Nonprocedural bleeding after left atrial appendage closure versus direct oral anticoagulants: A subanalysis of the randomized PRAGUE-17 trial

INTRODUCTION

Observational studies have shown low bleeding rates in patients with atrial fibrillation (AF) treated by left atrial appendage closure (LAAC); however, data from randomized studies are lacking. This study compared bleeding events among patients with AF treated by LAAC and nonvitamin K anticoagulants (NOAC).

METHODS

The Prague-17 trial was a prospective, multicenter, randomized trial that compared LAAC to NOAC in high-risk AF patients. The primary endpoint was a composite of a cardioembolic event, cardiovascular death, and major and clinically relevant nonmajor bleeding (CRNMB) defined according to the International Society on Thrombosis and Hemostasis (ISTH).

RESULTS

The trial enrolled 402 patients (201 per arm), and the median follow-up was 3.5 (IQR 2.6-4.2) years. Bleeding occurred in 24 patients (29 events) and 32 patients (40 events) in the LAAC and NOAC groups, respectively. Six of the LAAC bleeding events were procedure/device-related. In the primary intention-to-treat analysis, LAAC was associated with similar rates of ISTH major or CRNMB (sHR 0.75, 95% CI 0.44-1.27, p = 0.28), but with a reduction in nonprocedural major or CRNMB (sHR 0.55, 95% CI 0.31-0.97, p = 0.039). This reduction for nonprocedural bleeding with LAAC was mainly driven by a reduced rate of CRNMB (sHR for major bleeding 0.69, 95% CI 0.34-1.39, p = .30; sHR for CRNMB 0.43, 95% CI 0.18-1.03, p = 0.059). History of bleeding was a predictor of bleeding during follow-up. Gastrointestinal bleeding was the most common bleeding site in both groups.

CONCLUSION

During the 4-year follow-up, LAAC was associated with less nonprocedural bleeding. The reduction is mainly driven by a decrease in CRNMB.

Bimodal distribution of QRS complex duration in patients with dilated cardiomyopathy undergoing an ICD implant procedure

Background/Introduction

In patients with heart failure with reduced ejection fraction (HFrEF), QRS duration is of the uttermost importance. Substantial proportion of patients with HFrEF and sufficiently prolonged QRS complex, especially those with left bundle branch block (LBBB), may significantly benefit from cardiac resynchronization therapy.

Purpose

The aim of the study was to analyse the distribution of the QRS durations in patients with HFrEF undergoing ICD implant procedure to better understand the phenomenon of QRS prolongation.

Methods

All patients undergoing the implant procedure in our centre between January 2017 and December 2021 for HFrEF caused by coronary artery disease (CAD) or dilated cardiomyopathy (DCM) were analysed for the inclusion into the study. The exclusion criteria were (1) coincidence of CAD with DCM, (2) upgrade from any other cardiac rhythm management device, (3) unavailability of the ECG recording or ECG recording with insufficient quality before the implant procedure, (4) more than one ventricular premature beat in the recording. The study used automatically measured QRS duration by Mortara EKG machines (299 recordings with ELI350, 98 with ELI380, and 10 with ELI250). Statistical analysis was performed in R software [1] with the function locmodes for the visualisation of probability density and excess mass test [2] for assessing statistical significance, both from the multimode package.

Results

The study included 407 patients. In 113 patients with DCM and 177 patients with CAD, the implantation was based on primary prevention (PP) indications, and 24 and 93 patients with DCM and CAD were implanted for secondary prevention (SP) indications. The distribution of QRS durations in the CAD-PP, as well as CAD-SP was unimodal (p=ns). In the DCM-PP group, the distribution was bimodal (p=0.012), in the DCM-SP group, the trend was non-significantly bimodal (p=0.076). Both DCM groups taken together had clearly bimodal distribution (p=0.002 – probability density curve according to locmodes function in the figure). The values between 139 and 142 ms were not present in this group. Below this border zone, two other patients fulfilled the criteria of LBBB, both with the duration close to the border zone (137 and 138 ms). Above this zone, 8 patients had right bundle branch block, the rest had LBBB.

Conclusions

Bimodal distribution of QRS duration values in patients with DCM supports the idea of sudden change of left bundle conduction rather than slow progression of local changes. In CAD, scars and other local impairments in conduction may hide these changes and no clear border zone can be set. With the well-known differences in the measurements of main ECGmachine manufacturers, criteria for bundle branch block in DCM could be set with high accuracy.

