed in 9 episodes (90%). Two wavefronts originated from these breakthroughs, which activated the posterior and the anterior LA walls, respectively. In one patient, the entire LA was activated from the inferior breakthrough. In patients with clockwise AFL (five episodes), the LA activation time was 130+/-13 msec. During ongoing episodes, two early electrical breakthroughs, separated in time by an interval of 41+/-15 msec, appeared in the high anteroseptal and low posteroseptal LA regions. The superior wavefront that emerged from the high anterolateral LA region was the dominant activation pathway in 4 (80%) of 5 episodes.

CONCLUSION

In patients with AFL, the LA is activated by two wavefronts originating from the high anterior and the low posterior regions of the interatrial septum. The sequence of activation of these interatrial connections in counterclockwise or clockwise AFL and the conductive properties of the LA conduction pathways determine the activation patterns in the LA.

Maintenance of sinus rhythm after electrical cardioversion of persistent atrial fibrillation; sotalol vs bisoprolol

AIMS

The purpose of the study was to compare the efficacy and safety of sotalol and bisoprolol in the maintenance of sinus rhythm after electrical cardioversion of atrial fibrillation.

METHODS

Patients (n=128) were randomized to sotalol (80 mg b.i.d.) or bisoprolol (5 mg x day(-1)). Patients with contraindications to beta-blockers, class III antiarrhythmic drugs or prior treatment with use of study medication for prevention of atrial fibrillation were excluded. Follow-up clinical evaluation was performed 1 day and 1 month after cardioversion and thereafter at 3-month intervals.

RESULTS

There were no group differences in baseline clinical characteristics. After a follow-up of 12 months, 59% of all patients were still in sinus rhythm. The fraction remaining in sinus rhythm was calculated for the two groups by Kaplan--Meier analysis. During follow-up, 41% of patients on sotalol and 42% on bisoprolol developed atrial fibrillation (ns). In two patients (3.1%) on sotalol, life-threatening proarrhythmias (torsade de pointes tachycardias) occurred, whereas none were found in the bisoprolol group. Symptomatic bradycardias occurred in two patients on sotalol and three on bisoprolol.

CONCLUSION

This study demonstrates that sotalol (160 mg x day(-1)) and bisoprolol (5 mg x day(-1)) are equally effective in maintaining sinus rhythm. Because of the side effects of sotalol, bisoprolol seems to be advantageous for maintenance of sinus rhythm after cardioversion of atrial fibrillation.

Inappropriate shock delivery due to ventricular double detection with a biventricular pacing implantable cardioverter defibrillator

This report describes a patient with advanced heart failure, pronounced intraventricular conduction delay, and ventricular tachycardias who underwent implantation of a multisite pacing ICD. Pacing leads were placed in the right atrium, right ventricular apex, and to the left ventricular posterior wall via a coronary sinus vein. The system proved to have correct sensing and pacing function in an atrial synchronized biventricular pacing mode and an appropriate detection of ventricular fibrillation. However, 1 month after implantation the patient received an inappropriate shock delivery due to double detection of ventricular premature beats. The inherent detection problem of dual ventricular sensing is discussed.

Dissociation between coronary sinus and left atrial conduction in patients with atrial fibrillation and flutter

INTRODUCTION

Coronary sinus (CS) recordings are routinely used during electrophysiologic studies for various supraventricular and ventricular arrhythmias with the understanding that they represent left atrial (LA) activity. However, the behavior of CS electrical activity during atrial arrhythmias has not drawn any special attention beyond standard considerations.

METHODS AND RESULTS

The study population consisted of 9 patients (3 women; mean age 59 +/- 11 years) with atrial fibrillation (AF) and atrial flutter (AFL) who developed dissociation of conduction between the CS and posterior LA during spontaneous AF and AFL. In all patients, the LA and the CS were mapped using a 64-electrode basket catheter and a multipolar electrode catheter, respectively. The right atrium (RA) was mapped simultaneously using a 24-polar electrode catheter (7 patients) or a 64-electrode basket catheter (2 patients). Eight patients showed stable double potentials in CS recordings during AF (9 episodes) and AFL (3 episodes). During ongoing arrhythmias, the first row of potentials maintained a constant relationship with the RA activity, whereas the second row of potentials was discordant with the posterior wall of the LA in 7 patients and concordant in 2 patients. In 1 patient with counterclockwise AFL, CS activation was isolated from the posterior wall of the RA until it reached the distal portion of the CS, after which it entered the lateral region of the LA. In 1 patient, a macroreentrant LA tachycardia involving CS muscle was observed. Rapid atrial pacing from the proximal CS and extrastimuli produced longitudinal dissociation of CS activation in all patients.

