Yoav Michowitz

Tel Aviv University, Tell Afif, Tel Aviv, Israel

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Publications (45)198.26 Total impact

  • Bernard Belhassen · Yoav Michowitz ·

    Heart rhythm: the official journal of the Heart Rhythm Society 10/2015; DOI:10.1016/j.hrthm.2015.10.020 · 5.08 Impact Factor
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    ABSTRACT: Elevated level of antibodies to oxidized low-density lipoproteins (OxLDL-Ab) was shown to reliably predict morbidity and mortality in patients with heart failure (HF). Two hundred and eleven patients aged ≥65 years treated at the Heart Failure Unit, Tel Aviv-Sourasky Medical Center, were included in this retrospective study. The end points were time to the first hospitalization (morbidity), all-cause mortality, and a combination of the two (composite outcome). HF duration ranged from 8 to 10.5 years. Mean follow-up was 5.2 ± 1.9 years. The mean number of clinical visits was 18.3 ± 2.4. Participants were divided according to OxLDL-Ab level. Group 1 had Ox LDL-Ab level <200 arbitrary U/ml. Group 2 had OxLDL-Ab level ≥200 arbitrary U/ml. The mean time to the first hospitalization was 25.8 ± 17.0 months. The mortality rate was 44.1%. Combined mortality and hospitalization rate was 58.8%. Adjusted hazard ratios of OxLDL-Ab for hospitalization were 3.16, p <0.001, 95% confidence interval 1.740 to 5.736 and for composite outcome 2.67, p <0.001, 95% confidence interval 1.580 to 4.518. In conclusion, OxLDL-Ab level was the best predictor for both hospitalization and composite outcome. It may, thus, serve as a useful clue for early and more accurate detection of poorly controlled HF and as a marker for imminent exacerbations of thereof.
    The American journal of cardiology 09/2015; 116(9). DOI:10.1016/j.amjcard.2015.07.053 · 3.28 Impact Factor
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    ABSTRACT: Background: -Information on long-term clinical outcome of patients with Brugada syndrome (BrS) treated with electrophysiologically (EP)-guided class 1A antiarrhythmic drugs (AAD) is limited. Methods and results: -An aggressive protocol of programmed ventricular stimulation (PVS) was performed in 96 BrS patients (88% males, mean age 39.8±15.9 years). Ten patients were cardiac arrest survivors, 27 had presented with syncope and 59 were asymptomatic. Ventricular fibrillation (VF) was induced in 66 patients, including 100%, 74%, and 61% of patients with cardiac arrest, syncope and no symptoms, respectively. All but 6 of the 66 patients with inducible VF underwent EP testing on quinidine (n=54), disopyramide (n=2) or both (n=4). Fifty four (90%) patients were EP-responders to ≥ 1 AAD with similar efficacy rates (≈90%) in all patients groups. Patients with no inducible VF at baseline were left on no therapy. After a mean follow-up of 113.3±71.5 months 92 patients were alive while 4 died from non cardiac causes. No arrhythmic event occurred during class 1A AAD therapy in any of EP-drug responders and in patients with no baseline inducible VF. Arrhythmic events occurred in only 2 cardiac arrest survivors treated with ICD alone but did not recur on quinidine. All cases of recurrent syncope (n=12) were attributed to a vasovagal (n=10) or non-arrhythmic mechanism (n=2). Class 1A AAD therapy resulted in 38% incidence of side effects that resolved after drug discontinuation. Conclusions: -Our data suggest that EP-guided class 1A AAD treatment has a place in our therapeutic armamentarium for all types of BrS patients.
    Circulation Arrhythmia and Electrophysiology 09/2015; DOI:10.1161/CIRCEP.115.003109 · 4.51 Impact Factor
  • Bernard Belhassen · Yoav Michowitz ·