Funding Acknowledgement

Type of funding sources: Public grant(s) – National budget only. Main funding source(s): Charles University Research Program “Cooperatio – Cardiovascular Science” and the Ministry of Health of the Czech Republic Conceptual Development of Research Organization

Left Atrial Appendage Closure versus Non-Warfarin Oral Anticoagulation in Atrial Fibrillation: 4-Year Outcomes of PRAGUE-17

BACKGROUND

The PRAGUE-17 trial demonstrated that left atrial appendage closure (LAAC) was non-inferior to non-warfarin oral anticoagulants (NOAC) for preventing major neurological, cardiovascular or bleeding events in high-risk patients with atrial fibrillation (AF).

OBJECTIVE

To assess the pre-specified long-term (4-year) outcomes in PRAGUE-17.

METHODS

PRAGUE-17 was a randomized non-inferiority trial comparing percutaneous LAAC (Watchman or Amulet) with NOACs (95% apixaban) in non-valvular AF patients with a history of cardioembolism, clinically-relevant bleeding, or both CHA₂DS₂-VASc > 3 and HASBLED > 2. The primary endpoint was a composite of cardioembolic events (stroke, transient ischemic attack, or systemic embolism), cardiovascular death, clinically-relevant bleeding, or procedure/device-related complications (LAAC group only). The primary analysis was modified intention-to-treat (mITT).

RESULTS

We randomized 402 AF patients (201 per group, age 73.3±7.0 years, 65.7% male, CHA₂DS₂-VASc 4.7+1.5, HASBLED 3.1+0.9). After 3.5 years median follow-up (1,354 patients-years), LAAC was non-inferior to NOAC for the primary endpoint by mITT (subdistribution hazard ratio[sHR] 0.81, 95% CI 0.56-1.18; p=0.27; p for non-inferiority=0.006). For the components of the composite endpoint, the corresponding sHRs (and 95% CIs) were 0.68 (0.39-1.20; p=0.19) for cardiovascular death, 1.14 (0.56-2.30; p=0.72) for all-stroke/TIA, 0.75 (0.44-1.27; p=0.28) for clinically-relevant bleeding, and 0.55 (0.31-0.97; p=0.039) for non-procedural clinically-relevant bleeding. The primary endpoint outcomes were similar in the per-protocol [sHR 0.80 (95% CI 0.54-1.18), p=0.25] and on-treatment [sHR 0.82 (95% CI 0.56-1.20), p=0.30] analyses.

CONCLUSION

In long-term follow-up of PRAGUE-17, LAAC remains non-inferior to NOACs for preventing major cardiovascular, neurological or bleeding events. Furthermore, non-procedural bleeding was significantly reduced with LAAC.

Cardiac Resynchronization and Defibrillator Therapy (CRT-D) or CRT Alone (CRT-P) in patients with dilated cardiomyopathy and heart failure without late gadolinium enhancement (LGE) cardiac magnetic resonance imaging (CMRI) high-risk markers - CRT-REALITY study - Study design and rationale

BACKGROUND

Primary preventive implantation of implantable defibrillator (ICD) is according to current guidelines indicated in patients with heart failure NYHA (New York Heart Association) class II/III and LVEF <35%. Thanks to advances in heart failure pharmacotherapy, a decrease in mortality could render a benefit of ICD insufficient to justify its implantation in some patients.

METHODS

Study design: multicenter, prospective, randomized, controlled trial evaluating the benefit of implantation of Cardiac Resynchronization and Defibrillator Therapy (CRT-D) or CRT Alone (CRT-P) in non-ischemic patients with reduced left ventricle ejection fraction (LVEF) and optimal pharmacotherapy without significant mid-wall myocardial fibrosis detected by cardiac magnetic resonance (CMR). The primary end-point: Re-hospitalization for heart failure, ventricular tachycardia, major adverse cardiac events (MACE). The secondary end-points: Sudden cardiac death, cardiovascular death, resuscitated cardiac arrest or sustained ventricular tachycardia, device-related complications, and change in quality of life. Course of the study: After a pharmacotherapy is optimized and significant mid-wall myocardial fibrosis excluded, patients will be randomized 1:1 to CRT-P or CRT-D implantation.

DISCUSSION

If our hypothesis is confirmed, this could provide evidence for the management of these patients with a significant impact on common daily praxis and health care expenditures.

TRIAL REGISTRATION

ClinicalTrials.gov, NCT04139460.

The variability of automated QRS duration measurement

Aims

Previous studies have demonstrated substantial variability in manual assessment of QRS complex duration (QRSd). Disagreements in QRSd measurements were also found in several automated algorithms tested on digitized electrocardiogram (ECG) recordings. The aim of our study was to investigate the variability of automated QRSd measurements performed by two commercially available electrocardiographs.