CONCLUSION

Conduction between the CS and posterior LA can be dissociated during spontaneous atrial arrhythmias and provocative proximal CS pacing.

Value of programmed ventricular stimulation for prophylactic internal cardioverter-defibrillator implantation in postinfarction patients preselected by noninvasive risk stratifiers

OBJECTIVES

The aim of this prospective study was to evaluate the role of programmed ventricular stimulation (PVS) after noninvasive risk stratification to identify a subgroup of acute myocardial infarction (AMI) survivors considered at risk for ventricular arrhythmias and whether these patients could benefit from internal cardioverter-defibrillators (ICDs).

BACKGROUND

The predictive value of noninvasive and invasive risk stratifiers after AMI has been questioned. The question of whether the group of patients with inducible monomorphic ventricular tachycardia (VT) after AMI could profit from ICD implantation is unanswered.

METHODS

A consecutive series of 1,436 AMI survivors was screened noninvasively by Holter monitoring, heart rate variability, ventricular late potentials, and ejection fraction. A subgroup of 248 patients (17.3%) were identified as high-risk patients and scheduled for PVS. Due to the study design, 54 patients >75 years were excluded; thus, 194 patients were eligible for PVS. Triple extrastimuli at two paced cycle lengths (600 ms and 400 ms) were applied.

RESULTS

In a subgroup of 98 (51%) high-risk patients, PVS was performed; 21 patients had an abnormal response, and in 20 patients an ICD was implanted. During a mean follow-up of 607 days the arrhythmic event rate (sudden cardiac death, symptomatic VT, cardiac arrest) was 33% with a positive electrophysiological test versus 2.6% (p < 0.0001) with a negative electrophysiological test. A subgroup of 96 high-risk patients declined electrophysiological study. In this nonconsent group, cardiac mortality (combined sudden and nonsudden) was significantly higher (log-rank chi-square 9.38, p = 0.0022, relative risk 4.7, 1.6 to 13.9) compared to the group guided by electrophysiological testing and consecutive ICD implantation.

CONCLUSIONS

After a two-step risk stratification, PVS is helpful in selecting a subgroup of AMI survivors without spontaneous ventricular arrhythmias who benefit from prophylactic ICD implantation.

Reentry circuit location and left atrial three-dimensional activation patterns in left atrial flutter

We report the case of a patient with left atrial flutter (LAF) in whom the reentry circuit location was mapped with a 64-electrode basket catheter deployed in the left atrium. Left atrial three-dimensional activation patterns were constructed with a software program and presented as color-coded isochrones. The reentrant activation traveled preferentially around the mitral annulus in a clockwise direction. It consisted of a single reentry confined anteriorly by the mitral annulus and posteriorly by an anatomic-functional barrier composed of a functional conduction block extending between pulmonary veins and surrounding a part of the posterior wall of the left atrium. The lower portion of the posterior wall and the anterior wall in close proximity to mitral annulus were preferentially used by the reentrant impulse.

Do current dual chamber cardioverter defibrillators have advantages over conventional single chamber cardioverter defibrillators in reducing inappropriate therapies? A randomized, prospective study

INTRODUCTION

Supraventricular tachyarrhythmias are the main cause of inappropriate therapies in patients with conventional single chamber implantable cardioverter defibrillators (VVI-ICD). It was anticipated that dual chamber cardioverter defibrillators (DDD-ICD), with their capacity to analyze atrial and ventricular rhythm, could substantially reduce inappropriate therapies.