    Circulation Arrhythmia and Electrophysiology 08/2015; 8(4):757-9. DOI:10.1161/CIRCEP.115.003138 · 4.51 Impact Factor
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    05/2015; 1(5). DOI:10.1016/j.hrcr.2015.04.010
  • Yoav Michowitz · Bernard Belhassen ·
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    ABSTRACT: Atrial fibrillation is the most common sustained arrhythmia and its prevalence increases significantly with age. This editorial discusses the review by Laish-Farkash et al. regarding ablation of atrial fibrillation, especially in the elderly, as well as new ablation modalities.
    Harefuah 07/2014; 153(7):394-6, 433.
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    ABSTRACT: There is a paucity of data on biophysical parameters during radiofrequency ablation of scar-mediated ventricular tachycardia (VT).
    Journal of Cardiovascular Electrophysiology 06/2014; · 2.96 Impact Factor
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    ABSTRACT: Background There is a paucity of data on biophysical parameters during radiofrequency ablation of scar-mediated ventricular tachycardia (VT).Methods and ResultsData was collected from consecutive patients undergoing VT ablation with open-irrigation. Complete data was available for 372 lesions in 21 patients. The frequency of biophysical parameter changes were: >10Ω reduction (80%), bipolar EGM reduction (69%), while loss of capture was uncommon (32%). Unipolar injury current was seen in 72% of radiofrequency applications. Both EGM reduction and impedance drop were seen in 57% and a change in all 3 parameters was seen in only 20% of lesions. Late potentials were eliminated in 33%, reduced/modified in 56%, and remained after ablation in 11%. Epicardial lesions exhibited an impedance drop (90% vs 76%, p = 0.002) and loss of capture (46% vs 27%, p<0.001) more frequently than endocardial lesions. Lesions delivered manually exhibited a >10Ω impedance drop (83% vs 71%, p = 0.02) and an EGM reduction (71% vs 40%, p< 0.001) more frequently than lesions applied using magnetic navigation, although loss of capture, elimination of LPs, and a change in all 3 parameters were similarly observed.ConclusionsVT ablation is inefficient as the majority of radiofrequency lesions do not achieve more than one targeted biophysical parameter. Only one-third of RF applications targeted at LPs result in complete elimination. Epicardial ablation within scar may be more effective than endocardial lesions and lesions applied manually may be more effective than lesions applied using magnetic navigation. New technologies directed at identifying and optimizing ablation effectiveness in scar are clinically warranted.This article is protected by copyright. All rights reserved.
    Journal of Cardiovascular Electrophysiology 06/2014; 25(11). DOI:10.1111/jce.12477 · 2.96 Impact Factor
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    ABSTRACT: -Cardiac tamponade is the most dramatic complication observed during atrial fibrillation (AF) ablation and the leading cause of procedure-related mortality. Female gender is a known risk factor for complications during AF ablation; however, it is unknown whether women have a higher risk of tamponade. -A systematic Medline search was used to locate academic electrophysiologic (EP) centers that reported cases of tamponade occurring during AF ablation. Centers were asked to provide information on cases of acute tamponade according to gender and their mode of management including any case of related mortality. Nineteen EP centers provided information on 34,943 ablation procedures involving 25,261 (72%) males. Overall 289 (0.9%) cases of tamponade were reported: 120 (1.24%) in females and 169 (0.67%) in males (odds ratio 1.83, P<0.001). There was a reciprocal association between center volume and the occurrence of tamponade with substantial lower risk in high volume centers. Most cases of tamponade occurred during catheter manipulation or ablation; females tended to develop more tamponades during transseptal catheterization. No gender difference in the mode of management was observed. However, 16% cases of tamponade required surgery with lower rates in high volume centers. Three cases of tamponade (1%) culminated in death. -Tamponade during AF ablation procedures is relatively rare. Women have an almost twofold higher risk for developing this complication. The risk of tamponade among women decreases substantially in high volume centers. Surgical back-up and acute management skills for treating tamponade are important in centers performing AF ablation.
    Circulation Arrhythmia and Electrophysiology 02/2014; 7(2). DOI:10.1161/CIRCEP.113.000760 · 4.51 Impact Factor