Methods and Results

Two GE MAC 5000 (GE-1 and GE-2) electrocardiographs and two Mortara ELI 350 (Mortara-1 and Mortara-2) electrocardiographs were used in the study. Participants for the study were recruited from patients hospitalized in the department of cardiology of a university hospital. Participants underwent up to four recording sessions within a single day with a different electrocardiograph at each session when two to four immediately successive ECG recordings were undertaken. In 76 patients, 683 ECGs were recorded; the mean QRSd was 109.0 ± 26.1 ms. The QRSd difference ≥10 ms between the first and second intra-session ECG was found in 7, 3, 20, and 14% of ECG pairs for GE-1, GE-2, Mortara-1, and Mortara-2, respectively. No inter-session difference in QRSd was found within both manufacturers. In individual patients, Mortara calculated the mean QRSd to be longer by 7.3 ms (95% CI: 6.2-8.5 ms, P < 0.0001) with a 2.1-times (95% CI: 1.9-2.4) greater standard deviation of the mean QRSd (7.1 vs. 3.3 ms, P < 0.001).

Conclusion

Electrocardiographs from two manufacturers measured QRSd values with a systematic difference and a significantly different level of precision. This may have important clinical implications in selection of suitable candidates for cardiac resynchronization therapy.

Interventional left atrial appendage closure vs novel anticoagulation agents in patients with atrial fibrillation indicated for long-term anticoagulation (PRAGUE-17 study)

Atrial fibrillation (AF), with a prevalence of 1% to 2%, is the most common cardiac arrhythmia. Without antithrombotic treatment, the annual risk of a cardioembolic event is 5% to 6%. The source of a cardioembolic event is a thrombus, which is usually formed in the left atrial appendage (LAA). Prevention of cardioembolic events involves treatment with anticoagulant drugs: either vitamin K antagonists or, recently, novel oral anticoagulants (NOAC). The other (nonpharmacologic) option for the prevention of a cardioembolic event involves interventional occlusion of the LAA.

OBJECTIVE

To determine whether percutaneous LAA occlusion is noninferior to treatment with NOAC in AF patients indicated for long-term systemic anticoagulation.

STUDY DESIGN

The trial will be a prospective, multicenter, randomized noninferiority trial comparing 2 treatment strategies in moderate to high-risk AF patients (ie, patients with history of significant bleeding, or history of cardiovascular event(s), or a with CHA₂DS₂VASc ≥3 and HAS-BLED score ≥2). Patients will be randomized into a percutaneous LAA occlusion (group A) or a NOAC treatment (group B) in a 1:1 ratio; the randomization was done using Web-based randomization software. A total of 396 study participants (198 patients in each group) will be enrolled in the study. The primary end point will be the occurrence of any of the following events within 24months after randomization: stroke or transient ischemic attack (any type), systemic cardioembolic event, clinically significant bleeding, cardiovascular death, or a significant periprocedural or device-related complications.

CONCLUSION

The PRAGUE-17 trial will determine if LAA occlusion is noninferior to treatment with NOAC in moderate- to high-risk AF patients.

Catheter ablation of electrical storm in patients with structural heart disease

AIMS

Electrical storm (ES) adversely affects prognosis of patients and may become a life-threatening event. Catheter ablation (CA) has been proposed for the treatment of ES. Our goal was to evaluate the efficacy of CA ablation both in acute and long-term suppression of ES.

METHODS AND RESULTS

Fifty consecutive patients with coronary artery disease (38), idiopathic dilated cardiomyopathy (5), arrhythmogenic right ventricular cardiomyopathy (6), and/or with combined aetiology (1) underwent CA for ES. Mean left ventricular ejection fraction (LVEF) was 29 ± 11%. All patients underwent electroanatomical mapping, and CA was performed to abolish all inducible ventricular arrhythmias. The ES was suppressed by CA in 84% of patients. During the follow-up of 18 ± 16 months, 24 patients had no recurrences of any ventricular tachycardia (VT; 48%). Repeated procedure was necessary to suppress the recurrent ES in 13 cases (26%). Statistical analysis revealed that low LVEF (22 ± 3 vs. 31 ± 12%; P < 0.001), increased LVend-diastolic diameter (72 ± 9.1 vs. 64 ± 8.9 mm; P = 0.0135), and renal insufficiency (P < 0.001) were the univariate predictors of early mortality or necessity for heart transplantation. Recurrence of ES despite previous CA procedure was associated with a higher risk of death or heart transplant during follow-up (P < 0.05).

