Interatrial Conduction Measured During Biventricular Pacemaker Implantation Accurately Predicts Optimal Paced Atrioventricular Intervals

BACKGROUND

Optimizing atrioventricular (AV) delay during biventricular (BiV) pacemaker implantation can require substantial resources. Hence, a simpler method is desirable. We hypothesized that interatrial conduction time (IACT), measured at the time of BiV device implant, could be a surrogate value for the optimal AV delay.

OBJECTIVE

This study determined the relationship between paced IACT and the optimal paced AV delay (PAV), as determined by echocardiography.

METHODS

Consecutive subjects (N = 25; age = 66 +/- 10 years; M/F: 17/8) undergoing BiV pacemaker implantation and in sinus rhythm were included. Cannulation of the coronary sinus (CS) was at the operator's discretion. A quadripolar electrophysiology catheter was inserted via the guiding sheath into the inferiolateral CS to measure left atrial depolarization. The IACT was calculated as the interval between right atrial stimulation artifact and earliest deflection on the coronary sinus catheter electrogram. Subsequently, during atrial pacing the PAV was determined using transmitral pulsed wave Doppler echocardiography (iterative method). The relationship between paced IACT and PAV was then determined.

RESULTS

The mean +/- SD paced IACT and PAV were 126 +/- 25 msec and 157 +/- 23 msec, respectively. There was a strong positive correlation between the paced IACT and PAV (r = 0.73, P < 0.001). The equation describing the relationship was PAV = 0.68 * (IACT + 104) msec.

CONCLUSIONS

The paced IACT has a strong correlation with the echo derived optimal PAV. This method may be used to program PAV intervals without need for echocardiography in patients undergoing BiV pacemaker implantation.

On the accuracy of CartoMerge for guiding posterior left atrial ablation in man

BACKGROUND

Recent reports suggest that the CartoMerge system is useful for guiding human posterior left atrial (PLA) endocardial ablation.

OBJECTIVE

To assess the accuracy of the CartoMerge system during PLA ablation.

METHODS

Sixteen patients undergoing PLA catheter ablation were studied. In each patient, registration of preoperative computed tomographic (CT) and intraoperative electroanatomic left atrial images was performed to create CartoMerge images. Encircling of right and left pulmonary venous vestibules with ablation points was then performed guided solely by intracardiac echocardiography, with point locations saved on a CartoMerge image to which the operator was blinded. The accuracy of the CartoMerge image was then assessed by measuring the distance from the location of each ablation point on the image to its actual anatomic location. In five patients, accuracy of registration of each of three left atrial CT images (just prior to mitral valve opening, at end-diastasis, at end-atrial contraction) with the electroanatomic image was compared. In two patients, accuracy of registration using left atrial image data alone was compared with that which used both left atrial and thoracic aorta image data.

RESULTS

In each patient, inaccuracy of the CartoMerge image was apparent, the magnitude of which was similar for right- and left-vestibule ablation points. Accuracy was significantly improved when the end-atrial contraction CT image was used for registration. The inclusion of thoracic aorta image data did not improve accuracy.

CONCLUSIONS

The CartoMerge system is inaccurate. Inaccuracy may be reduced by using CT and electroanatomic images obtained at the same point in the atrial mechanical cycle.

Efficacy of Adjuvant Anterior Left Atrial Ablation During Intracardiac Echocardiography-Guided Pulmonary Vein Antrum Isolation for Atrial Fibrillation

BACKGROUND

Recent data have shown that the septum and anterior left atrial (LA) wall may contain "rotor" sites required for AF maintenance. However, whether adding ablation of such sites to standard ICE-guided PVAI improves outcome is not well known.

OBJECTIVE

To determine if adjuvant anterior LA ablation during PVAI improves the cure rate of paroxysmal and permanent AF.

METHODS

One hundred AF patients (60 paroxysmal, 40 persistent/permanent) undergoing first-time PVAI were enrolled over three months to receive adjuvant anterior LA ablation (Group I). These patients were compared with 100 randomly selected, matched first-time PVAI controls from the preceding three months who did not receive adjuvant ablation (Group II). All 200 patients underwent ICE-guided PVAI during which all four PV antra and SVC were isolated. In group I, a decapolar lasso catheter was used to map the septum and anterior LA wall during AF (induced or spontaneous) for continuous high-frequency, fractionated electrograms (CFAE). Sites where CFAE were identified were ablated until the local EGM was eliminated. A complete anterior line of block was not a requisite endpoint. Patients were followed up for 12 months. Recurrence was assessed post-PVAI by symptoms, clinic visits, and Holter at 3, 6, and 12 months. Patients also wore rhythm transmitters for the first 3 months. Recurrence was any AF/AFL >1 min occurring >2 months post-PVAI.

