Michael O Sweeney

Harvard University, Cambridge, Massachusetts, United States

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Publications (117)

  • Michael Owen Sweeney
    Article · Jun 2015 · Trends in cardiovascular medicine
  • Michael O Sweeney · Anne S Hellkamp · Rutger J van Bommel · [...] · Jeroen J Bax
    [Show abstract] [Hide abstract] ABSTRACT: BV electrical wavefront fusion can induce improvement in LV size and function during CRT. Changes in BV wave propagation sequence and duration register in the QRS complex on the standard ECG. We derived a wave interference method for characterization of BV fusion to predict LV reverse remodeling. Develop a simple ECG method for predicting reverse remodeling during CRT. QRS complexes during LBBB and CRT were analyzed in 375 patients with EF ≤ 35%, NYHA III-IV (Leiden, N=226) and EF ≤ 40%, NYHA I-II (REVERSE Trial, N=149) for predictors of ≥ 10% reduction in LVESV at 6 months. CRT-induced changes in ventricular activation (QRS fusion contour) and electrical asynchrony (QRS difference = BV-paced QRS - LBBB QRS, milliseconds), and LBBB substrate (LV activation time, QRS score for LV scar) were quantified. Multivariable predictors of reverse remodeling were (1) Either of 2 BV fusion patterns: QRS normalization in leads V1-V2 (N=66, 18%), 3.71 [1.26, 10.94] or New/increased R wave in V1-V2 (N=267, 71%), 1.55 [0.65, 3.65], (2) QRS difference ≤ -25, 2.35 [1.12, 4.91], (3) Good substrate (low-moderate QRS score, LV activation time ≥ 110 milliseconds) 2.94 [1.68, 5.14]. Remodeling rates were 40% for poor substrate and persistent LBBB QRS complex (absent BV fusion, QRS Type 3: N=42, 11%) to 97% for best BV QRS fusion pattern and greater reduction in electrical asynchrony (larger QRS difference). Easily determined QRS complex attributes before and after CRT predict LV remodeling.
    Article · Jan 2014 · Heart rhythm: the official journal of the Heart Rhythm Society
  • Michael O Sweeney
    Article · Aug 2013 · Journal of Cardiovascular Electrophysiology
  • Andrew E Epstein · John P Dimarco · Kenneth A Ellenbogen · [...] · Michael O Sweeney
    Article · Dec 2012 · Circulation
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    Full-text available · Article · Dec 2012 · The Journal of thoracic and cardiovascular surgery
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    [Show abstract] [Hide abstract] ABSTRACT: Management strategies for ventricular arrhythmias are guided by the risk of sudden death and severity of symptoms. Patients with a substantial risk of sudden death usually need an implantable cardioverter defibrillator (ICD). Although ICDs effectively end most episodes of ventricular tachycardia or ventricular fibrillation and decrease mortality in specific populations of patients, they have inherent risks and limitations. Generally, antiarrhythmic drugs do not provide sufficient protection from sudden death, but do have a role in reducing arrhythmias that cause symptoms. Catheter ablation is likewise important for reducing the frequency of spontaneous arrhythmias and is curative for some patients, usually those with idiopathic arrhythmias and no heart disease. Arrhythmia surgery is now infrequent, offered by only a few specialised centres for refractory arrhythmias. Advances in understanding of genetic arrhythmia syndromes and in technology for mapping and ablation of ventricular arrhythmias, and enhanced algorithms in implantable devices for rhythm management, have contributed to improved outcomes.
    Full-text available · Article · Oct 2012 · The Lancet
  • Michael O Sweeney
    Article · Sep 2012 · Heart rhythm: the official journal of the Heart Rhythm Society
  • Michael O Sweeney
    Article · Jul 2012 · Circulation
  • Michael O Sweeney · Scott Sakaguchi · Grant Simons · [...] · Fang Yang
    [Show abstract] [Hide abstract] ABSTRACT: The Center for Medicare & Medicaid Services expanded coverage for primary prevention (PP) implantable cardioverter-defibrillators (ICDs) included a request for outcome comparisons between 3 Group B subgroup patients (left ventricular ejection fraction [LVEF] 31%-35%, nonischemic dilated cardiomyopathy [NDCM] duration of <9 months, and New York Heart Association class IV heart failure (HF) treated with cardiac resynchronization therapy/defibrillator [CRT/D]) and non-Group B patients (LVEF ≤30%, NDCM duration of ≥9 months, and New York Heart Association class III HF treated with CRT/D) using real-world observational studies. To compare outcomes in Center for Medicare & Medicaid Services Group B and non-Group B PP ICD patients. OMNI was a 4-year prospective observational study that enrolled 1464 PP ICD patients with a mean LVEF of 25%; 72% were men, 78% had class II-IV HF, and 66% had coronary disease. A total of 795 (54.3%) received ICDs, and 669 (45.7%) received CRT/Ds. Ventricular tachyarrhythmia therapy rates and mortality were compared over 39 ± 18.4 