Cardiology

Topic 1 - Summary
1. Citation: Victor Coba, Emanuel Rivers, et al. The incidence and significance of bacteremia in out of hospital cardiac arrest. Journal: Resuscitation. 2014. Pgs 196-202
2. Summary/Bottom Lines:
  • This study is first to report over 38% incidence of bacteremia in OHCA adults
  • Bacteremic OHCA adults had worse metabolic derangements, higher lactates, and lower ED survival vs non bacteremic OHCA adults
  • The consensus of the group was this would not change our treatment strategy in the Emergency Department
3. Methods:
  • Prospective observational convenient sampling study of OHCA patients seen at an urban academic teaching institution from Aug 2007-Aug 2009
  • Researchers obtained blood cultures near time of cardiac arrest event in patients
  • Aerobic/anaerobic blood cultures (10mL per bottle) were collected through venous/art access catheters by personnel not associated with ED treatment team
  • Bacteremia: minimum of 2 blood culture bottles with skin flora pathogens or one blood culture bottle with non-skin flora pathogen
  • Non-bacteremia: no bacterial growth after at least 5 days of intubation
  • Results:
    1. 250 OHCA patients had 2 sets of blood cultures obtained
    2. 77 (31%) met exclusion criteria
    3. Primary: Of the remaining 173 patients, 71 had positive blood cultures, of which 6 cultures were defined as contaminants (skin flora) and included for analysis in non-bacteremic OHCA group
    4. Secondary: 28 day mortality for bacteremic and non-bacteremic groups was similar (93.8% vs 92.6%)
    5. Secondary: ED survival was significantly lower in bacteremic (25%) vs non bacteremic group (40%)
4. Limits:
  • Single institution
  • Random blood cultures drawn
  • Study not powered to evaluate impact of bacteremia on survivability
  • True number of out of hospital cardiac arrest patients eligible for enrollment unknown
  • Study not designed to determine infectious causality of cardiac arrest or factors influencing ROSC
  • Blood cultures from other potential sites of infection were not drawn
  • The study has applicability to EM practice, however as a group, the consensus was that this would not change our overall management of a septic appearing patient.
5. Additional Info: There's also a great discussion about this on the July 2014 EMRAP episode.
6. Author: Dr. Raymond Ruiz & Dr. Brett Trullender

 

Topic 2 - Summary
1. Citation: Cai Q, Mehta N, Sgarbossa EB, et al. The left bundle-branch block puzzle in the 2013 ST-elevation myocardial infarction guideline: from falsely declaring emergency to denying reperfusion in a high-risk population. Are the Sgarbossa Criteria ready for prime time?. Am Heart J. 2013;166(3):409-13.
2. Summary/Bottom Lines: The 2004 STEMI guidelines recommended reperfusion therapy for patients with suspected ACS and a new left bundle branch block. According to the authors, this policy resulted in too may patients receiving some kind of reperfusion therapy (PCI or fibrinolytic) when no full thickness infarct was present. The new 2013 guidelines no longer consider new LBBB as a STEMI equivalent, but is is clear that chest pain patients with LBBB are still very high risk (just somewhat lower risk that an obvious STEMI). Some method is required to identify the higher risk patients in the LBBB group. In light of the new recommendations about LBBB, the Sgarbossa criteria can provide a high specificity (upwards of 98% for score >3) but weak sensitivity ( around 20%). Overall ,the positive predictive value of Sgarbossa criteria are useful. Inclusion of the ST/S ratio in a modified Sgarbossa criteria can improve the sensitivity to 91%, thus providing an effective way to identify very high risk chest pain patients with left bundle branch block .  Bedside echo can also play an important role in evaluating patients with wall motion abnormality or hypokinesia who would be more likely to benefit from emergent reperfusion therapy.
3. Methods: This paper is essentially a systematic review of several rather large fibrinolytic trials. When combined, these early trials look at thousands of individuals and are very well powered, which is why they were also used to justify the STEMI guidelines.
4. Limits: There is no ostensible bias that I could identify. It does seem like the authors were interested in elucidating the dangers of using LBBB without Sgarbossa criteria (those dangers being inappropriate reperfusion therapy). It is clear the chest pain patients with LBBB have a very high risk, but there is no mention of risk/benefit analysis in patients with new LBBB. What is the actual risk vs benefit of getting PCI if there is a new LBBB without consideration of Sgarbossa? The authors recommendations seem to provide a sharper focus when looking at chest pain patients with LBBB, but will obviously result in less interventions if followed.  In the end, a person with LBBB that has chest pain has a high one-year mortality, but these guidelines would keep many of them out of the cath lab.
5. Additional Info:  
6. Author: Dr. Jonathan Tull

 

