Caroline Medi

Royal Melbourne Hospital, Melbourne, Victoria, Australia

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Publications (55)122.16 Total impact

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    ABSTRACT: -Successful arrhythmia ablation normalizes ejection fraction (EF) in tachycardia-mediated cardiomyopathy (TMC), but recurrent heart failure and late sudden death have been reported. The aim of this study was to characterize the left ventricle (LV) of TMC patients long after definitive arrhythmia cure. -Thirty-three patients with a history of successfully ablated incessant focal atrial tachycardia 64±36 months prior, and 20 healthy controls were recruited. At ablation, 18 patients had EF<50% (AT-Low EF) that recovered within 3 months from 37±12 to 56±4% (p<0.001), while 15 patients had EF>55% (AT-Normal EF). No subjects had EF of 50% to 55%. Subjects underwent echocardiography with speckle tracking and contrast-enhanced cardiac magnetic resonance imaging (CMR) with ventricular T1 mapping as an index of diffuse fibrosis. CMR was performed using a clinical 1.5-T scanner and 0.2 mmol/kg gadolinium-DTPA for contrast. Subject characteristics were similar across the 3 groups. Compared to AT-Normal EF patients and controls, AT-Low EF patients had lower EF (60±6 vs 64±4 and 65±4%, p<0.05), greater indexed LV end-diastolic volume (102±34 vs 84±14 and 85±16 ml/m(2), p<0.05), and greater indexed LV end-systolic volume (41±11 vs 31±7 and 3±8 ml/m(2), p<0.01) on CMR. Compared to controls, AT-Low EF patients had reduced global LV corrected T1 time (442±53 vs 529±61, p<0.05) consistent with diffuse fibrosis. -TMC patients exhibit differences in LV structure and function including diffuse fibrosis long after arrhythmia cure, indicating that recovery is incomplete.
    Circulation Arrhythmia and Electrophysiology 07/2013; · 5.95 Impact Factor
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    ABSTRACT: Atrial fibrillation (AF) and systolic heart failure (HF) frequently coexist. Restoration of sinus rhythm by catheter ablation may result in a variable improvement in left ventricular (LV) function. Late gadolinium enhancement (LGE) on cardiac magnetic resonance (CMR) imaging identifies irreversible structural change and may predict incomplete recovery of LV function. We prospectively selected AF and symptomatic HF patients without LV LGE and report the impact of AF ablation on LV function. Patients with AF and symptomatic HF (LV EF<50%) resistant to at least one antiarrhythmic drug and prior electrical cardioversion underwent contrast-enhanced CMR. LGE negative patients underwent pulmonary vein isolation and left atrial roof line with continued antiarrhythmic medications until follow-up CMR 6 months post-ablation. Sixteen patients (aged 52±11 years, mean AF duration 37±39 months, LA size 44±13 ml/m(2)) underwent AF ablation. At 6 months, 15 of 16 patients maintained sinus rhythm and underwent CMR. LV EF increased from 40±10% at baseline to 60±6% (p<0.001) and LV end systolic volume index decreased from 52±12 to 36±9 ml/m(2) (p<0.001). Left atrial size decreased from 44±13 to 36±11 ml/m(2) (p<0.01). In patients with AF and LV dysfunction in the absence of LGE on CMR, ventricular function normalizes following the restoration of sinus rhythm. CMR may assist in the selection of AF-HF patients most likely to benefit from catheter ablation.