METHODS AND RESULTS

Our prospective study included 92 patients (87 men; mean age 61 +/- 12.7 years) who were randomly assigned to a VVI-ICD (45 patients) or a DDD-ICD (47 patients). Both groups were followed for 7.5 +/- 3.5 and 7.6 +/- 4.1 months, respectively. During the follow-up period, overall 725 ventricular tachycardia (VT)/ventricular fibrillation (VF) episodes were recorded in 45 (49%) of 92 patients. Of these episodes, 404 (56%) occurred in the VVI-ICD group and 321 (44%) episodes occurred in the DDD-ICD group. Twenty-three (51%) patients in the VVI-ICD group and 22 (47%) patients in the DDD-ICD group (P = 0.8) developed VT/VF. Overall, 73 (10%) of 725 treated episodes were inappropriate in 6 (13%) patients in the VVI group and in 10 (21%) patients in the DDD-ICD group (P = 0.2). There were 22 (31%) inappropriately treated episodes in the VVI-ICD group and 51 (69%) in the DDD-ICD group. Thirty-two of the 51 inappropriate episodes in the DDD-ICD patients resulted from intermittent atrial sensing problems that led to failure of the respective dual chamber algorithms. Nonfatal complications occurred in 6 (13%) patients in the VVI-ICD group and in 3 (6%) patients in the DDD-ICD group (P = 0.7).

CONCLUSION

We conclude that the implanted DDD-ICD and conventional VVI-ICD are equally safe and effective for therapy of life-threatening ventricular tachyarrhythmias. Although DDD-ICDs allow better rhythm classification, the applied detection algorithms do not offer benefits in avoiding inappropriate therapies during supraventricular tachyarrhythmias.

Acute electrophysiologic effects and antifibrillatory actions of the long linear lesions in the right atrium in a sheep model

Linear lesions (LL) represent an option for curing of atrial fibrillation (AF) with ablation techniques.

METHODS AND RESULTS

In 11 sheep (w. 72+/-16 kg), LL were created with radiofrequency ablation in the lateral, posterior and septal walls of the right atrium (RA). AF was induced before and after LL with burst pacing. Mapping of the AF was performed with a 64-electrode basket catheter deployed in the RA. Quantitative analysis was performed with a custom-made software program. LL were confirmed histologically 7 to 10 days after the procedure. LL were transmural in 78% of their length. Stimulation thresholds and right atrial activation times were increased after LL compared to preablation values. Effective refractory periods of the RA were prolonged significantly in 7 out of 12 regions after generation of LL. Conduction velocities in the RA segments between LL were reduced in lateral, posterior and septal walls. During paced rhythms double potentials were recorded in all animals. AF could be induced in all animals of this model despite the presence of LL in the RA. AF episodes were significantly more regular after LL throughout the RA due to a significant reduction of the number of the wave fronts in the RA. During AF episodes, in the presence of LL, the RA was driven by wave fronts of left atrial origin entering the right side of the septum through interatrial connections.

CONCLUSIONS

1) LL profoundly affect electrophysiologic parameters of RA. 2) In the presence of LL, AF manifest a higher degree of regularity as compared to preablation episodes. 3) Dissociation between wave fronts of left atrial origin entering the RA through the interatrial connections is an important mechanism of the antifibrillatory action of the septal LL.

Basket catheter-guided three-dimensional activation patterns construction and ablation of common type atrial flutter