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    ABSTRACT: Transcatheter aortic valve implantation (TAVI) frequently requires postprocedural permanent pacemaker (PPM) implantation. We evaluated clinical and hemodynamic impact of PPM after TAVI. Clinical and echocardiographic data were retrospectively analyzed in 230 consecutive patients who underwent TAVI and echocardiography at baseline and after 6 months. Echocardiographic parameters included left ventricular ejection fraction (LVEF), left ventricular (LV) stroke volume, early mitral velocity/annulus velocity ratio (E/e'), right ventricular index of myocardial performance, systolic pulmonary artery pressure (SPAP), and aortic, mitral, and tricuspid regurgitation grades. Clinical outcomes included 2-year survival and cardiovascular and PPM-related event-free survival. The Medtronic CoreValve and Edwards Sapien prosthesis were used in 201 and 29 patients, respectively. PPM was required in 58 patients (25.4%). Two-year and event-free survival rates were similar between patients with and without PPM. At 6 months, patients with PPM demonstrated attenuated improvement in LVEF (-0.9 ± 8.7% vs 2.3 ± 10.8%, respectively, p = 0.03) and LV stroke volume (-2 ± 16 vs 4 ± 10 ml/m(2), respectively, p = 0.015), a trend toward smaller reduction in systolic pulmonary artery pressure (-1 ± 12 vs -6 ± 10 mm Hg, respectively, p = 0.09), and deterioration of right ventricular index of myocardial performance (-3 ± 17% vs 5 ± 26%, respectively, p = 0.05). The differences in post-TAVI aortic, mitral, and tricuspid regurgitation grades were insignificant. In conclusion, PPM implantation after TAVI is associated with reduced LVEF and impaired LV unloading. However, this unfavorable hemodynamic response does not affect the 2-year clinical outcome. The maintenance of clinical benefit appears to be driven by TAVI-related recovery of LV and right ventricular performance that mitigates unfavorable impact of PPM.
    The American journal of cardiology 10/2013; 113(1). DOI:10.1016/j.amjcard.2013.09.030 · 3.28 Impact Factor
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    Journal of the American College of Cardiology 03/2013; 61(10). DOI:10.1016/S0735-1097(13)60878-5 · 16.50 Impact Factor
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    ABSTRACT: Background During radiofrequency (RF) ablation of paroxysmal atrial fibrillation (PAF), a circular multielectrode recording “lasso” catheter is generally positioned inside each pulmonary vein (PV) to determine when PV potentials (PVP) are present and when they have have been ablated. The new circular irrigated-multipolar ablation-catheter (nMARQ) is positioned in the left atrium to create contiguous circular ablation lines around each PV ostium. Objectives To determine if the recordings obtained from the nMARQ catheter position around the PV ostium accurately reproduce the recordings obtained from a lasso catheter positioned within that vein. Methods In 10 patients undergoing RFA of PAF, we placed an nMARQ and a lasso catheter around and within each PV, respectively. Recordings obtained from both catheters at baseline and following RF ablation were compared. Results At baseline, recordings of PVPs in both catheters were concordant in 92% of all PVs. However, following RF delivery, the concordance between the nMARQ and lasso recordings was poor. The discordant result most commonly observed was disappearance of “PVPs” from the nMARQ with persistence of PVPs in the lasso (12/39, 30%). Conversely, delivery of RF frequently resulted in fragmented electrograms (pseudo-PVPs) on the nMARQ despite evidence of PV isolation by lasso catheter recordings. Conclusions Use of an nMARQ catheter alone, as currently recommended, may lead to under-estimation and over-estimation of the number of RF applications required to achieve PV isolation.
    Heart rhythm: the official journal of the Heart Rhythm Society 01/2013; 11(4). DOI:10.1016/j.hrthm.2013.12.029 · 5.08 Impact Factor
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    ABSTRACT: BACKGROUND: Epicardial ablation has been shown to be a useful adjunct for treatment of ventricular tachycardia (VT). OBJECTIVE: To report the trends, safety and efficacy of epicardial mapping and ablation at a single center over an eight-year period. METHODS: Patients referred for VT ablation (6/2004-6/2011) were divided into three groups: ischemic cardiomyopathy (ICM), nonischemic cardiomyopathy (NICM), and idiopathic ventricular arrhythmias (VA). Scar-mediated VT patients that underwent combined epicardial and endocardial (epi-endo) mapping and ablation were compared with those that underwent endocardial ablation only (endo-only) with regards to patient characteristics, acute procedural success, 6 month and 12 month clinical outcomes. RESULTS: Amongst 144 patients referred for VT ablation, 95 patients underwent 109 epicardial procedures (94% access rate). Major complications were seen in 8 patients (8.8%) with pericardial bleeding (>80cc) in 6 cases (6.7%), although no tamponade, surgical intervention, or procedural mortality was seen. Patients with ICM who underwent a combined epi-endo ablation had improved freedom from VT compared to those with endo-only ablation at 12 months (85% vs 56%, p=0.03). In NICM patients, no differences were seen between those that underwent epi-endo ablation compared to those with endo-only ablation at 12 months (36% vs 33%, p=1.0). In idiopathic VA, only 2/17 patients were successfully ablated from the epicardium. CONCLUSIONS: In this large tertiary single-center experience, complication rates are acceptably low and improved clinical outcomes were associated with epi-endo ablation in ICM patients. NICM patients represent a growing referred population, although clinical recurrence remains high despite epicardial ablation. Epicardial ablation has a low yield in idiopathic VA.