    Heart rhythm: the official journal of the Heart Rhythm Society 06/2013; · 4.56 Impact Factor
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    ABSTRACT: OBJECTIVES: This study sought to determine whether post-operative neurocognitive dysfunction (POCD) occurs following AF ablation. BACKGROUND: Ablation for atrial fibrillation (AF) is a highly effective strategy, however the risk of transient ischaemic attack and stroke is approximately 0.5-1%. In addition MRI studies report a 7-14% incidence of silent cerebral infarction. Whether cerebral ischaemia results in POCD after AF ablation is not well-established. METHODS: The study included 150 patients: 60 patients undergoing ablation for paroxysmal AF (PAF); 30 patients undergoing ablation for persistent AF n=30 (PeAF) and 30 patients undergoing ablation for supraventricular tachycardia (SVT) were compared to a matched non-operative control group of patients with AF awaiting radiofrequency ablation (n=30). Patients were administered 8 neuropsychological tests administered at baseline and at 2 days and 3 months post-operatively. Tests were administered at the same time-points to the non-operative control group. Reliable change index was used to calculate POCD. RESULTS: The incidence of POCD at day 2 post-procedure was 28% in patients with PAF; 27% in patients with PeAF; 13% in patients with SVT; and 0% in AF control patients (p=0.007). At day 90, the incidence of POCD in patients with PAF was 13%, 20% in patients with PeAF; 3% in patients with SVT, and 0% in AF control patients (p=0.03). When analyzing the 3 procedural groups together, 29/120 (24%) patients manifest POCD at day 2 and 15/120 (13%) at day 90 post ablation procedure; p=0.029. On univariate analysis increasing LA access time was associated with POCD at day 2 (p=0.04) and day 90 (p=0.03) CONCLUSIONS: Ablation for atrial fibrillation is associated with a 13-20% incidence of POCD in patients with AF at long-term follow up. These results were seen in a population of predominantly CHADS2 0-1 patients who represent the majority of patients undergoing AF ablation. The long-term implications of these subtle changes require further study.
    Journal of the American College of Cardiology 05/2013; · 14.09 Impact Factor
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    ABSTRACT: Left Septal Atrial Tachycardias. Objective: The objective was to characterize the electrocardiographic and electrophysiological features of focal atrial tachycardia (FAT) originating from the left septum (LS). Background: FAT is recognized to occur at predefined anatomic locations rather than randomly throughout the atria. We describe the ECG and EP features of ATs originating from the LS as an important site for apparent perinodal tachycardias. Methods: Nine patients presenting with LS FAT from a consecutive series of 384 underwent EP/RFA for symptomatic FAT. Results: The mean age was 56 ± 12 years; 7 female with symptoms for 36 ± 28 months. P wave morphology (PWM) was negative/positive in lead V1 and across the precordial leads and negative or negative/positive in inferior leads in all patients. Tachycardia was incessant in 6 out of 9 patients with a mean tachycardia cycle length 421 ± 56 milliseconds. His A was ahead of P wave in all patients (mean -15 ± 5 milliseconds) and earlier than CS proximal (mean 4 ± 9 milliseconds). Successful acute focal ablation achieved at a mean of 31 ± 12 milliseconds ahead of P wave with no recurrences at a mean follow-up of 30 ± 28 months. Conclusion: Although the left septum is an uncommon site for focal AT an awareness of this location for harboring foci is particularly important when mapping apparently right-sided septal tachycardias. (J Cardiovasc Electrophysiol, Vol. pp. 1-6).
    Journal of Cardiovascular Electrophysiology 11/2012; · 3.48 Impact Factor
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    ABSTRACT: Atrial fibrillation (AF) is the most common sustained cardiac arrhythmia in human beating hearts. AF initiates self-perpetuating changes in electrophysiology, structure and functional properties of the atria, a phenomenon known as atrial remodeling. Hypertension, heart failure, valvular heart disease, sleep apnea, congenital heart disease are well known risk factors for AF that contribute to the development of atrial substrate. There is some evidence that reversal of atrial remodeling is possible with correction of antecedent conditions, however the timing of the intervention or upstream therapy may be critical. This review will describe the pathophysiology of atrial remodeling as it pertains to AF. We will describe components of remodeling including changes in atrial refractoriness, conduction and atrial structure, in addition to autonomic changes and anatomic factors that predispose to remodeling. We will discuss our current understanding of the electrophysiological changes that contribute to AF persistence. We will describe nature of atrial and pulmonary vein remodeling in the context of different forms of AF, with and without predisposing risk factors. We will describe the nature of remodeling over time following therapeutic interventions such as AF ablation in order to show that it does not necessarily improve and may worsen.