CONCLUSION

Catheter ablation is effective in acute suppression of ES and often represents a life-saving therapy. In the long term, it prevents recurrences of any VT in about half of the treated patients.

Catheter ablation of arrhythmic storm triggered by monomorphic ectopic beats in patients with coronary artery disease

BACKGROUND

Frequent episodes of polymorphic ventricular tachycardias/ventricular fibrillation (VT/VF) in patients with coronary artery disease can be triggered by monomorphic ventricular premature beats (VPBs) and thus, amenable to catheter ablation. The goal of this study was to review single-center experience in catheter ablation of electrical storm caused by focally triggered polymorphic VT/VF.

METHODS

Catheter ablation of electrical storm due to focally triggered polymorphic VT/VF was performed in nine patients (mean age, 62+/-7 years; two females). All patients had previous myocardial infarction (interval of 3 days to 171 months). Mean left ventricular ejection fraction was 27+/-6 percent. All patients presented with repeated runs of polymorphic VT/VF triggered by monomorphic VPBs.

RESULTS

Based on mapping data, the ectopic beats originated from scar border zone on interventricular septum (n=5), inferior wall (n=3), and lateral wall (n=1). Catheter ablation was performed to abolish the triggering ectopy and to modify the arrhythmogenic substrate by linear lesions within the infarct border zone. The ablation procedure was acutely successful in eight out of nine patients. During the follow-up of 13+/-7 months, two patients died due to progressive heart failure. One patient had late recurrence of electrical storm due to ectopic beats of different morphology and was successfully reablated.

CONCLUSION

Electrical storm due to focally triggered polymorphic VT/VF may occur either in subacute phase of myocardial infarction or substantially later after index event. Catheter ablation of ectopic beats triggering these arrhythmias can successfully abolish electrical storm and become a life-saving procedure.

Life-threatening arrhythmia caused by primary aldosteronism

BACKGROUND

Arrhythmias are one of the typical complications of primary aldosteronism (PA), is commonly characterized by hypertension and hypokalemia.

CASE REPORT

In this report, we present 3 cases of subjects in whom primary aldosteronism manifested with life-threatening arrhythmias. In 2 subjects, after excluding organic heart disease, an implantable cardioverter defibrillator was inserted and, only after the second episode of polymorphic ventricular tachycardia accompanied with low plasma potassium levels, the diagnosis of primary aldosteronism was made.

CONCLUSIONS

It is important to include diagnosis of primary aldosteronism in the diagnostic work-up of hypertensive subjects without any structural cardiovascular impairment who present with malignant arrhythmia and hypokalemia. Appropriate treatment of primary aldosteronism may avoid insertion of an implantable cardioverter defibrillator.

A new approach to automated assessment of fractionation of endocardial electrograms during atrial fibrillation

Complex fractionated atrial electrograms (CFAEs) may represent the electrophysiological substrate for atrial fibrillation (AF). Progress in signal processing algorithms to identify sites of CFAEs is crucial for the development of AF ablation strategies. A novel algorithm for automated description of fractionation of atrial electrograms (A-EGMs) based on the wavelet transform has been proposed. The algorithm was developed and validated using a representative set of 1.5 s A-EGM (n = 113) ranked by three experts into four categories: 1-organized atrial activity; 2-mild; 3-intermediate; 4-high degree of fractionation. A tight relationship between a fractionation index and expert classification of A-EGMs (Spearman correlation rho = 0.87) was documented with a sensitivity of 82% and specificity of 90% for the identification of highly fractionated A-EGMs. This operator-independent description of A-EGM complexity may be easily incorporated into mapping systems to facilitate CFAE identification and to guide AF substrate ablation.

Optimization of right ventricular lead position in cardiac resynchronisation therapy

BACKGROUND

The benefit of biventricular pacing (BiV) may be substantially affected by optimal lead placement.

AIM

To evaluate the importance of right ventricular (RV) lead positioning on clinical outcome of BiV.

METHODS AND RESULTS

A total of 99 patients with symptomatic heart failure and implantation of BiV system were included. Position of the left-ventricular (LV) lead was selected based on timing of local endocardial signal within the terminal portion of the QRS complex. RV lead was preferably positioned at the midseptum (n=74, RVS group) where the earliest RV endocardial signal was recorded. A subgroup of patients had RV lead placed in the apex (n=25, RVA group). NYHA class, maximum oxygen-uptake (VO(2)max), LV end-diastolic diameter (LVEDD, mm) and ejection fraction were assessed every third month. A trend towards greater improvement in NYHA class and significant increase in VO(2)max was present in the RVS group. Moreover, a significant decrease in LVEDD (DeltaLVEDD) was observed in the RVS group only (-3.4+/-6.5 mm versus +1.7+/-6.4 mm in RVA group at 12 months, p=0.004). No significant correlation between the degree of DeltaLVEDD and QRS narrowing induced by BiV was found. LVEDD reduction was predominantly present in dilated cardiomyopathy.