Construction of three-dimensional activation maps and evaluation of ablation-created bidirectional block in the tricuspid valve-inferior vena caval (TV-IVC) isthmus in patients with atrial flutter (AF) are difficult with conventional mapping technique. In 36 patients with type I AF (25 men, 11 women; mean age 62 +/- 10.5 years) a multielectrode basket catheter (BC) was deployed in the right atrium (RA). Out of 64 BC electrodes, 56 bipolar electrograms were derived. Three-dimensional activation patterns were constructed with a software program. Stable electrograms of satisfactory quality were obtained in 49 +/- 2 electrode pairs. Capture was possible in 36 +/- 3 of bipoles. In counterclockwise AF (CCW-AF) and clockwise AF (CW-AF) episodes, cycle lengths and TV-IVC isthmus conduction times were 248 +/- 26 ms and 251 +/- 23 ms, (P = 0.74) and 105 +/- 28 ms and 106 +/- 33 ms (P = 0.92), respectively. Conduction velocity in the TV-IVC isthmus was lower than in the anterior or septal limbs of the circuit, in counterclockwise or clockwise episodes. Double potentials were recorded in 94% of patients. Three-dimensional activation patterns were delineated and displayed as isochronal maps. The reentry circuit involved the TV-IVC isthmus, septal, and anterior walls and a part of the RA roof anterior to superior vena cava. Postablation isthmus conduction was evaluated through the sequence criteria, local electrogram-based criteria, and the analysis of three-dimensional activation patterns of the paced rhythms. The complete isthmus block was associated with a significant increase of the low anterior low septal conduction interval (152 +/- 29 vs 104 +/- 32 ms, P = 0.001) and the low septal-low anterior conduction interval (150 +/- 31 vs 107 +/- 33 ms, P = 0.001). Radiofrequency ablation was successful in 32 (90%) of 36 patients. In conclusion, the current mapping system enables construction of three-dimensional activation patterns and facilitates evaluation of the postablation TV-IVC isthmus block in patients with AF.

ECG changes in a 25-year-old woman with hypocalcemia due to hypoparathyroidism. Hypocalcemia mimicking acute myocardial infarction

The case of a 25-year-old woman presenting with chest pain, ECG changes, and laboratory findings suggestive of myocardial infarction is reported. Cardiac catheterization showed impaired left ventricular performance but otherwise normal coronary arteries. Laboratory analyses revealed primary hypoparathyroidism, and supplementation with calcium and vitamin D(3) was initiated. There was subsequent improvement in laboratory findings as well as echocardiographically determined left ventricular performance. Thereafter, the patient remained asymptomatic. Apart from some persisting ECG repolarization disturbances, there was complete normalization of the initial changes. This case demonstrates a combination of clinical, blood biochemical, and ECG findings mimicking acute myocardial infarction.

Relationship between surface electrocardiogram characteristics and endocardial activation sequence in patients with typical atrial flutter

OBJECTIVES

The relationships that exist between endocardial and surface electrocardiogram (ECG) activity in patients with AFl have not been satisfactorily delineated. The aim of the study was to determine the relationships that exist between the atrial endocardial activity and the surface ECG in patients with atrial flutter (AFl).

METHODS

In 40 patients with AFl, a 64-electrode basket catheter (BC) was deployed in the right atrium (RA). A decapolar catheter was inserted into the coronary sinus (CS) to record from the left atrium. The temporal relationship between endocardial and surface ECG activity was determined by means of electronic calipers.

RESULTS

In counterclockwise AFl, the activation of the lateral wall of RA coincided with the positive deflections in lead I, V1 and V6 and the upstroke component in inferior leads. Plateau duration in lead III (121 +/- 27 ms) correlated strongly with isthmus conduction time (117 +/- 23 ms) (r = 0.91). Septal and left atrial conduction coincided with negative components in lead I, inferior leads and V6 and positive deflections in leads aVL and V1. In clockwise AFl, the F wave was notched in all ECG leads. The first component resulted from the activation of the septum and posterior wall of the RA. The second component was coincident with activity recorded in CS electrograms. The interval between the two deflections (60 +/- 18 ms) correlated strongly with interatrial conduction time (57 +/- 19 ms) (r = 0.84). Interatrial conduction interval was prolonged during AFl as compared to sinus rhythm (60 +/- 18 ms vs 43 +/- 13 ms, p = 0.04). Activation of the lateral wall of RA coincided with the negative components in lead I, inferior leads and V6.

CONCLUSIONS

The electrical activity in surface ECG closely correlates with conduction in specific parts of the atria. Polarity of the F wave in an ECG lead is determined by a resultant of opposing activities from the lateral wall of the RA and the left atrium.