months. Twenty-five percent received ventricular tachyarrhythmia therapies, and 21.2% died within 4 years. Patient-year therapy rates were not significantly different for LVEF of 31%-35% (0.36 per year) vs ≤30% (0.51/y) and CRT/D for class IV HF (0.21/y) vs class III HF (0.43 per year) but were lower for NDCM <9 months (0.3/y) vs ≥9 months (0.85/y; P = .02). Four-year mortality was similar for LVEF 30%-35% (22.6%) vs <30% (24.4%) and NDCM <9 months (14.2%) vs ≥9 months (12.3%) but was higher for CRT/D for class IV HF (48.6%) vs class III HF (27.4%) (P = .01). Patient-year ventricular tachyarrhythmia therapy rates did not differ between non-Group B and Group B PP ICD patients, though NDCM <9 months was significantly lower. Survival at 4 years was lowest in patients with New York Heart Association class IV HF treated with CRT/D and similar between all other non-Group B and Group B patients.
    Article · Feb 2012 · Heart rhythm: the official journal of the Heart Rhythm Society
  • Michael O Sweeney
    Article · Nov 2011 · Heart rhythm: the official journal of the Heart Rhythm Society
  • Michael O Sweeney
    Article · Nov 2011 · Heart rhythm: the official journal of the Heart Rhythm Society
  • Article · Aug 2011 · Journal of Cardiac Failure
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    Joachim Seegers · Markus Zabel · Michael O Sweeney · Dirk Vollmann
    [Show abstract] [Hide abstract] ABSTRACT: ICD, oversensing, conduction block Case Report A 94-year-old man with ischemic cardiomy-opathy, permanent atrial fibrillation, and recurrent symptomatic ventricular tachycardia (VT) presented after a brief syncopal spell to defibrillator (ICD). The device was connected to a Model 0145 (Guidant, Natick, MA, USA) right ventricular (RV) integrated bipolar ICD lead, implanted with the initial ICD system for secondary prevention of sudden cardiac death in 1999. Upon device interrogation, all lead values were within normal ranges (RV pacing threshold: 1.0 V/0.5 ms, R-wave amplitude sensing: 8.3 mV, pacing impedance: 642 ohm). Three tachycardia detection zones had been programmed (VT1 ≥ 140 beats per minute [bpm], 26 cycles; VT2 ≥ 182 bpm, 20 cycles, ventricular fibrillation [VF] ≥ 231 bpm, 12 of 16), and the stability criterion (±24 ms) was programmed on for the VT detection zones. Antibradycardia stimulation was programmed to rate-adaptive, single-chamber RV pacing (VVI-R mode) between 75 and 120 bpm. The episode counter indicated that two tachycardia episodes had been detected within a 1-minute time interval. The first episode in the VT1 zone was classified as supraventricular tachycardia, and the second episode in the VT2 zone was classified as VT Financial support: None.
    Full-text available · Article · Apr 2011 · Pacing and Clinical Electrophysiology
  • Michael O Sweeney
    Article · Mar 2011 · Heart rhythm: the official journal of the Heart Rhythm Society
  • Michael O Sweeney
    Article · Dec 2010 · Circulation
  • Michael O Sweeney · Kenneth A Ellenbogen · Anthony S.L. Tang · [...] · Todd Sheldon
    [Show abstract] [Hide abstract] ABSTRACT: The need for pacing support in typical ICD patients is unknown. This study sought to determine whether atrial pacing with ventricular backup pacing is equivalent to ventricular backup pacing only in implantable cardioverter-defibrillator (ICD) patients. We randomized 1,030 patients from 84 sites with indications for ICDs, with sinus rhythm, and without symptomatic bradycardia to atrial pacing with ventricular backup at 60 beats/min (518) or ventricular backup pacing at 40 beats/min (512). The primary end points were time to death, heart failure hospitalization (HFH), and heart failure-related urgent care (HFUC). Follow-up was 2.4 ± 0.8 years when the trial was stopped for futility. There were 355 end point events (103 deaths, 252 HFH/HFUC) in 194 patients favoring ventricular backup pacing (event-free rate 77.7% vs. 80.3% for atrial pacing at 30 months; hazard ratio 1.14, upper confidence bound 1.59, prespecified noninferiority threshold 1.21), therefore equivalence between pacing arms was not demonstrated. Overall HFH/HFUC rates were slightly higher during atrial pacing (event-free rate 85.4% vs. 86.4% for ventricular backup pacing). Exploratory analyses revealed that the difference in HFH/HFUC rates was largely seen in patients with a PR interval ≥230 ms. There were no differences between groups for atrial fibrillation, ventricular tachycardia/ventricular fibrillation, quality of life, or echocardiographic measurements. Fewer patients in the atrial pacing group were reported to develop an indication for bradycardia pacing (3.7% vs. 7.3%, P = .0053). Equivalence between atrial pacing and ventricular backup pacing only could not be demonstrated. CLINICAL TRIALS IDENTIFIER: NCT00281099.
    Article · Nov 2010 · Heart rhythm: the official journal of the Heart Rhythm Society
  • Michael O Sweeney