    Heart rhythm: the official journal of the Heart Rhythm Society 12/2012; 10(4). DOI:10.1016/j.hrthm.2012.12.013 · 5.08 Impact Factor
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    Circulation Arrhythmia and Electrophysiology 10/2012; 5(5):e101. DOI:10.1161/CIRCEP.112.974626 · 4.51 Impact Factor
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    ABSTRACT: Introduction: The usefulness of unipolar electrograms (EGMs) has been reported in assessing lesion transmurality and conduction block along ablation lines. It is unknown whether unipolar and bipolar EGM characteristics predict exit block during pulmonary vein isolation (PVI) procedures. Methods and results: Twenty patients (63 ± 7 years; 14 males [70%]) undergoing PVI with a circular mapping catheter (CMC) placed outside each PV ostium were retrospectively studied. After entrance block was achieved, pacing at each bipole around the CMC was performed to assess for absence of atrial capture (exit block). Bipolar EGMs recorded before pacing were examined for voltage, duration, fractionation, and monophasic morphology. Unipolar EGMs were examined for positive and negative amplitude, PQ segment elevation, fractionation, and monophasic morphology. The association of these parameters with atrial capture (absence of exit block) at each site was analyzed. After achievement of entrance block, only 23 of 64 PV antra (36%) exhibited exit block. Unipolar EGMs at sites with persistent capture were more likely to be fractionated and had larger negative deflections. Bipolar EGMs at sites with persistent capture showed higher amplitude, longer duration, were more likely to be fractionated, and were less likely to be monophasic. In a multivariate logistic regression model, bipolar and unipolar fractionation, bipolar duration, and lack of bipolar monophasic morphology were independently associated with persistent atrial capture. Conclusion: Specific unipolar and bipolar EGM characteristics are associated with left atrium capture after PV antral isolation. These parameters might be useful in predicting the need for further ablation to achieve exit block.
    Pacing and Clinical Electrophysiology 08/2012; 35(11). DOI:10.1111/j.1540-8159.2012.03499.x · 1.13 Impact Factor
  • Yoav Michowitz · Roderick Tung · Charles Athill · Kalyanam Shivkumar ·
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    ABSTRACT: Ventricular tachycardia as a late complication of blunt chest trauma has never been reported. We present a case of combined endocardial and epicardial delineation of the right ventricular arrhythmogenic substrate, where other causes of cardiomyopathy were excluded. The epicardial scar was more extensive than endocardial scar, and the central isthmus was likely intramural. A history of blunt chest trauma should be considered in patients with right ventricular cardiomyopathy. (PACE 2012; 35:e127e130)
    Pacing and Clinical Electrophysiology 05/2012; 35(5):e127-30. DOI:10.1111/j.1540-8159.2011.03121.x · 1.13 Impact Factor
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    ABSTRACT: Myocardial scars harbor areas of slow conduction and display abnormal electrograms. Pace-mapping at these sites can generate a 12-lead ECG morphological match to a targeted ventricular tachycardia (VT), and in some instances, multiple exit morphologies can result. At times, this can also result in the initiation of VT, termed pace-mapped induction (PMI). We hypothesized that in patients undergoing catheter ablation of VT, scar substrates with multiple exit sites (MES) identified during pace-mapping have improved freedom from recurrent VT, and PMI of VT predicts successful sites of termination during ablation. High-density mapping was performed in all subjects to delineate scar (0.5-1.5 mV). Sites with abnormal electrograms were tagged, stimulated (bipolar 10 mA at 2 ms), and targeted for ablation. MES was defined as >1 QRS morphology from a single pacing site. PMI was defined as initiation of VT during pace-mapping (400-600 ms). In a 2-year period, 44 consecutive patients with scar-mediated VT underwent mapping and ablation. MES were observed during pace-mapping in 25 patients (57%). At 9 months, 74% of patients who exhibited MES during pace-mapping had no recurrence of VT compared with 42% of those without MES observed (P=0.024), with an overall freedom from VT of 61%. Thirteen patients (30%) demonstrated PMI, and termination of VT was seen in 95% (18/19) of sites where ablation was performed. During pace-mapping, electrograms that exhibit MES and PMI may be specific for sites critical to reentry. These functional responses hold promise for identifying important sites for catheter ablation of VT.
    Circulation Arrhythmia and Electrophysiology 02/2012; 5(2):264-72. DOI:10.1161/CIRCEP.111.967976 · 4.51 Impact Factor