    Progress in Biophysics and Molecular Biology 08/2012; · 2.91 Impact Factor
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    ABSTRACT: Atrial Remodeling in Atrial Flutter. Introduction: Atrial fibrillation (AF) and atrial flutter (AFL) are related arrhythmias with common triggers, yet in individual patients either AF or AFL often predominates. We performed detailed electrophysiologic (EP) and electroanatomic (EA) studies of the right atrium (RA) in patients with AF and AFL to determine substrate differences that may explain the preferential expression of AF/AFL in individual patients. Methods: Patients with AF (n = 13) were compared to patients with persistent AFL (n = 10). Detailed studies were performed, and 3-dimensional electroanatomic mapping studies were created and the RA was divided into 4 segments for regional analysis. Global, septal, lateral, anterior, and posterior segments were compared for analysis of: bipolar voltage; proportion of low-voltage areas and areas of electrical silence; conduction times; and proportion of abnormal signals (fractionated signals and double potentials). Results: Compared to patients with AF, patients with AFL had (1) lower bipolar voltage and an increase in the proportion of low-voltage areas; (2) an increase in the proportion of complex signals; and (3) prolongation of activation times. Conclusions: Patients with AFL showed more advanced remodeling than patients with AF with slowed conduction, lower voltage areas with regions of electrical silence, and a greater proportion of complex signals, particularly in the posterior RA. These changes facilitate the stabilization of AFL and may explain why some patients are more likely to develop AFL as a sustained clinical arrhythmia. (J Cardiovasc Electrophysiol, Vol. 23 pp. 1067-1072, October 2012).
    Journal of Cardiovascular Electrophysiology 04/2012; 23(10):1067-72. · 3.48 Impact Factor
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    ABSTRACT: Pulmonary hypertension (PH) is common to a range of cardiopulmonary conditions and is associated with atrial arrhythmias. However, little is known of the isolated atrial effects of PH and right atrial dilatation (RA) in humans. To avoid the confounding effects of PH-associated disease states, we performed detailed electrophysiological (EP) and electroanatomic (EA) mapping of the RA in patients with idiopathic PH. Eight PH patients (mean pulmonary arterial [PA] pressure 39.0 ± 15.8 mmHg) and 16 age-matched controls (mean PA pressure 11.5 ± 4.1 mmHg, P < 0.0001) were studied. Corrected sinus node recovery times (cSNRT), atrial effective refractory periods (ERPs), conduction delay at the crista terminalis (CT), and inducibility of atrial fibrillation (AF) were evaluated. EA mapping (pacing cycle length 600 and 300 milliseconds) was performed to determine RA global and regional voltage, conduction velocities, atrial activation times, fractionated electrograms and double potentials. Patients with PH demonstrated a prolongation in cSNRT without significant change in atrial ERP and an increase in AF inducibility. PH was associated with lower tissue voltage (1.8 ± 0.4 mV in PH vs 2.2 ± 0.4 mV in controls, P = 0.02), increased low voltage areas (13.7 ± 8.2% in PH vs 6.2 ± 3.7% in controls, P < 0.01) and the presence of electrically silent areas. Conduction velocities were slower (global 67.3 ± 5.6 cm/s vs 92.8 ± 4.0 cm/s, P < 0.001) and fractionated electrograms and double potentials were more prevalent (14.7 ± 4.4% vs 6.3 ± 4.1, P < 0.01) in PH compared with controls, respectively. Idiopathic PH is associated with RA remodeling characterized by: generalized conduction slowing with marked regional abnormalities; reduced tissue voltage; and regions of electrical silence. These changes provide important insights into the isolated effects of PH fundamental to a range of clinical conditions associated with AF.