RESULTS

Patients (age 56 +/- 11 years, 37% female, EF 53%+/- 11%) did not differ in baseline characteristics between group I and II by design. Group I patients had longer procedure time (188 +/- 45 min vs 162 +/- 37 min) and RF duration (57 +/- 12 min vs 44 +/- 20 min) than group II (P < 0.05 for both). Overall recurrence occurred in 15/100 (15%) in group I and 20/100 (20%) in group II (P = 0.054). Success rates did not differ for paroxysmal patients between group I and II (87% vs 85%, respectively). However, for persistent/permanent patients, group I had a higher success rate compared with group II (82% vs 72%, P = 0.047).

CONCLUSIONS

Adjuvant anterior LA ablation does not appear to impact procedural outcome in patients with paroxysmal AF but may offer benefit to patients with persistent/permanent AF.

Right atrial angiography facilitates transseptal puncture for complex ablation in patients with unusual anatomy

OBJECTIVE

The number of transseptal punctures performed worldwide has increased exponentially with the development of ablation therapies for atrial arrhythmias. Safe access into the left atrium in these procedures is often complicated by abnormal anatomy. We assessed the potential of right atrial angiography to facilitate transseptal puncture for atrial ablation.

METHODS AND RESULTS

We examined all transseptal punctures performed for complex left atrial ablation in our centre over a 29-month period. In cases where conventional transseptal techniques failed, we performed orthogonal right atrial angiography to define cardiac anatomy and orientation. During the study period, 255 transseptal procedures were performed. Of these, 16 cases were complicated by distorted atrial anatomy, extreme cardiac rotation or unexpected location of the atria in relation to the diaphragm, preventing left atrial access using conventional fluoroscopy. The application of right atrial angiography facilitated successful transseptal puncture in all patients when use of conventional mapping catheters and fluoroscopy proved unhelpful. There were no complications relating to right atrial angiography.

CONCLUSION

These cases highlight a number of difficulties encountered when performing transseptal punctures. Previously reported adjunctive techniques require specialised equipment, general anaesthesia or multiple catheters that may be unavailable or impede the procedure. Right atrial angiography is a simple and safe adjunct to conventional techniques to facilitate complex transseptal procedures.

Effects of Cilazapril on atrial electrical, structural and functional remodeling in atrial fibrillation dogs

BACKGROUND AND PURPOSE

The effects of angiotensin-converting enzyme inhibitor on long-term atrial electrophysiologic and structural remodeling are still unclear. The purpose of this study is to investigate the effects of Cilazapril on atrial electrical, structural, and functional remodeling in atrial fibrillation (AF) dogs induced by chronic rapid atrial pacing.

METHODS

Twenty dogs were randomly divided into sham-operated group (n = 6), control group (n = 7), and Cilazapril group (n = 7). One thin silicon plaque containing 4 pairs of electrodes was sutured to each atrium. A pacemaker was implanted in a subcutaneous pocket and attached to a screw-in epicardial lead in the right atrial appendage. The dogs in control group and Cilazapril group were paced at 400 beats per minute for 6 weeks. The dogs in Cilazapril group received Cilazapril (0.5 mg x kg(-1) x d(-1)) 1 week before rapid atrial pacing until pacing stop. Before and after 6-week rapid atrial pacing, atrial effective refractory period (AERP) at 8 sites, AERP dispersion, intraatrium conduction time, inducibility, and duration of AF were measured. Transthoracic and transesophageal echocardiographic examinations included left atrium (LA) maximal volume, LA minimal volume, LA ejection fraction, left atrial appendage (LAA) maximal volume, LAA minimal volume, LAA ejection fraction, LAA maximal forward flow velocity, and LAA minimal backward flow velocity were performed. Atrial collagen volume fraction was analyzed by Masson staining.

RESULTS

After 6-week rapid atrial pacing, although there was no significant difference in AERP shortening and AERP rate adaptation reduction between the control group and the Cilazapril group, the inducibility and duration of AF were found to be dramatically lower in the Cilazapril group than those in the control group (AF inducibility, 65.7% vs 95.7%, P < .05; AF duration, 531.5 +/- 301.2 vs 1432.2 +/- 526.5 s, P < .01). The post-tachycardia intraatrium conduction times after 6 weeks with Cilazapril were significantly shorter than those in the control group. Cliazapril could partially prevent AERP dispersion increase induced by chronic rapid atrial pacing. Compared with the control group, the LA and LAA volumes were significantly smaller; LA ejection fraction, LAA ejection fraction, LAA maximal forward flow velocity, and LAA minimal backward flow velocity were dramatically higher in the Cilazapril group. The Cilazapril group had a significantly lower percentage of interstitial fibrosis than the control group.