CONCLUSIONS

Midseptal positioning of the RV lead appears to promote reverse LV remodelling during cardiac resynchronisation therapy.

Surgical ablation of post-infarction ventricular tachycardia guided by mapping in sinus rhythm: long term results☆

OBJECTIVE

Some patients after myocardial infarction have an increased risk of malignant ventricular tachyarrhythmias (VTA) or sudden cardiac death. The aim of the study was to evaluate long-term results of surgical ablation of an arrhythmogenic substrate guided by simplified intraoperative mapping of pathological ventricular electrograms during sinus rhythm.

METHODS

The study population consisted of 77 patients (9 women; mean age 62.4+/-8.5 years) with previous Q-wave myocardial infarction and at least one documented episode of sustained VT/VF more than one month after the last infarction. The left ventricular ejection fraction was 31.3+/-8.8%. All but eight patients had clinical indication for concomitant coronary artery bypass surgery. All underwent preoperative electrophysiologic study. Intraoperative epicardial and endocardial mapping during sinus rhythm was performed using a multielectrode with 16 bipolar electrodes in combination with a multichannel recording system. Myocardial regions revealing fractionated, low amplitude signals lasting > or =130 ms were surgically excised or cryoablated. All surviving patients were restudied within one to two weeks after surgery using identical programmed electrical stimulation protocol.

RESULTS

Five (6.5%) patients died in the perioperative (30-days) period. In the remaining cohort, inducibility of any sustained VTA after surgical procedure was observed in 21 subjects (29.2%). An implantable cardioverter-defibrillator (ICD) was implanted in these patients. Recurrence of sustained VTA was documented during follow-up period in two patients who were noninducible after the surgery (at the month 10 and 22, respectively), and both received ICD as well. No patient died of sudden cardiac death. In 14 ICD patients, no significant VTA was documented during the mean follow-up of 37.3+/-23.2 months. Altogether, 61 from the 72 patients surviving the surgery (84.7%) remained free of spontaneous recurrences of VTA during the follow-up.

CONCLUSIONS

Surgical ablation of an arrhythmogenic substrate guided by simplified intraoperative mapping in normothermic heart during sinus rhythm appears to be both safe and efficacious procedure that prevents recurrences of VTA in a substantial proportion of patients.

Technical Aspects of Implantation of LV Lead for Cardiac Resynchronization Therapy in Chronic Heart Failure

The goal of this study was to analyze total procedural and fluoroscopic time during initial experience with implantation of LV lead in a single center, and to assess the performance of electrophysiologically-guided approach for cannulation of the coronary sinus (CS) in a subsequent period. Over an initial period of 29 months, a total of 46 attempts to implant biventricular pacing system were revised. During the first phase, only one type of LV electrode was available for three implanters (11 attempts). The second phase covered their early experience with other stylet-controlled LV leads (10 attempts). Additional LV leads including the over-the-wire design were available in the third phase and 25 attempts were done by he most experienced implanter. In a period of advanced experience, 92 implant procedures performed by four implanters using an electrophysiologically-guided approach to CS cannulation were revised. In the first period, success rates for different phases reached 70%, 90%, and 96%, respectively. Significant decrease in both procedural and fluoroscopic times was achieved with increased experience (Phase I: 247.1 +/- 104.5 minutes and 31.2 +/- 34.3 minutes, Phase II: 219.4 +/- 85.6 minutes, and 22.9 +/- 19.1 minutes, Phase III: 116.4 +/- 89.9 minutes and 6.6 +/- 4.4 minutes, respectively, P < 0.05). Advanced experience with electrophysiologically-guided approach to CS cannulation allowed achievement of this target within a reasonable amount of time (15.4 +/- 16.3 minutes) and with minimum fluoroscopic time (2.1 +/- 2.9 minutes). In conclusion, both individual learning curve and technical advances significantly influence success rate, procedural, and fluoroscopic times for biventricular system implantation. Electrophysiologically-guided approach makes cannulation of the CS a highly reproducible procedure that requires minimum fluoroscopic time.