Topic 1 - Summary
1. Citation: McAlister F, Ezekowitz J, Wiebe N, et al.  Cardiac Resynchronization Therapy for Congestive Heart Failure-Summary.  Agency for Healthcare Research and Quality.  Evidence Report/Technology Assessment Number 106, Nov. 2004.
2. Summary/Bottom Lines:
  • In adult patients with symptomatic heart failure, is CRT more effective than optimal medical care alone?  24% relative reduction in all-cause mortality and a 35% reduction in heart failure hospitalizations in patients with reduced ejection fractions.
  • Is the implantation of CRT system safe for patients?
         Appears to be in the hands of experienced clinicians;
         limited data on safety in the hands of clinicians with
         limited training.
  • What is the role of CRT in the treatment of heart failure?  CRT should absolutely join the list of efficacious treatment modalities for CHF, but we are still lacking long-term data.
  • What is the cost-effectiveness of CRT in patients with congestive heart failure? No question it is more expensive than medical treatment alone. As mentioned before, long-term data still needs to be collected. Study reports probability that CRT is cost effective is less than 59%, given a max of $100,000 per quality adjusted life year.
3. Methods:
  • Large systematic review
  • Two investigators independently screened titles and abstracts.  Two additional investigators independently assessed full test.  Disagreements resolved via 3rd party adjudication.
  • Markov decision model constructed to perform decision analysis.
  • Literature search revealed 9 trials reporting on efficacy of CRT and another 17 trials reporting on safety of CRT.
  • Results
    • CRT reduces all cause mortality by 25%.
    • No difference in cardiac mortality.
    • No difference in non cardiac mortality.
    • CRT reduces heart failure hospitalizations by 32%.
    • CRT improves 6-minute walk test.
    • CRT improves NYHA class by 23%.
    • CRT improves quality of life using Minnesota Living With Heart Failure Questionnaire.
    • CRT improves peak oxygen consumption.
    • Peri implantation risks:  0.4% death rate during implantation.  90% success rate.
    • Post implantation risks: 7% mechanical malfunction, 9% lead dislodgement, 1.4% infection rate, 2% arrhythmia.
    • CRT results in median gain life expectancy but at increased cost.
4. Limits:
  • Several assumptions made to conduct decision analysis, but decision analysis model requires that assumptions be made
  • Randomization occurred after implantation of CRT device, which can affect generalizability of outcomes.
  • Studies did not account for any comorbidities.
  • Trials only included experienced clinicians, so there is limited data on safety of implantation
  • Lack of long term follow up, therefore hard to evaluate cost effectiveness
  • Data derived from several sources, which may have led to confounding data.
5. Additional Info:
  1. Dr. Mackay pointed out that it was odd to see an improvement in all cause mortality, but not cardiac or non-cardiac mortality.
  2. Dr. Nelson discussed in depth the process in which the health-related quality of life of patients with heart failure is estimated.  Basically a sample of people over the age of 40 WITHOUT cardiac disease estimated utilities for standardized health state descriptions using the “gamble” technique.  From this data, the quality-adjusted life year of $100,00 was obtained.
  3. We also discussed how cost effectiveness depends on perspective.  From society’s perspective, CRT may not be viewed as cost effective due to taxpayers ultimately bearing the cost.  However, from a patient’s perspective, CRT may be viewed as cost effective.
6. Author: Dr. Marshall Baca

 

Topic 2 - Summary
1. Citation: Wailoo, Allan. (June 8, 2009). Primary angioplasty versus thrombolysis for acute ST-elevation myocardial infarction: an economic analysis of the National Infarct Angioplasty project. Heart 2010 96: 668-672
2. Summary/Bottom Lines: This economic study from the UK shows that PCI is more cost-effective than thrombolysis in acute STEMI patients; especially when the patient’s call to balloon time is minimized. Patients should not be transferred from another facility, and arguably ambulances should bypass non-angioplasty centers. Because of the delay in treatment, patients that require transfer to a PCI-capable facility should have thrombolytics administered instead.
3. Methods: Assuming 20k pounds per QALY (quality-adjusted life years) threshold, the outcome was that PCI is more cost-effective with a probability of 90%. . The sensitivity analysis, essentially breaking down the study into different subgroups, showed that it was even more cost-effective for those patients admitted directly to the catheter lab rather than another hospital department or transfer. The probability was more than 95% if patients were directly admitted to the cardiac catheter lab, 75% if admitted via ED or Coronary care unit, and 38% if transferred to angioplasty center from another hospital.  The term “dominated” is used for the transferred patients because their treatment is not considered cost-effective.
4. Limits: If widespread use of pre-hospital thrombolysis reduced call to needle times in thrombolysis-based practice, then the potential effectiveness and cost-effectiveness of PCI would be reduced. Another study mentioned, CAPTIM (Comparison of Primary Angioplasty and pre-hospital fibrinolysis in acute myocardial infarction) shows that those presenting in the first 2 hours of appearance of symptoms who were treated with pre-hospital thrombolysis seemed to have better outcomes than those taken directly for primary PCI.
5. Additional Info:
  • No economic study will ever truly have the “actual cost” even if they claim so.
  • The metric used to measure the effectiveness in this study was QALY.
    1. QALY is subjective. Everyone has different definitions and value of quality when its concerning their life.
6. Author: Dr. Rahul Sachdeva