    Journal of Cardiovascular Electrophysiology 01/2012; 23(6):614-20. · 3.48 Impact Factor
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    ABSTRACT: Whether curative ablation can prevent progression of the atrial electroanatomic remodeling associated with atrial fibrillation (AF) is not known. The purpose of this study was to determine whether successful radiofrequency ablation (RFA) of AF can prevent progression of the atrial substrate associated with AF. Detailed right atrial electroanatomic maps from 11 patients without apparent structural heart disease undergoing RFA of AF at baseline and ≥6 months following successful RFA were compared to 11 control patients undergoing electrophysiologic evaluation of supraventricular tachycardia. Bipolar voltage, conduction, effective refractory periods (ERPs), and signal complexity were assessed. At baseline compared with the control group, the AF group demonstrated (1) lower voltage (P <.001); (2) slowed conduction (P = .005); (3) more prevalent complex signals (P <.001); (4) prolonged regional refractoriness (P <.05), and (5) left atrial dilation (P = .01). At 10 ± 13 month follow-up, the AF group demonstrated the following compared to baseline: (1) lower voltage (P <.05); (2) either no improvement or further slowing of conduction; (3) further prolongation of regional refractoriness (P <.05); and (4) reversal of left atrial dilation (P <.05). Patients with lone AF demonstrate evidence of an abnormal atrial substrate at baseline compared to control patients without AF. This substrate does not appear to reverse even after successful catheter ablation. These findings may have implications for long-term outcomes of ablation and for timing of ablative intervention.
    Heart rhythm: the official journal of the Heart Rhythm Society 11/2011; 9(4):473-80. · 4.56 Impact Factor
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    ABSTRACT: Increasing age is a significant risk factor for developing atrial fibrillation (AF). Pulmonary vein (PV) triggers are critical in the mechanism of AF, but little is known of the substrate changes that occur within the PVs with ageing. Therefore, we sought to identify whether ageing is associated with electroanatomic changes within the pulmonary veins. Twenty-five patients undergoing ablation for left-sided supraventricular tachycardia had high-density 3D electroanatomic maps of all four PVs created. Patients were divided into two groups: group 1 aged <50 years and group 2 aged >50 years. Mean-voltage (MV), % low-voltage (LV < 0.5 mV), conduction, signal complexity, and PV muscle sleeve length and diameter were assessed. Age was 33 ± 8 vs. 66 ± 8 years for groups 1 and 2, respectively (P < 0.001). Group 2 demonstrated: (i) lower MV within the PVs (1.66 ± 1.1 vs. 1.88 ± 1.1 mV, P < 0.001); (ii) increased % LV (5.0 vs. 1.1%, P < 0.001), and increased voltage heterogeneity within the PVs (65 ± 14 vs. 55 ± 8%, P < 0.05); (iii) regional and global conduction slowing in the PVs; and (iv) increased % complex signals within the PVs (1.4 vs. 0.4%, P = 0.009). There was no difference in PV sleeve length or diameter. Increasing age is associated with PV electroanatomic changes characterized by a significant reduction in PV voltage, conduction slowing, and increasing signal complexity. These observations provide new insights into the potential mechanisms behind the increased prevalence of AF with advancing age.
    Europace 08/2011; 14(1):46-51. · 2.77 Impact Factor
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    ABSTRACT: Mapping of atrial fibrillation (AF) involves identification of low-voltage regions associated with complex fractionated electrograms (CFE) which theoretically represent abnormal substrate and targets for ablation. Whether low-voltage CFE areas also identify abnormal substrate during paced rhythm is unknown. Twelve patients with persistent AF undergoing ablation of AF had high-density three-dimensional electroanatomic maps created during AF and paced rhythm (24 maps) and the mean voltage during AF and paced rhythm was compared for eight segments of the left atrium (LA). The following were correlated during AF and paced rhythm: regional mean voltage; %low voltage (defined as <0.5 mV); and extent of CFE. In addition, the relationship between the extent of CFE in AF: (i) %low voltage and (ii) conduction during paced rhythm were determined. Mean voltage was lower during AF than paced rhythm for all regions and globally (0.7 ± 0.2 mV vs. 2.1 ± 0.6 mV, P < 0.001). The regional and overall %low voltage of the LA was greater during AF than paced rhythm (53 ± 19% vs. 9 ± 2%, P < 0.001). There was no correlation between mean voltage or %low voltage during AF and paced rhythm. Complex fractionated electrograms were prevalent throughout all regions during AF, but did not correlate with %low voltage, fractionation, or slowed conduction during paced rhythm. Areas of CFE and low voltage recorded during AF frequently demonstrate normal atrial myocardial characteristics (normal conduction, electrograms, and voltage) during sinus rhythm. Therefore, AF CFE sites do not necessarily identify regions of an abnormal atrial substrate. However, this does not exclude the possibility that CFE might identify a focal driver or source occurring in a region of normal atrial myocardium.