Coincidence of idiopathic ventricular outflow tract tachycardia and atrioventricular nodal reentrant tachycardia

BACKGROUND

Tachycardia-induced tachycardia appears to be a relatively rare condition. In such cases an important question arises whether catheter ablation of one arrhythmia may prevent the occurrence of another. This paper reviews single-centre experience with coincident idiopathic outflow tract ventricular tachycardia (VT) and atrioventricular (AV) nodal reentry tachycardia (AVNRT), and strategy of treatment.

METHODS AND RESULTS

Seven of 46 patients (15%) with clinically documented idiopathic outflow tract VT were found to have reproducibly inducible AVNRT at the time of an electrophysiological study. There were two men and five women (mean age 35+/-9 years, range 20-44) without structural heart disease. During the study, AVNRT spontaneously triggered VT in three cases. Radiofrequency catheter ablation of the slow pathway did not suppress subsequent inducibility of VT in any of them. Successful catheter ablation of VT did not prevent clinical recurrence of AVNRT in one patient, and led to transition of VT into typical AVNRT in another.

CONCLUSION

Coincidence of idiopathic outflow tract VT and AVNRT was found in 15% of cases of clinically documented idiopathic VT. Catheter ablation of one arrhythmia substrate did not prevent inducibility or clinical recurrence of the other. These data support the strategy of performing catheter ablation of both arrhythmia substrates during one session.

Clinical application of electroanatomical mapping in the characterization of "incisional" atrial tachycardias

Scar tissue after surgical procedures for congenital heart disease may create a complex arrhythmogenic substrate and expose patients to the risk of "incisional" tachycardia. We report the usefulness of electroanatomical mapping in the characterization of reentrant circuits and identification of sites of successful radiofrequency (RF) ablation.

METHODS

Electroanatomical mapping was used to draw activation maps of the right atrium in 6 men and 4 women (mean age 45 +/- 13.7 years) with 21 atrial tachycardias after corrections of atrial septal defects (n = 6) or tetralogy of Fallot (n = 4). The critical isthmus of reentrant circuits was ablated by RF energy.

RESULTS

Macroreentrant circuits were localized on the posterolateral wall of the right atrium in all cases. Scar tissue in that region often contained several pathways that allowed induction of different tachycardias. Interruption of all slow conducting pathways successfully abolished all inducible tachycardias. The cavotricuspid isthmus participated in a figure-of-eight reentrant circuit or in a typical flutter circuit in 6 patients. RF ablation was successful in all but one patient, without significant complications.

CONCLUSION

Electrocanatomical mapping allows the precise description of macroreentrant circuits and the identification of all slow conducting pathways. It is a powerful tool for the planning of ablation lines, navigation of ablation catheter, and verification of conduction block.

Catheter ablation of ventricular tachycardia following myocardial infarction using three-dimensional electroanatomical mapping

One challenge encountered during catheter ablation of postinfarction ventricular tachycardia (VT) is the inducibility of multiple VT morphologies associated with variable hemodynamic instability. The clinical usefulness and safety of a three-dimensional electroanatomical mapping in guiding radiofrequency (RF) catheter ablation of VT, used in parallel with a multichannel recording system, was studied in 28 men (mean age = 63.8 +/- 10.6 years, mean left ventricular ejection fraction = 28% +/- 9%). Three-dimensional voltage maps of the left ventricle were obtained in sinus rhythm with annotation of areas of fractionated or late potentials, zones of slow conduction and/or dense scar with no pacing capture at 10 mA. RF lesions were created either in sinus rhythm or during hemodynamically stable VT within reconstructed critical zones of the circuit. A total of 82 VTs were induced (mean = 2.9 +/- 1.0/patient). Hemodynamically unstable clinical VTs were induced in 5 patients, and clinical or nonclinical unstable VT in 14. Clinical VT was rendered noninducible in 24/28 (85.7%) patients, and monomorphic VT was eliminated in 16/28 (57.1%) patients. The mean procedural time was 258 +/- 82 minutes, and fluoroscopic exposure 13.5 +/- 8.8 minutes. During a mean follow-up period of 10.6 +/- 6.4 months, catheter ablation was repeated in 6 patients for VT recurrences. No significant complications occurred except for a transient cerebral ischemic attack in one patient. In conclusion, electroanatomical mapping assisted the successful and safe catheter ablation of both mappable and nonmappable VTs in a significant proportion of patients after myocardial infarction.