CONCLUSIONS

Cilazapril can suppress structural and functional remodeling and prevent the induction and promotion of AF in chronic rapid atrial pacing dogs.

[Current approaches to echocardiographic assessment of systolic function of the heart]

Among modern methods of visualization of the heart echocardiography is most often used for assessment of systolic function of the heart. The reasons for this are noninvasive character of investigation, absence of ionizing radiation, quickness of carrying out, availability and wide dissemination of echocardiography. Parameter of systolic function most wanted in the clinic is ejection fraction. Advantages and drawbacks of various techniques of calculation of ejection fraction obtained at echocardiography are analyzed in the paper. Comparison with other contemporary methods of imaging of the heart and evaluation of cardiac systolic function is conducted as well. The authors underline importance of complex assessment of systolic function of the heart proceeding from basic disease with consideration of anatomical and functional specific features of the heart as well as character of intracardiac hemodynamics. Supplementary and alternative variants of analysis of systolic function of the heart, based on visual assessment of contractility and on the use of Doppler curves are also discussed.

[The influence of intracardiac asynchronism on the clinical course of chronic cardiac insufficiency]

Intracardiac asynchronism presents systolic and/or diastolic dyscoordination in different myocardial areas within one and/or between different cardiac chambers. QRS complex widening is the marker of electric asynchronism. In 1/3 of patients with chronic cardiac insufficiency (CCI), the width of QRS complex is more than 120 msec. sixty-five CCI patients (56 men aged 63.7 +/- 7.3 years and 9 women aged 66.8 +/- 8.2 years) were divided into two groups: the group with a wide QRS (more than 120 msec) and the group with a narrow QRS (less than 120 msec), 30 and 35 patients, respectively. In the group with a wide QRS, 96.6% of patients suffered from clinically significant CCI (functional class III to IV); in the other group it was observed in 65.7% of patients. The patients were observed during three years. CCI dynamics was evaluated, quality of life was assessed using the Russian version of SF questionnaire, and three-year survival rate was assessed by Kaplan-Meyer method. The presence of electric asynchronism in a form of a wide QRS complex promotes CCI progression, accompanied by CCI functional class deterioration as well as clinical worsening and decreased physical exercise tolerance according to 6-min walking test. The frequency of seeking medical aid was significantly higher among patients with a wide QRS complex.

Three-dimensional activation sequence imaging in a rabbit model

This paper evaluates a biophysical-model based three-dimensional (3-D) activation sequence imaging approach in a rabbit model. In this approach, cardiac electrical sources within the myocardial volume are represented by distributed equivalent current densities; a realistic heart-torso volume conductor model is built from the CT scans of the rabbit's torso; spatial-temporal regularization is applied when solving the inverse problem of current density estimation; and the activation time at every myocardial location is determined as the time point when the estimated local current density reaches its maximum amplitude. Computer simulations have been conducted to image the activation sequence initiated by pacing 11 sites throughout the ventricular myocardium. Under 20muV Gaussian white noise, the average correlation coefficient (CC) between the imaged and the simulated activation sequences is 0.92, the average relative error (RE) is 0.19, and the average localization error (LE) is 4.99mm averaged over 11 pacing sites. Even under 60muV Gaussian white noise, reasonable results can still be achieved by the present approach with CC = 0.89, RE = 0.22, and LE = 6.85mm. The simulation results demonstrate that the present 3-D imaging approach has reasonable accuracy and robustness against recording noises.

Prevalence of normal coronary angiography in the acute phase of suspected ST-elevation myocardial infarction: experience from the PRAGUE studies

BACKGROUND

Acute ST-elevation myocardial infarction in patients with normal coronary arteries has previously been described, but coronary angiography in these patients was performed after the acute phase of the infarction. It is possible that these patients did not have normal angiograms during the acute phase (transient coronary thrombosis or spasm were usually suspected to be the cause). Information on the prevalence of truly normal coronary angiograms during the acute phase of a suspected ST-elevation myocardial infarction is lacking.

PATIENTS AND METHODS

The Primary Angioplasty in patients transferred from General community hospitals to specialized PTCA Units with or without Emergency thrombolysis-1 (PRAGUE-1) and PRAGUE-2 studies enrolled 1150 patients with ST-elevation acute myocardial infarction, in whom 625 coronary angiograms were performed within 2 h of the initial electrocardiogram. A simultaneous registry included an additional 379 coronary angiograms performed during the ST-elevation phase of a suspected myocardial infarction. Thus, a total of 1004 angiograms were retrospectively analyzed. A normal coronary angiogram was defined as one with the absence of any visible angiographic signs of atherosclerosis, thrombosis or spontaneous spasm.