    Europace 06/2011; 13(12):1709-16. · 2.77 Impact Factor
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    ABSTRACT: Pulmonary veins play an important role in triggering atrial fibrillation (AF). Pulmonary vein isolation (PVI) is an effective treatment for patients with paroxysmal AF. However, the late AF recurrence rate in long-term follow-up of circumferential PV antral isolation (PVAI) is not well documented. We sought to determine the time to recurrence of arrhythmia after PVAI, and long-term rates of sinus rhythm after circumferential PVAI. One hundred consecutive patients with a mean age of 54 ± 10 years, with paroxysmal AF who underwent PVAI procedure were analyzed. Isolation of pulmonary veins was based on an electrophysiological and anatomical approach, with a nonfluoroscopic navigation mapping system to guide antral PVI. Ablation endpoint was vein isolation confirmed with a circular mapping catheter at first and subsequent procedures. Clinical, ECG, and Holter follow-up was undertaken every 3 months in the first year postablation, every 6 months thereafter, with additional prolonged monitoring if symptoms were reported. Time to arrhythmia recurrence, and representing arrhythmias, were documented. Isolation of all 4 veins was successful in 97% patients with 3.9 ± 0.3 veins isolated/patient. Follow-up after the last RF procedure was at a mean of 39 ± 10 months (range 21-66 months). After a single procedure, sinus rhythm was maintained at long-term follow-up in 49% patients without use of antiarrhythmic drugs (AADs). After repeat procedure, sinus rhythm was maintained in 57% patients without the use of AADs, and in 82% patients including patients with AADs. A total of 18 of 100 patients had 2 procedures and 4 of 100 patients had 3 procedures for recurrent AF/AT. Most (86%) AF/AT recurrences occurred ≤ 1 year after the first procedure. Mean time to recurrence was 6 ± 10 months. Kaplan-Meier analysis on antiarrhythmics showed AF free rate of 87% at 1 year and 80% at 4 years. There were no major complications. PVAI is an effective strategy for the prevention of AF in the majority of patients with PAF. Maintenance of SR requires repeat procedure or continuation of AADs in a significant proportion of patients. After maintenance of sinus rhythm 1-year post-PVAI, a minority of patients will subsequently develop late recurrence of AF.
    Journal of Cardiovascular Electrophysiology 02/2011; 22(2):137-41. · 3.48 Impact Factor
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    ABSTRACT: To report the major complication rate associated with pulmonary vein antral isolation (PVAI) in a consecutive series of 500 patients from a single center. Catheter ablation for atrial fibrillation (AF) is an established procedure for refractory AF. However, the risk of major complications has been reported to range from 3.9% to 4.5% and continues to represent a cause for concern. We hypothesized that these studies may have overestimated the rate of major complications associated with PVAI in patients with a low prevalence of structural heart disease (SHD). Data were prospectively collected from 500 consecutive AF ablation procedures on 424 patients (mean age 55 ± 11 years, 79% men, paroxysmal AF-80% and persistent AF-20%, CHADS₂ scores of 0, 1, 2, 3 present in 64%, 28%, 7%, 1%, respectively), performed between July 2006 and September 2009. All procedures were performed under general anesthesia with intraoperative transesophageal echo. PVAI was performed using a nonfluoroscopic mapping system with an endpoint of PV isolation. Adjunctive left atrial ablation was performed in 21% of patients only. Major complications were defined from a compilation of those reported in 5 prior studies reporting complications. In 500 procedures, there were no instances of death, stroke/TIA, cardiac tamponade, atrioesophageal fistula, or PV stenosis. Major complications occurred in 4 procedures (0.8%): esophageal hematoma (TEE probe)--2; pharyngeal trauma--1; and retroperitoneal hematoma-1. Conclusions: AF ablation can be performed safely in young patients without structural heart disease with a low risk (<1%) of major complications when using a strategy of PVAI.