Left atrial fibrillation with regular right atrial activation and a single left-to-right electrical interatrial connection: multisite mapping of dissimilar atrial rhythms

We report two patients who had isolated atrial fibrillation in the left atrium and regular activation of the entire right atrium. Mapping of the arrhythmia was performed using a 64-electrode basket catheter that was inserted intravenously and deployed in the right and left atria. Both patients manifested a single, stable interatrial electrical connection conducting in a left-to-right direction, consistent with Bachmann's bundle location. The right and left sides of the interatrial septum were activated discordantly, each reflecting activation characteristics of the respective atria. A filtering effect at the level of interatrial septum was demonstrated by calculating the fibrillation intervals on both sides of the operative interatrial connection. It was concluded that differences in activation of the left and right surfaces of the interatrial septum and preferential use and the filtering effect of the interatrial connections play a significant role in explaining the differences in activation patterns of the left and right atria in patients with atrial fibrillation.

Block of the lower interatrial connections: insight into the sources of electrocardiographic diversities in common type atrial flutter

Whether the conduction disturbances of the interatrial connections play a role in the genesis of ECG variants of atrial flutter is almost completely unknown. We present a patient with typical counterclockwise atrial flutter in whom the ablation of the coronary sinus (CS) area during ongoing atrial flutter produced significant ECG changes without alterations in the activation sequence within the right atrium (RA). This case highlights the possible role of alterations of the interatrial connections in the genesis of atypical ECG manifestations of common type atrial flutter.

Noncontact mapping-guided catheter ablation of atrial fibrillation associated with left atrial ectopy

We report the use of a novel noncontact mapping system used to perform left atrial mapping and to guide radiofrequency ablation in two patients, each with atrial fibrillation (AF) triggered by left atrial ectopy. A noncontact multielectrode probe and ablation catheter were advanced into the left atrium through a transseptal puncture or a patent foramen ovale. Isopotential mapping delineated the focal origin at the ostium of the right lower pulmonary vein in one patient and close to the ostium of the left upper pulmonary vein in the other patient. The ablation catheter was guided to the target sites using a locator signal. The foci were ablated successfully in both patients. No recurrences of AF were observed during follow-up at 4 and 6 months, respectively.

The recording of monophasic action potentials with fractal-coated iridium electrodes in humans

The present study was designed to evaluate the feasibility of the recording of monophasic action potentials (MAP) with fractal-coated iridium electrodes in a clinical setting. In 18 patients who underwent an electrophysiological study for various arrhythmias, we performed MAP recordings with both 1.3-mm2 and 6-mm2 tip surface area fractal-coated iridium and standard silver--silver chloride (Ag/AgCl) electrodes in the high right atrium and two ventricular positions. Amplitude and MAP duration at 90%, 50%, and 25% of repolarization were calculated during steady-state pacing at 600, 500, and 400 ms cycle lengths with extrastimuli application. Morphology comparisons of MAP signals recorded with both types of electrodes were performed by regression analysis using 5% of the repolarization segments of the MAP trajectory. Differences between MAP duration at 90%, 50%, and 25% of repolarization recorded with fractal-coated and Ag/AgCl electrodes were statistically insignificant. Amplitude values recorded with 6-mm2 tip electrodes were significantly smaller than those recorded with Ag/AgCl electrodes for all comparisons. During steady-state pacing, the correlation coefficients between Ag/AgCl and fractal-coated 1.3-mm2 and 6-mm2 tip electrodes were within the range of 0.93-0.999 and 0.87-0.999, respectively. The correlation of MAP amplitude and duration at 90%, 50%, and 25% of repolarization following the extrastimulus S2, recorded with both types of electrodes, was significantly weaker for right atrial recordings (r value range 0.78-0.92) as compared to ventricular recordings (r value range 0.92-0.99). The MAP sensing features of fractal-coated iridium and Ag/AgCl electrodes are comparable. The best results for recording of MAPs with fractal-coated electrodes can be achieved with small surface area tip electrodes.

Computer-assisted animation of atrial tachyarrhythmias recorded with a 64-electrode basket catheter

OBJECTIVES

The aim of this study was to assess the value of a new mapping technique based on computer-assisted animation of multielectrode basket catheter (BC) recordings in patients with atrial arrhythmias.