RESULTS

Normal coronary angiograms were obtained for 26 patients (2.6%). Among these, the diagnosis at discharge was a small myocardial infarction in seven patients (0.7%), acute (peri)myocarditis in five patients, dilated cardiomyopathy in four patients, hypertension with left ventricular hypertrophy in three patients, pulmonary embolism in two patients and misinterpretation of the electrocardiogram (ie, no cardiac disease) in five patients. Seven patients with small infarctions underwent angiography within 30 min to 90 min of complete relief of the signs of acute ischemia, and thus, angiograms during pain were not taken. None of the 898 patients catheterized during ongoing symptoms of ischemia had a normal coronary angiogram. Spontaneous coronary spasm as the only cause (without underlying coronary atherosclerosis) for the evolving infarction was not seen among these 898 patients. Thus, the causes of the seven small infarcts in patients with normal angiograms remain uncertain.

CONCLUSIONS

The observed prevalence of normal coronary angiography in patients presenting with acute chest pain and ST elevations was 2.6%. Most of these cases were misdiagnoses, not infarctions. A normal angiogram during a biochemically confirmed infarction is extremely rare (0.7%) and was not seen during the ongoing symptoms of ischemia.

Clinical features of transient left ventricular apical ballooning

This report describes the clinical characteristics of 8 consecutive patients with transient left ventricular apical ballooning identified among 389 patients (2%) admitted to a tertiary referral hospital with suspected acute coronary syndromes over a 1-year period. Among these patients, 2 cases appeared to be caused by acute myocarditis and 1 case by head trauma with intracranial bleeding. In the remaining 5 cases, no apparent cause was found. All patients but 1 were postmenopausal women (mean age 60 +/- 13.5 years). Preceding strong emotional or physical stress was present in 6 patients. The presenting symptom in 7 patients was chest pain. Four patients had significant ST-segment elevation, and the remaining 4 had T-wave inversions on their admission electrocardiograms. Mean peak troponin I was moderately elevated (3.7 +/- 4.5 ng/dl). The mean echocardiographic left ventricular ejection fraction was 40 +/- 10% on admission and increased significantly to 63 +/- 4% at 1-month follow-up (p <0.0001). All patients but 1 had abnormal corrected Thrombolysis In Myocardial Infarction frame counts (>27 frames) in >or=1 major epicardial coronary artery. All patients were alive and without major adverse cardiac events at 6-month follow-up. In conclusion, transient left ventricular apical ballooning should be considered in the differential diagnosis of patients presenting with suspected acute coronary syndromes, because it may account for approximately 2% of hospital admissions.

Gated blood pool tomoscintigraphy with 4-dimensional optical flow motion analysis quantifies left ventricular mechanical activation and synchronization

BACKGROUND

Gated blood pool tomoscintigraphy has the unique capacity to accurately assess myocardial motion in paced patients. Our goal was to develop a precise radionuclide angiography analysis of cardiac dynamics to evaluate ventricular synchronization in patients undergoing biventricular pacing.

METHODS AND RESULTS

On the basis of a 4-dimensional deformable motion estimation algorithm, we developed a protocol allowing estimation of motion fields after gated blood pool tomoscintigraphy. We measured the mechanical activation times for 17 left ventricular (LV) segments and determined the main types of contraction pattern in 10 normal subjects, 17 patients with dilated cardiomyopathy, and 12 resynchronized patients. We analyzed intra-LV dyssynchrony: apex to base, septum to lateral wall, and anterior wall to inferior wall. Three-dimensional measurements of intra-LV activation time (r > .80, P < .001) and LV ejection fraction (r > 0.90, P < .0001) are linearly correlated to 2-dimensional values. LV contraction follows the electrical activation pattern. In normal subjects the anteroseptal and anterior segments are first activated, followed by the apex and inferolateral segments. In resynchronized patients contraction begins with the lateral and apicoseptal segments in correspondence to the LV and right ventricular lead implantation.

CONCLUSIONS

By measuring mechanical activation times, this technique allows for the analysis of the regional synchronous contraction. This may help to assess the variation of the activation pattern according to the cardiomyopathy type and the role of septal resynchronization in ventricular functional recovery.

Role of myocardial bridging in the apical localization of stress cardiomyopathy

BACKGROUND

The apical ballooning syndrome is precipitated by emotional or physical stress but the underlying mechanism remains poorly understood. The contribution of myocardial bridging on the aetiology and the onset of the syndrome is not known.