  • Pacing and Clinical Electrophysiology 08/2011; 35(1):97-9. DOI:10.1111/j.1540-8159.2011.03188.x · 1.13 Impact Factor
  • Tara Bourke · Nilesh Mathuria · Yoav Michowitz · Kalyanam Shivkumar ·

    Future Cardiology 05/2011; 7(3):273-6. DOI:10.2217/fca.11.15
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    ABSTRACT: The utility of defibrillation threshold testing in patients undergoing implantable cardioverter-defibrillator (ICD) implantation is controversial. Higher defibrillation thresholds have been noted in patients undergoing implantation of cardiac resynchronization therapy defibrillators (CRT-D). Since the risks and potential benefits of testing may be higher in this population, we sought to assess the impact of defibrillation safety margin or vulnerability safety margin testing in CRT-D recipients. A total of 256 consecutive subjects who underwent CRT-D implantation between January 2003 and December 2007 were retrospectively reviewed. Subjects were divided into two groups based on whether (n= 204) or not (n= 52) safety margin testing was performed. Patient characteristics, tachyarrhythmia therapies, procedural results, and clinical outcomes were recorded. Baseline characteristics, including heart failure (HF) severity, were comparable between the groups. Four cases of HF exacerbation (2%), including one leading to one death, were recorded in the tested group immediately post-implantation. No complications were observed in the untested group. After a mean follow-up of 32 ± 20 months, the proportion of appropriate shocks in the two groups was similar (31 vs. 25%, P = 0.49). There were three cases of failed appropriate shocks in the tested group, despite adequate safety margins at implantation, whereas no failed shocks were noted in the untested group. Survival was similar in the two groups. Defibrillation efficacy testing during implant of CRT-D was associated with increased morbidity and did not predict the success of future device therapy or improve survival during long-term follow-up.
    Europace 04/2011; 13(5):683-8. DOI:10.1093/europace/euq519 · 3.67 Impact Factor

Publication Stats

781 Citations
198.26 Total Impact Points


  • 2004-2015
    • Tel Aviv University
      • • Department of Internal Medicine
      • • Department of Computer Science
      Tell Afif, Tel Aviv, Israel
  • 2009-2014
    • University of California, Los Angeles
      • Division of Cardiology
      Los Ángeles, California, United States
  • 2005-2013
    • Tel Aviv Sourasky Medical Center
      • Department of Cardiology
      Tell Afif, Tel Aviv, Israel
    • Assaf Harofeh Medical Center
      Ayun Kara, Central District, Israel