BACKGROUND

The three-dimensional activation patterns of cardiac arrhythmias are not completely understood owing to limitations of conventional mapping techniques.

METHODS

The study included 32 patients with atrial tachycardia (AT) and 38 patients with atrial flutter (AFL). A software program was developed to analyze the activation patterns based on 56 bipolar electrograms recorded with a 64-electrode BC deployed in the right atrium (RA).

RESULTS

The total time needed for the animation of activation patterns of atrial arrhythmias was 5 +/- 0.8 min. In 22 patients with right AT, the animated maps revealed that arrhythmia was unifocal in 15 patients, multifocal in 2 patients, polymorphic in 4 patients and reentrant in 1 patient. In 10 patients with left AT, breakthroughs on the right side of the septum (2 in 8 patients and 1 in 2 patients) and a left-to-right activation of the RA were demonstrated. In patients with typical AF, the reentrant excitation was a broad activation front with preferential propagation around the tricuspid annulus. In patients with atypical AFL, the reentry circuit involved one of the venae cavae and a line of block located in the posterior wall.

CONCLUSIONS

The computer-assisted animation of multiple electrograms recorded with a BC is a valuable mapping tool that delineates the three-dimensional activation patterns of various atrial arrhythmias. The technique is appropriate for complex, short-lived or unstable arrhythmias.

Recent advances in cardiac mapping techniques

Recently several new mapping modalities have been introduced into clinical electrophysiologic laboratories, including basket catheter mapping, electromagnetic mapping, and noncontact mapping. In addition, intracardiac echocardiography is being used increasingly to visualize important intracardiac structures for catheter ablation. Basket catheter mapping and noncontact mapping are simultaneous mapping devices, whereas electromagnetic mapping is a sequential mapping tool. The new basket-shaped catheters provide up to 64 electrodes mounted on a variable number of splines that encircle the cardiac contour. Animation programs help in identifying the earliest activation and analyzing the activation sequence. Electromagnetic mapping uses low density magnetic fields to navigate the catheter position and to allow nonfluoroscopic mapping and ablation. Sequential recording of intracardiac potentials produces a real-time, color-coded, three-dimensional activation map. Noncontact mapping does not require direct contact with the endocardium and permits the reconstruction of more than 3000 simultaneous computed electrograms via mathematical algorithms. Three-dimensional isopotential maps are generated to visualize the impulse propagation and guide catheter ablation.

Clinical experience with a novel multielectrode basket catheter in right atrial tachycardias

BACKGROUND

The complexity of atrial tachycardias (ATs) makes the electroanatomic characterization of the arrhythmogenic substrate difficult with conventional mapping techniques. The aim of our study was to evaluate possible advantages of a novel multielectrode basket catheter (MBC) in patients with AT.

METHODS AND RESULTS

In 31 patients with AT, an MBC composed of 64 electrodes was deployed in the right atrium (RA). The possibility of deployment, spatial relations between MBC and RA, MBC recording and pacing capabilities, mapping performance, and MBC-guided ablation were assessed. MBC deployment was possible in all 31 patients. The MBC was left in the RA for 175+/-44 minutes. Stable bipolar electrograms were recorded in 88+/-4% of electrodes. Pacing from bipoles was possible in 64+/-5% of electrode pairs. The earliest activity intervals, in relation to P-wave onset, measured from the MBC and standard roving catheters were 41+/-9 and 46+/-6 ms, respectively (P=0.21). Radiofrequency ablation was successful in 15 (94%) of 16 patients in whom it was attempted, including 2 patients with polymorphic right atrial tachycardia (RAT), 2 with RAT-atrial flutter combination, 1 with macroreentrant AT, and 1 with focal origin of atrial fibrillation.

CONCLUSIONS

These data demonstrate that MBC can be used safely in patients with right atrial arrhythmias. The simultaneous multielectrode mapping aids in the rapid identification of sites of origin of the AT and facilitates radiofrequency ablation procedures. The technique is especially effective for complex atrial arrhythmias.