METHODS

We observed 8 patients with chest pain, T-wave inversion in several leads of the ECG, transient left ventricular apical ballooning and no significant angiographic stenosis.

RESULTS

There were 7 women and I man. The median age was 67.5 years. Seven patients had an intense emotional or physical stress (87.5%). All patients presented with chest pain and aT-wave inversion in the precordial leads. The median elevation of creatine-kinase was 171 IU. In all patients, echocardiography showed an alteration of the left ventricular function with a very extensive apical akinesia. Left ventricular hypertrophy was observed in 7 patients. A myocardial bridging in the mid segment of the left anterior descending coronary artery was observed in 5 patients (62.5%). Recovery was complete in all patients. During follow-up, no patient showed recurrence.

CONCLUSIONS

Our data suggest that myocardial bridging possibly enhanced by catecholamines during stress may contribute, in association with left ventricular hypertrophy, to the preferential apical localization of the apical ballooning syndrome. Further investigations are necessary to confirm

Cardiac resynchronization therapy: Role of patient selection

Cardiac resynchronization therapy (CRT) is a well-accepted and effective therapy for treating patients with a wide QRS complex, significant left ventricular systolic dysfunction, and symptoms of advanced heart failure. However, approximately 25% to 30% of patients fail to respond to this therapy. Most large studies have used electrical dyssynchrony (wide QRS) as a main entrance criterion. Emerging data suggest that mechanical dyssynchrony may be a more important factor in selecting appropriate candidates for CRT. New echocardiographic (ECHO) imaging modalities such as tissue Doppler imaging, three-dimensional ECHO, and speckle tracking ECHO are able to quantify left ventricular mechanical dyssynchrony. These techniques are currently being used to assist in the selection of patients for CRT. Recently published and ongoing studies are addressing the use of CRT in patients who do not meet the standard criteria, such as patients with atrial fibrillation, mild to moderate heart failure, narrow QRS complex, and acute myocardial infarction.

Cardioversion under the guidance of transesophageal echochardiograhy in persistent atrial fibrillation: results with low molecular weight heparin

BACKGROUND

Transesophageal echocardiography (TEE) guided cardioversion to restoration of sinus rhythm is a therapeutic option in patients with atrial fibrillation (AF). Anticoagulation at the time of and after cardioversion is necessary to prevent formation of new thrombus during atrial stunning period. We aimed to evaluate the efficacy and safety to TEE guided cardioversion with low molecular weight heparin (LMWH) in patients with atrial fibrillation.

METHODS

We followed up 208 patients with persistent AF (mean age: 65.5+/-10.2 years) who were attempted TEE guided cardioversion. LMWH were used as an anticoagulant and warfarin therapy was continued.

RESULTS

Cardioversion were performed in 183 patients. Sinus rhythm restored in 144 patients (78.7%). Mean follow up duration was 155 days. No cardiac death occurred. In the early follow up period (within 30 day) one thromboembolic event (0.54%) occurred in a patient who was cardioverted. Two patients who had not been cardioverted because of left atrial thrombus presented embolic stroke, one in early and another in late follow up period. All embolic complications occurred in patients who had been taking warfarin and whose INR level was subtherapeutic at the time of stroke. Sinus rhythm was maintained in 64% and total hemorrhagic complications occurred in 4.8% of the patients in long-term follow-up.

CONCLUSION

TEE guided cardioversion with a short-term anticoagulation protocol using low molecular weight heparin is a safe and effective method in restoring and maintaining sinus rhythm and enables us to make earlier cardioversion in atrial fibrillation.

A case-control study on the prevalence of electrocardiographic rhythms and ischemic changes in elderly patients with acute cerebrovascular disease

Electrocardiographic (ECG) abnormalities have been observed in acute cerebrovascular events. This case-control study investigated the prevalence of ECG rhythms and ischemic changes in elderly stroke and medical patients. The ECG rhythms and ischemic changes of 97 elderly patients admitted with acute stroke or transient ischemic attack (TIA) were compared with those of 70 medical controls admitted during the same study period. Patients' median age was 80 years. Atrial fibrillation occurred in 26 stroke/TIA patients (27%) and 17 control patients (24%). Ischemic ECG changes occurred in 54 stroke/TIA patients (56%) and 32 control patients (46%) (odds ratio, 1.52; 95% confidence interval, 0.82-2.83; p=0.18). Seventeen stroke/TIA patients (18%) vs. 19 (27%) control patients had a history of ischemic heart disease. After adjustment for ischemic heart disease, the odds ratio for ischemic ECG changes was 1.80 (95% confidence interval, 0.93-3.45; p=0.079). Atrial fibrillation accounted for a quarter of ECG rhythms in elderly acute stroke/TIA patients and elderly medical patients. The high frequency of ischemic ECG changes found in the stroke/TIA patients was not significantly different from that in the control patients. After adjustment for ischemic heart disease, there emerged a trend of borderline significance to suggest that ischemic ECG changes were more strongly associated with elderly acute stroke/TIA patients than elderly control patients. Larger outcome study will be required to determine the significance of ischemic ECG changes following acute cerebrovascular events in older patients.