    Article · Nov 2010 · Journal of Cardiovascular Electrophysiology
  • Michael O Sweeney · Lou Sherfesee · Paul J DeGroot · [...] · Bruce L Wilkoff
    [Show abstract] [Hide abstract] ABSTRACT: Implantable cardioverter-defibrillator (ICD) shocks have been associated with an increased risk of death. It is unknown whether this is due to the ventricular arrhythmia (VA) or shocks and whether antitachycardia pacing (ATP) termination can reduce this risk. The purpose of this study was to determine whether mortality in ICD patients is influenced by the type of therapy (shocks of ATP) delivered. Cox models evaluated effects of baseline characteristics, ventricular tachycardia (VT; <188 bpm), fast VT (FVT; 188-250 bpm), ventricular fibrillation (VF; >250 bpm), and therapy type (shocks or ATP) on mortality among 2135 patients in four trials of ATP to reduce shocks. Over 10.8 +/- 3.3 months, 24.3% patients received appropriate shocks (50.6%) or ATP only (49.4%), and 6.6% died. Mortality predictors were age (hazard ratio 1.07, 95% confidence interval 1.04-1.08, P <.0001), New York Heart Association class III/IV (3.50 [2.27-5.41]; P <.0001), coronary disease (3.08 [1.31-7.25]; P = .01), and cumulative VA (VT + FVT + VF) episodes shocked (1.20 [1.13, 1.29]; P <.0001). Beta-blockers (0.65, 0.46-0.92; P <.0001) and remote myocardial infarction (0.53, [0.38-0.76] P = .0004) predicted reduced risk. Since 92% of VT and all VF received a single therapy type (ATP and shocks, respectively), the effect of therapy on episode risk could not be established. For FVT (32% shocked, 68% ATP), episode and therapy effects could be uncoupled; ATP-terminated FVT did not increase episode mortality risk, whereas shocked FVT increased risk by 32%. Survival rates were highest among patients with no VA (93.8%) of ATP-only (94.7%) and lowest for shocked patients (88.4%). Monthly episode rates were 80% higher among shocked versus ATP-only patients. Shocked VA episodes are associated with increased mortality risk. Shocked patients have substantially higher VA episode burden and poorer survival compared with ATP-only-treated patients.
    Article · Mar 2010 · Heart rhythm: the official journal of the Heart Rhythm Society
  • Michael O Sweeney · Rutger J van Bommel · Martin J Schalij · [...] · Jeroen J Bax
    [Show abstract] [Hide abstract] ABSTRACT: Cardiac resynchronization therapy for heart failure with left bundle branch block reduces left ventricular (LV) conduction delay, contraction asynchrony, and LV end-systolic volume ("reverse remodeling"). Up to one third of patients do not improve, and the electric requirements for reverse remodeling are unclear. We hypothesized that reverse remodeling is predicted by the left bundle branch block ventricular activation sequence, the paced activation sequence, and interactions between these 2 conditions. Twelve-lead ECGs during left bundle branch block and cardiac resynchronization therapy were analyzed in 202 consecutive patients (New York Heart Association class III to IV heart failure, ejection fraction < or =35%) for predictors of reverse remodeling (> or =10% reduction in end-systolic volume) at 6 months. Greater longest baseline LV activation time predicted increased odds of reverse remodeling (odds ratio [confidence interval]=1.30 [1.11, 1.52] per 10-ms increase), whereas higher QRS scores for LV scar predicted reduced reverse remodeling (odds ratio [confidence interval]=0.49 [0.27, 0.88] for each 1-point increase from 0 to 4; 0.92 [0.83, 1.01] for each 1-point increase >4). After cardiac resynchronization therapy, increasing R amplitudes in leads V(1) through V(2) (odds ratio [confidence interval]=2.76 [1.01, 7.51] for each 1x increase over [baseline Rx4.5]) and left-->right frontal axis shift (odds ratio [confidence interval]=2.00 [0.99, 4.02]), indicators of ventricular activation wavefront fusion, were positive predictors of reverse remodeling. Predicted probability of reverse remodeling ranged from <20% for patients with adverse predictors to 99% for those with positive predictors. Ventricular activation with the use of the ECG accurately predicts LV reverse remodeling during cardiac resynchronization therapy. Greater longest baseline LV activation time and smaller scar volume combined with wavefront fusion on the paced ECG, anticipate higher probability of reverse remodeling.
    Article · Feb 2010 · Circulation
  • Michael O Sweeney
    Article · Nov 2009 · Europace

Publication Stats

9k Citations


  • 2005-2015
    • Harvard University
      Cambridge, Massachusetts, United States
    • American Heart Association
      Dallas, Texas, United States
  • 2011
    • University of Rochester
      • Division of Cardiology
      Rochester, New York, United States
  • 1997-2009
    • Brigham and Women's Hospital
      • Cardiac Arrhythmia Service
      Boston, Massachusetts, United States
  • 2003-2006
    • Duke University
      Durham, North Carolina, United States