The influence of pacing rate and autonomic blockade on human primary and secondary atrial pacemakers

The morphology of the first spontaneous post-pacing P wave was assessed in 106 patients who underwent electrophysiological study for various arrhythmias. An overall number of 589 atrial pacing sessions, from 60-200 b/min, were analyzed (mean 5.55 +/- 1.3 session per patient). After cessation of 138 (23.42%) of them, spontaneous post-pacing P wave arose from extrasinus foci. Nonsinus spontaneous post-pacing P waves were recorded after 1 or more pacing rates (from 1 to 7) in 58 patients (54.7%, Group 1). In the remaining 48 patients the spontaneous post-pacing P waves were sinus after all pacing sessions (45.3%, Group 2). Sinus node disease (SND) was present in 32.7% of Group 1 patients and in 2% of Group 2 (p = 0.002). Spontaneous post-pacing P wave of extrasinus origin was recorded in 19/20 of SND patients (95%) compared to 39/86 of patients with normal sinus function (45.34%, p < 0.001). SND patients had a greater number of pacing sessions resulting in nonsinus spontaneous post-pacing P waves. Pacing rate associated with nonsinus spontaneous post-pacing P waves was lower in SND patients compared to patients with normal sinus node function. In the SND group, nonsinus spontaneous post-pacing P waves were recorded beyond the first spontaneous one in 9 patients compared to only 1 in patients with normal sinus node function (p < 0.005). Extrasinusal first spontaneous post-pacing P waves at a pacing rate of 140 b/min had the highest sensitivity (75%). Increasing of pacing rate from 60 to 140 b/min was associated with progressive arousal of secondary foci with highest value of 36.8% in pacing rate of 140 b/min. Further increase of pacing rate resulted in a slight reduction of spontaneous post-pacing firing from secondary foci. Atropine was administered in 12 Group 1 patients and abolished all measurable morphological changes of spontaneous post-pacing P waves compared to pre-pacing. Autonomic blockade was performed in 14 Group 1 patients and 16 Group 2 patients. In 35.7% of Group 1 patients autonomic blockade abolished the appearance of nonsinus spontaneous post-pacing P waves, while in the remaining patients increased the lowest pacing rate resulting in nonsinus spontaneous post-pacing P waves. In 12.5% Group 2 patients autonomic blockade resulted in nonsinus spontaneous post-pacing P waves after cessation of atrial pacing. In conclusion, the extrasinus spontaneous rise of atrial impulse is a very frequent phenomenon after atrial pacing especially in patients with SND. Pacing rate has different quantitative effects on sinus and secondary atrial pacemakers. Secondary pacemakers are less under autonomic control compared to sinus node.

Actions of lidocaine on reentrant ventricular rhythms in the subacute myocardial infarction period in dogs

The actions of lidocaine were studied in 18 dogs, 4 days after ligation of the left anterior descending artery, by computerized mapping. Lidocaine only occasionally suppressed the induction of reentry. At fast heart rates, lidocaine actually facilitated the induction of reentry. The effects on conduction and refractoriness of normal and ischemic myocardium were measured using high-resolution techniques. Lidocaine promoted reentry by a rate-dependent increase in refractory gradient, resulting in additional block, and a selective decrease in conduction velocity in ischemic tissue, resulting in additional conduction delay. Lidocaine could prevent reentry through a rate-independent differential increase in refractory period gradient at the entrance to the common pathway of the circuit, causing block of the reentrant impulse. We conclude that the proarrhythmic effect of lidocaine is due to increased conduction delay and block while the antiarrhythmic effect is due to block of the reentrant impulse by prolonged refractoriness in the common pathway.

Activation time determination by high-resolution unipolar and bipolar extracellular electrograms in the canine heart

INTRODUCTION

To identify the optimal criteria for activation time (AT) determination of bipolar electrograms from normal hearts, a high-resolution cross electrode array comprising 128 unipolar electrodes of 500-microns spacing was used to record extracellular potentials from the left ventricular epicardium of 12 dog hearts.