Does Proximal Location of Culprit Lesion Confer Worse Prognosis in Patients Undergoing Primary Percutaneous Coronary Intervention for ST Elevation Myocardial Infarction?

ST segment elevation myocardial infarction (STEMI) from proximally located culprit lesion is associated with greater myocardium at jeopardy. In STEMI patients treated with thrombolytics, proximal culprit lesions are known to have worse prognosis. This relation has not been studied in patients undergoing primary percutaneous coronary intervention (PCI). In 3,535 STEMI patients with native coronary artery occlusion pooled from the primary angioplasty in myocardial infarction database, we compared in-hospital and 1-year outcomes between those with proximal (n = 1,606) versus non-proximal (n = 1,929) culprit lesions. Patients with proximal culprits were more likely to die and suffer major adverse cardiovascular events (MACE) during the index hospital stay (3.8% vs 2.2%, P = 0.006; 8.2% vs 5.8%, P = 0.0066, respectively) as well as during 1-year follow-up (6.9% vs 4.5%, P = 0.0013; 22% vs 17%, P = 0.003, respectively) compared to those with non-proximal culprits. After adjustment for baseline differences, proximal culprit was independently predictive of in-hospital death (adjusted odds ratio% 1.58, 95% confidence intervals, CI 1.05-2.40) and MACE (OR 1.41, CI 1.06-1.86), but not 1-year death or MACE. In addition, proximal culprit was independently associated with higher incidence of ventricular arrhythmias and sustained hypotension during the index hospitalization. The univariate impact of proximal culprit lesion on in-hospital death and MACE was comparable to other adverse angiographic characteristics, such as multivessel disease and poor initial thrombolysis in myocardial infarction flow, and greater than that of anterior wall STEMI. In conclusion, proximal location of the culprit lesion is a strong independent predictor of worse in-hospital outcomes in patients with STEMI undergoing primary PCI.

Marshall vein as arrhythmogenic source in patients with atrial fibrillation: correlation between its anatomy and electrophysiological findings

BACKGROUND

Atrial fibrillation (AF) may originate from catecholamine-sensitive vein of Marshall (VOM) or its ligament in addition to pulmonary veins (PVs). The anatomy of VOM and its relation to arrhythmogenic foci in the left atrium are unknown. We studied the anatomy of VOM and its relation to foci in patients with AF.

METHODS

The study population consisted of 100 patients with AF (mean age, 62 years; chronic AF, n = 15). AF sources were determined at baseline and after isoproterenol administration without sedation. VOM was identified by balloon-occluded coronary sinus (CS) angiography. We determined its anatomy in relation to left PVs.

RESULTS

VOM was visualized in 73 patients (73%). Ninety-seven patients had 269 arrhythmogenic foci (PV, n = 77; non-PV, n = 48). Non-PV foci included left atrial posterior wall (24, 9%), left lateral area (12, 4.5%), roof (6, 2.2%), superior vena cava (28, 10.4%), crista terminalis (8, 3.0%), CS (10, 3.7%), and others (10, 3.7%). The incidence of PV foci in the left superior PV (LSPV) was significantly higher in patients with well-developed VOM than in those without (66% vs 42%, P < 0.05). Twenty-eight patients had 30 non-PV foci around the LSPV ostium. We successfully ablated the non-PV foci at the distal end of VOM in 11 patients. The ends of the VOM branches were good markers to search for non-PV foci. Seven of 11 (64%) patients with successful ablation of non-PV foci were free from arrhythmia, whereas only 6 of 17 (35%) were free from arrhythmia in those with residual non-PV foci.

CONCLUSIONS

To determine VOM anatomy is important to identify non-PV foci around the ends of VOM.

Remote magnetic navigation for mapping and ablating right ventricular outflow tract tachycardia

BACKGROUND

Navigation, mapping, and ablation in the right ventricular outflow tract (RVOT) can be difficult. Catheter navigation using external magnetic fields may allow more accurate mapping and ablation.

OBJECTIVES

The purpose of this study was to assess the feasibility of RVOT tachycardia ablation using remote magnetic navigation.