    Journal of Cardiovascular Electrophysiology 02/2011; 22(2):163-8. · 3.48 Impact Factor
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    ABSTRACT: Pulmonary vein (PV) reconnection is the Achilles heel of pulmonary vein isolation (PVI) for atrial fibrillation (AF). Dissociated pulmonary vein potentials (dPVP) may reflect abnormal PV automaticity, indicate more extensive PV muscular sleeve or may simply be an epiphenomenon. This study sought to determine the incidence, characteristics and prognostic significance of dPVP following PVI for AF. 89 consecutive patients (mean age 58.2 ± 8.4 years, 75% male, 74% paroxysmal, 26% persistent AF) underwent antral PVI using three-dimensional mapping systems with image integration with the endpoint of bidirectional PV block. Following PV electrical isolation the presence and characteristics of dPVP were recorded. Holter monitoring was performed at 3, 6 and 12 months. Acute PV reconnection was assessed over a 30-min waiting period. Electrical isolation was achieved in all 372 PV targeted for ablation. 69 of 372 isolated PV (19%) demonstrated dPVP after acute electrical isolation. Sites of dPVP origin were the left superior in 36%, left inferior in 20%, right superior in 31% and right inferior in 12%. All 69 dPVP demonstrated slow activity (cycle length >1500 ms) with only four persisting more than 30 min after acute isolation. There was no difference in the clinical characteristics between dPVP-positive vs dPVP-negative patients. At a mean follow-up of 21 ± 8 months the single procedure success was 25/33 (76%) in dPVP-positive versus 39/60 (64%) in dPVP-negative patients (p = -0.3). In the eight dPVP-positive patients who underwent a second procedure, 11 of the 14 (79%) veins with initial dPVP demonstrated PV-left atrial reconnection. dPVP are present in 19% of PV following acute antral electrical isolation. The presence of dPVP did not predict recurrent AF following PVI.
    Heart (British Cardiac Society) 02/2011; 97(7):579-84. · 5.01 Impact Factor
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    ABSTRACT: In patients with surgical atrial septal defect (ASD) repair, late atrial flutters (AFLs), including cavotricuspid isthmus (CTI)-dependent and non-CTI-dependent scar-related flutter (AFL), are common. Radiofrequency ablation (RFA) of these arrhythmias has a high acute success rate. We aimed to characterize the long-term freedom from atrial arrhythmias in this population. Twenty consecutive patients undergoing RFA for AFL late after ASD repair were included. Electrophysiological assessment included multipolar activation, entrainment, and electroanatomic mapping. Clinical, electrocardiograph, and Holter monitoring follow-up was conducted every 6 months. Mean age was 53 ± 13 years. Time from surgical repair to RFA was 29 ± 15 years. All patients had CTI-dependent AFL (20/20). There were 1.6 ± 0.7 arrhythmias per patient; other arrhythmias included non-CTI-dependent AFL (14), focal atrial tachycardia (two), and atrioventricular nodal reentry tachycardia (two) . Acute success was obtained in 100%. Five patients with recurrent AFL (three CTI dependent, two non-CTI dependent) at 13 ± 8 months had successful repeat RFA. At 3.2 ± 1.6 years follow-up since the last procedure, 90% of patients with successful RFA for AFL remained free of their clinical arrhythmia. However, 30% of the original 20 patients had documented atrial fibrillation (AF) 2.1 ± 1.6 years after the last procedure; five (25%) required AF intervention. One stroke (5%) occurred in the context of late AF. RFA of AFL occurring late after surgical ASD repair has a low long-term risk of recurrence, although 25% of patients required two procedures. However, there is a high late incidence of AF (30%), with an additional 25% of patients requiring intervention for AF.
    Pacing and Clinical Electrophysiology 01/2011; 34(4):431-5. · 1.75 Impact Factor
  • Source
    Journal of The American College of Cardiology - J AMER COLL CARDIOL. 01/2011; 57(14).
  • Heart Lung and Circulation - HEART LUNG CIRC. 01/2011; 20.