METHODS AND RESULTS

Recordings were made during broad wavefront propagation (B wave) and local elliptical wavefront propagation (E wave). Characteristics of 863 bipolar electrograms (1-mm spacing) were constructed from unipolar data standardized for differences in polarity, then classified morphologically. Features for bipolar AT determination were compared to the time of the negative peak of the first temporal derivative of a unipolar electrogram situated mid-way between the bipoles. During B wave, three distinct morphologies were observed: uniphasic (61%), biphasic (23%), and triphasic (16%). Peak voltage of uniphasic and triphasic signals was the best predictor of AT (error: 0.6 +/- 0.6 msec and 0.6 +/- 0.8 msec, respectively). During E wave, parallel orientation of the bipoles with respect to the direction of impulse propagation wavefront resulted in uniphasic signals (> 99%), while for perpendicular orientation of the bipoles, electrogram morphology was variable. For parallel orientation of the bipoles, peak negative voltage was the best predictor of AT for both longitudinal and transverse propagation, while for perpendicular bipole orientation, peak negative voltage was a less reliable predictor for propagation along both fiber axes. Increasing interpolar distance resulted in a degradation in AT accuracy for B wave (from 0.6 +/- 0.6 msec at 1 mm to 1.1 +/- 1.2 msec at 7 mm) and for E wave (from 0.4 +/- 0.3 msec at 1 mm to 3.1 +/- 2.9 msec at 7 mm).

CONCLUSIONS

(1) The accuracy of bipolar electrograms is sensitive to wavefront direction, bipole orientation, and interpolar distance; (2) peak negative voltage of uniphasic and triphasic signals is a reliable predictor of AT, but only for B wave; (3) a maximum interpolar distance of 2 mm and bipole orientation parallel to the direction of the impulse wavefront are minimally required for accurate determination of AT during impulse propagation initiated near the recording electrodes; and (4) for impulses initiated near the recording site in normal tissue, a biphasic or triphasic morphology almost certainly indicates that the bipolar electrode is oriented perpendicular to the wavefront direction, irrespective of fiber orientation.

Reentrant arrhythmias in the subacute infarction period. The proarrhythmic effect of flecainide acetate on functional reentrant circuits

BACKGROUND

The Cardiac Arrhythmia Suppression Trial has shown that flecainide was associated with an increased incidence of sudden cardiac death in postinfarction patients. The exact mechanism(s) of the proarrhythmic effects of flecainide remain unclear. We performed a detailed analysis of the electrophysiological and proarrhythmic effects of flecainide in a well-characterized model of reentrant arrhythmias in the subacute phase of myocardial infarction.

METHODS AND RESULTS

Sixteen dogs were studied 4 days after ligation of the left anterior descending coronary artery. Isochronal mapping of ventricular activation showed that flecainide facilitated both the induction and sustenance of ventricular tachycardia, especially at shorter basic cycle lengths. Flecainide had negligible effect on the length of the arc of functional conduction block but markedly depressed conduction of the common reentrant wave front that was usually oriented parallel to fiber axis. Whole heart mapping was analyzed in combination with basic measurements of the effects of flecainide on conduction and refractory properties of both normal and ischemic myocardia using a high-resolution cross electrode consisting of four orthogonal arms, each comprised of 16 poles with an interelectrode spacing of 500 microns. The electrode was especially designed to study the effects of the drug on anisotropic conduction as determined by a linear regression of activation time and distance in each direction. Flecainide resulted preferentially in more marked rate-dependent depression of conduction in ischemic compared with normal myocardium. On the other hand, the effect of flecainide on refractoriness in both normal and ischemic myocardia was negligible.

CONCLUSIONS

Because flecainide caused no significant change in refractoriness in both normal and ischemic myocardia, there was no difference in the dimension of the potential reentrant pathway, that is, the continuous line of functional conduction block, around which the reentrant wave fronts circulate. Yet, flecainide resulted in significant rate-dependent slowing of conduction preferentially in ischemic myocardium. The additional slowing of conduction of the common reentrant wave front coupled with minimal changes in the length of the reentrant pathway allowed additional time for the wave front to reexcite normal myocardium on the proximal side of the arc of block. After flecainide, reentry could be induced in hearts in which reentry could not be induced during control. The same proarrhythmic mechanism explains the propensity of nonsustained figure-8 reentrant tachycardias to become sustained after flecainide.