METHODS

Mapping and ablation were performed in eight patients with outflow tract ventricular arrhythmias. Tachycardia mapping was undertaken with a 64-polar basket catheter, followed by remote activation and pace-mapping using a magnetically enabled catheter. The area of interest was localized on the basket catheter in seven patients in whom an RVOT arrhythmia was identified. Remote navigation of the magnetic catheter to this area was followed by pace-mapping. Ablation was performed at the site of perfect pace-mapping, with earliest activation if possible.

RESULTS

Acute success was achieved in all patients (median four applications). Median procedural time was 144 minutes, with 13.4 minutes of patient fluoroscopy time and 3.8 minutes of physician fluoroscopy time. No complications occurred. One recurrence occurred during follow-up (mean 366 days).

CONCLUSION

RVOT tachycardias can be mapped and ablated using remote magnetic navigation, initially guided by a basket catheter. Precise activation and pace-mapping are possible. Remote magnetic navigation permitted low fluoroscopy exposure for the physician. Long-term results are promising.

The Use of Echocardiography for the Evaluation of Dyssynchrony

Tissue Doppler imaging (TDI), is a new imaging tool that allows measurement of dyssynchrony. In several small studies, TDI predicted clinical response and reverse remodeling after cardiac resynchronization therapy (CRT). Moreover, it allowed detection of mechanical dyssynchrony in heart failure patients with narrow QRS. Using TDI, the selection criteria for CRT might be changed to include heart failure patients with narrow QRS. Furthermore, it will help predict responders to this therapy, hence decreasing the percentage of nonresponders and allowing a more cost-effective use of this new technology.

Indices of Electrical and Contractile Remodeling During Atrial Fibrillation in Man

BACKGROUND

Atrial electrical and contractile remodeling have been demonstrated to coincide during atrial fibrillation (AF) in experimental studies. We explored whether electrical and contractile remodeling correlate in man and explored its clinical implications.

METHODS

Forty-nine patients with persistent AF were studied. Electrical remodeling was assessed noninvasively using spectral analysis to estimate the average fibrillatory rate (AFR). Atrial contractility was assessed by transesophageal echocardiography (TEE) measurement of left atrial appendage outflow velocity (LAAOV).

RESULTS

The AFR was 403+/-43 fibrillations per minute (fpm) and the LAAOV was 0.27+/-0.14 m/s. A significant correlation was found between AFR and LAAOV (r=-0.47, P=0.001). In patients with a LAAOV>or=0.25 m/s, the AFR was 387+/-48 fpm compared to 419+/-31 fpm among patients with LAAOV<0.25 m/s (P<0.01).

CONCLUSIONS

This study demonstrates that indices of electrical and contractile remodeling are strongly correlated in persistent AF in man. The interindividual overlap, however, is too large to allow predictions of LAAOV based on fibrillatory frequency alone.

Cardiac resynchronization therapy in congenital heart disease

While cardiac resynchronization therapy (CRT) is of proven benefit in selected patients with severe ischemic or dilated cardiomyopathy, refractory symptoms, and conduction delay, extrapolation to congenital heart disease is not straightforward. This rapidly expanding patient population commonly suffers from heart failure, particularly in the presence of a single or systemic right ventricle. Surgical repair may also contribute to ventricular asynchrony. In this systematic review, the current state of knowledge regarding CRT in congenital heart disease is presented. Issues specific to congenital heart disease including right bundle branch block, right (pulmonary) ventricular dysfunction, systemic right ventricular dysfunction, and single ventricle dysfunction are explored. Evidence-based CRT applications for each of these particular conditions are reviewed. Initial experience with CRT in the acute postoperative setting and longer-term, including our own, is elaborated. Unlike standard indications based on multiple randomized clinical trials, supporting evidence for CRT in congenital heart disease is limited to case reports, case series, and small experimental crossover studies in the acute postoperative setting. The heterogeneous patient population, technical limitations from patient size, vascular access issues, and unique forms of ventricular asynchrony further obscure the selection of potential beneficiaries. Despite these limitations, experience thus far has been favorable. Quality of current data precludes definitive evidence-based recommendations, but optimistic initial results suggest that research endeavors in this field should be pursued. Multicenter prospective collaborative efforts are to be encouraged.

Effect of Tirofiban Therapy on ST Segment Resolution and Clinical Outcomes in Patients with ST Segment Elevated Acute Myocardial Infarction Undergoing Primary Angioplasty

BACKGROUND

In our study, we assessed the effect of glycoprotein (GP) IIb/IIIa receptor inhibition on microvascular flow after acute coronary occlusion using the early sum of ST segment resolution in electrocardiography. Platelets may play a major role in the dissociation of epicardial artery recanalization and tissue level reperfusion, referred to as the 'no-reflow phenomenon'. Therefore, GP IIb/IIIa receptor inhibition might improve myocardial reperfusion, distinct from its effects on epicardial patency.