  • Heart Lung and Circulation - HEART LUNG CIRC. 01/2011; 20.
  • Heart Lung and Circulation - HEART LUNG CIRC. 01/2011; 20.
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    ABSTRACT: Omega-3 polyunsaturated fatty acids in fish oils may have antifibrillatory effects. Their mechanism of action in humans is poorly understood. The purpose of this study was to investigate the effects of chronic fish oil supplementation on human atrial electrophysiology (EP). Two groups of patients without clinical AF or structural heart disease and fish intake ≤1/week were prospectively recruited into a control group (n = 30) and a fish oil group (n = 31). The latter were prescribed 6 g/day of fish oil for ≥1 month before an EP study. The following were compared at time of EP study: serum omega-3 levels; right atrial and coronary sinus effective refractory periods (ERPs); interatrial, intra-atrial, left atrial, and coronary sinus conduction at baseline and the maximal conduction delay with the shortest propagated extrastimulus; and inducibility of AF (10 inductions/patient). The following significant differences were noted favoring the fish oil group at time of EP: (1) twofold higher total omega-3 levels (P < .001); (2) lengthening of ERPs by 8%-14% at all measured sites and pacing cycle lengths (P < .05); (3) no effect on baseline interatrial, intra-atrial, left atrial, and coronary sinus conduction but a significant attenuation of maximal conduction delay (P < .05); (4) less inducible AF (AF ≥30 seconds: 24.2% vs. 7.9%; P < .001); (5) shorter mean duration of induced AF (P = .003); and (6) prolongation of induced AF cycle length (P < .001). Chronic fish oil supplementation in humans prolongs atrial refractoriness and reduces vulnerability to inducible AF. These EP changes may explain the antifibrillatory effect of chronic fish oil ingestion.
    Heart rhythm: the official journal of the Heart Rhythm Society 12/2010; 8(4):562-8. · 4.56 Impact Factor
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    ABSTRACT: BACKGROUND AND PURPOSE: Although the stroke rate associated with atrial fibrillation has declined over the last 10 years, the emerging atrial fibrillation epidemic threatens to increase the incidence of cardioembolic stroke. Summary of Review-Oral anticoagulants are superior antithrombotic agents but are underused due to fear of bleeding and uncertainty about which patients will benefit. Individualized decisions on antithrombotic therapy require balancing the competing risks of thromboembolism and bleeding. The CHADS₂ (Congestive heart failure, Hypertension, Age > 75 years, and Diabetes mellitus, and 2 points for prior Stroke/transient ischemic attack) score and other schemes provide an estimate of thromboembolic risk; however, the external validity of these estimates in the context of well-controlled risk factors, or a hypercoagulable state, is uncertain. Moreover, it is very difficult to estimate bleeding risk. Recent studies highlight the need for meticulous international normalized ratio control to achieve optimal outcomes hampered by the high bleeding risk during oral anticoagulant inception and other limitations of warfarin. Dabigatran is at least as efficacious as warfarin in preventing stroke and systemic embolism for patients in whom the risk of thromboembolism outweighs bleeding risk. In addition, the results of ongoing trials evaluating alternative anticoagulants such as oral anti-Xa agents are awaited. In this review, we discuss emerging therapies including available and completed trials of direct antithrombins and anti-Xa agents, including ximelagatran, idraparinaux, and dabigatran; and new device therapies including left atrial appendage occlusion devices. CONCLUSIONS: In light of these promising new therapies, it is likely that atrial fibrillation thromboembolism guidelines will need to be rewritten and frequently updated.
    Stroke 10/2010; 41(11):2705-13. · 6.16 Impact Factor

Publication Stats

266 Citations
122.16 Total Impact Points

Institutions

  • 2008–2013
    • Royal Melbourne Hospital
      Melbourne, Victoria, Australia
  • 2011–2012
    • Alfred Hospital
      Melbourne, Victoria, Australia
    • University of Melbourne
      • Royal Melbourne Hospital Clinical School
      Melbourne, Victoria, Australia
  • 2007–2010
    • Concord Repatriation General Hospital
      Sydney, New South Wales, Australia