Radiofrequency catheter ablation of postinfarction ventricular tachycardia from the proximal coronary sinus

Optimum strategy for radiofrequency (RF) catheter ablation of ventricular tachycardia (VT) after inferior wall myocardial infarction (MI) that originates from the posteroseptal process of the left ventricle is not known. We describe a case report of a 57-year-old man who developed recurrent post-MI VT with ECG morphology consistent with this type of VT (i.e., left bundle branch block pattern with predominant R waves from V2 to V6 and left-axis deviation). Endocardial mapping and entrainment during VT demonstrated a critical isthmus of the reentrant circuit in the proximal coronary sinus. RF application terminated VT and rendered it noninducible.

Does angiotensin-converting enzyme polymorphism influence the clinical manifestation and progression of heart failure in patients with dilated cardiomyopathy?

To evaluate the role of angiotensin-converting enzyme (ACE) polymorphism on the development of end-stage dilated cardiomyopathy, the ACE gene polymorphism of 90 patients after heart transplantation because of this disease was compared with the population sample. No difference in gene frequencies was found, but when compared with the population sample there were fewer ID heterozygotes detected; no significant influence of ACE polymorphism on the course of the disease before transplantation was found.

[Pseudoaneurysm of the heart. Report on 4 patients]

A cardiac pseudoaneurysm (PA) is a rare complication of myocardial infarction. It may occur isolated, after cardiosurgery or after an accident. Echocardiography is of fundamental importance in its diagnosis. Coronarography provides important data on the state of the coronary arteries which is essential for planning further, in particular surgical treatment of the condition. The authors describe from four patients with PA.

Control of microorganisms in the rhizosphere of wheat by inoculation of seeds with Pseudomonas putida and by foliar application of urea

After inoculation of wheat seeds with various bacterial strains germination of plants was usually inhibited at first but growth was stimulated later. After inoculation with Pseudomonas putida K 11 producing physiologically active compounds the total number of bacteria increased together with the bacteria: fungi ratio in the rhizosphere. These characteristic were further increased after foliar application of urea due to increased root exudation. Dry mass of upper wheat parts was about 14--80% higher in green-house experiments, in which the plants were treated in the two above ways. More reliable results were usually obtained by bacterization of P. putida and foliar application of urea as compared with the situation when the seeds were inoculated without the foliar application or, on the contrary, after foliar application without inoculation of the seeds. Only when urea was applied early and ain a soil contaminated with the fungus Gaeumannomyces graminis var. tritici (causing "take-all" of the wheat) no favourable results could be detected. In these cases the foliar application without inoculation of the seeds was more successful. Symptoms of the disease of wheat roots caused by G. graminis were less frequently observed after the inoculation of the seeds with the strain P. putida K 11 and after the foliar application of urea.

Rhizosphere microflora and colonization of wheat roots by Gaeumannomyces graminis var. tritici after foliar application of urea and benomyl

The effect of foliar application of 2% urea and 0.6% benomyl on changes in colonization of the rhizosphere by microorganisms and of roots by the fungus Gaeumannomyces graminis (Sacc.) Arx et Olivier var. tritici Walker was followed in vegetation glass-house experiments. Treatment with a urea solution resulted in increased counts of bacteria (82%), Pseudomonas fluorescens (46%), Agrobacterium sp. (31%) and antagonistic bacteria with respect to the used fungus isolate and in a decreased occurrence of micromycetes (63%). Treatment of wheat with a benomyl solution resulted in an increased count of bacteria (43%) and a decreased occurrence of P. fluorescens (16%), Agrobacterium sp. (50%) and fungi (67%). After treatment with both compounds the infection of roots by G. graminis considerably decreased as compared with untreated plants. The results are discussed from the point of view of the effect of application of the studied compounds to upper parts of wheat on the microflora colonizing its roots.

Volatile and gaseous metabolites released by germinating seeds of lentil and maize cultivars with different susceptibilities to fusariosis and smut

The effect of volatile and gaseous metabolites released by germinating seeds of lentil cultivars more and less susceptible to fusariosis on the germination of spores of Mucor racemosus, Trichoderma viride, Verticillium dahliae and Botrytis cinerea was found to depend rather on the fungal genus than on the lentil cultivar. However, spores of Fusarium oxysporum reacted more sensitively during germination to the presence of exudates of both cultivars, when the more susceptible lentil displayed a stimulation, the less susceptible one an inhibition of spore germination. The greatest difference in the effect of exudates was observed in the more and less susceptible maize cultivars with respect to the germination of chlamydospores of Ustilago maydis, especially during the first hours of seed germination. Analysis of the exudates of germinating seeds showed the release of a greater amount of ethanol and methanol with acetaldehyde by the more susceptible cultivars of lentil and particularly maize.