METHODS AND RESULTS

One hundred and fifteen patients (mean age 57.7 +/- 12.2 years, 96 males, 19 females) with < or = 12-hour acute ST segment elevation myocardial infarction who underwent successful primary percutaneous coronary intervention were retrospectively enrolled into the study. Patients were grouped according to whether they received tirofiban therapy or not. Clinical and electrocardiographic parameters were evaluated. The first sum of ST segment elevation amounts in millimeters was obtained immediately before angioplasty and the second 60 min after restoration of thrombolysis in myocardial infarction III flow. The difference between the two measurements was accepted as resolution of the sum of ST segment elevation and expressed as SigmaSTR. There were no significant differences between the groups regarding age, gender, cardiovascular risk factors, and laboratory parameters, duration from angina onset to the emergency unit, and from door to angioplasty. SigmaSTR was higher in patients who received tirofiban than in those who did not (7.2 +/- 2.8 and 4.2 +/- 2.6 mm, respectively; p < 0.001). There was a significant and positive correlation between GP IIb/IIIa inhibition and SigmaSTR (r = 0.336, p < 0.001), as well as between ejection fraction and SigmaSTR (r = 0.310, p < 0.001). GP IIb/IIIa inhibition was the only independent determinant of SigmaSTR in a multivariate linear regression model which contains 10 variables (p < 0.001). The incidence of in-hospital post-myocardial infarction refractory angina, reinfarction, and heart failure was significantly lower in the tirofiban group (p < 0.05, p < 0.05, and p < 0.05, respectively). Additionally, after 30 days, reinfarction and heart failure were lower in the tirofiban group (p < 0.05 and p < 0.05, respectively).

CONCLUSIONS

It is well known that SigmaSTR determines microvascular perfusion. This study shows that GP IIb/IIIa inhibition with tirofiban is of value in preserving microvascular perfusion after restoring coronary thrombolysis in myocardial infarction III flow.

Prospective validation of stress echocardiography as an identifier of cardiac resynchronization therapy responders

BACKGROUND

Cardiac resynchronization therapy (CRT) provides benefit for congestive heart failure (CHF), but predictors of the clinical response are debated.

OBJECTIVE

The aim of this prospective study was to assess the predictive role of dobutamine stress echocardiography (DSE) in identifying a suitable candidate for CRT.

METHODS

From March 2001 to December 2003, 71 CHF patients were prospectively enrolled on the basis of four criteria: New York Heart Association (NYHA) class III and IV; QRS > or =150 ms with a left bundle branch block pattern, and left ventricular ejection fraction (LVEF) < or =35% under optimal medical treatment. The combined endpoints were hospital readmission for class IV CHF, heart transplant (HT), and CHF-related death.

RESULTS

The 67 patients completing the study presented with the following characteristics: age (70 +/- 10 years; 11 women); etiology (idiopathic in 44, ischemic in 23); NYHA class (40 in class III and 27 in class IV); LVEF 26% (+/-5%); QRS duration (190 +/- 28 ms); 6-minute walk test 330 m (+/-108); peak oxygen uptake 10.7 (+/-3.3 mL/kg/min); mitral insufficiency in 42 (> or =III grade); interventricular (IV) delay (62 +/- 21 ms); and intraventricular dyssynchrony in 30 patients. Over the follow-up period of 12.1 +/- 8.7 months, 20 (29.9%) of 67 patients presented with at least one hemodynamic event: hospitalization for CHF in 19 (28%) of 67, HT in 2 (3%) of 67, and CHF death in 7 (10%) 67. Univariate analysis identified NYHA class (P = .03), LVEF (P = .015), IV dyssynchrony before (P = .038) and after CRT (P = .0035), IV delay after CRT (P = .002), 6-minute walk distance (P = .01), and DSE Res+ (P = .008) as significant predictors of clinical events. A receiver operating curve established a cut-off value of 1.25 for the DSE responders (Res+: 34 patients at 10 microg/kg/min infusion rates), and the improvement at the 10 microg/kg/min level was 41% +/- 7% in Res+ and 29% +/- 8% in nonresponders (P<.0001). With a cut-off value of 1.25-fold the LVEF increase, the DSE test exhibits 70% sensitivity, 61.7% specificity, 43.8% positive predictive value, and 82.9% negative predictive value. Cox analysis identified IV dyssynchrony before CRT (P = .01) and DSE Res+ (P = .003) as independent predictive factors.

CONCLUSIONS

Independent predictive factors of severe hemodynamic clinical outcome in patients with CRT are IV dyssynchrony and DSE.