Fluorescent pseudomonads in the rhizosphere of plants and their relation to root exudates

Fluorescent pseudomonads were present in chernozem soil not influenced by plant roots (10(3)-10(4) per g dry soil) in the rhizosphere soil of various plants (10(4)-10(5) per g soil) and on roots (10(3) to 10(7) per g fresh roots), depending on the species and age of the plant. Relative species representation of fluorescent pseudomonads changed on the roots and in the plant rhizosphere as compared with free soil. Pseudomonas fluorescens, representing 60-93% of the population of fluorescent pseudomonads predominated on the roots of all plants investigated. Somewhat different results were obtained in rhizosphere soil. Relatively higher numbers of P. fluorescens were detected in the rhizosphere soil of cucumber and maize, numbers in the rhizosphere soil of wheat were practically the same as in free soil and higher numbers of P. putida were found in the rhizosphere soil of barley. Almost all components contained in the root exudates of the plants studied, including beta-pyrazolylalanine from the root exudates of cucumbers were utilized as carbon and energy sources. Root exudates of wheat and maize were utilized by the strain P. putida K2 with an efficiency of 73-91%, depending on species and age of the plant.

Microorganisms in the rhizosphere of wheat colonized by the fungus Gaeumannomyces graminis var. tritici

The population of microorganisms in wheat rhizosphere changed in the presence of the fungus Gaeumannomyces graminis var. tritici causing the take-all of wheat. In the majority of cases when the soil was artificially contaminated by the fungus, both the number of bacteria in the rhizosphere and the bacteria/fungi ratio temporarily increased. At the beginning bacteria growing in the presence of NH4+ predominated, later bacteria utilizing organic N-substances prevailed. Pseudomonas fluorescens and the related species colonized the rhizosphere and the soil to a greater extent in the presence of G. graminis. The wheat rhizosphere with G. graminis was found to contain a higher level of the slime-producing bacterium Agrobacterium spp.; this microorganism occurred on hyphal surfaces (in hyphosphere) of both G. graminis growing in soil and Mucor spp. Changes in microbial populations in the wheat rhizosphere during the first stage of colonization by G. graminis can be partly explained by a simultaneous rhizosphere colonization by microorganisms which accompany this fungus in soil. In the period of increase in the number of bacteria in rhizosphere a temporary stimulation of wheat growth was observed.

Effect of bacterial polysaccharides on the growth of Gaeumannomyces graminis var. tritici and wheat roots

Agrobacterium sp. and related species which in the soil and in the rhizosphere of wheat accompany the fungus Gaemannomyces graminis var. tritici and cause take-all of the wheat roots produced polysaccharides in pure cultures (glucans, mannoglucans and galactomannoglucans). These polysaccharides were utilized better by the mycelium of G. graminis than glucose and polysaccharides of plant origin that occurred on the surface of wheat roots (the so-called mucigel). At lower concentrations these bacterial polysaccharides stimulated growth of wheat roots, higher concentrations (more than 0.1%) were inhibitory. Bacteria inoculated on the surface of wheat first inhibited and then stimulated the development of the plants and their growth. Changes in the growth rate of wheat, the rhizosphere of which was colonized by bacteria simultaneously with the fungus G. graminis and also some changes in the course of the disease of wheat roots caused by the fungus can be explained by the inhibitory or stimulatory effect of polysaccharides of accompanying bacteria.

The effect of volatile and gaseous metabolites of swelling seeds on germination of fungal spores

Effects of volatile and gaseous metabolites of swelling seeds of pea, bean, wheat, corn cucumber, tomato, lentil, carrot, red papper and lettuce on germination of spores of five genera of fungi were found to depend rather on the fungal than on the plant genus. Germination of spores of Botrytis cinerea, Mucor racemosus and Trichoderma viride was most severely inhibited. Spores of Verticillium dahliae were less sensitive and germination of spores of Fusarium oxysporum was inhibited only in two cases. On the other hand, exudates of pea and bean stimulated germination of spores of Fusarium oxysporum. Also spores of Trichoderma viride germinated better in an atmosphere enriched with exuded metabolites of swelling lettuce seeds. When carbon dioxide produced by the swelling seeds was absorbed in potassium hydroxide, spores of Trichoderma viride and Verticillium dahliae did not germinate at all, the inhibitory effects of volatile and gaseous exudates on germination of spores of Mucor racemosus were accentuated, and also the percentage of germinated spores of Fusarium oxysporum decreased. Germination of spores of Botrytis cinerea was not influenced. Absorption of volatile and gaseous metabolites in a solution of potassium permanganate decreased in most cases their inhibitory effects, particularly in Botrytis cinerea.