Benefits of Intra Aortic Balloon Pump (IABP) in Acute Coronary Syndrome

Rupesh George,a  Biju Jacob,b  T P Antony,b Regi Jose,c  Jayaraj Kb

a. Cardiac Centre, Amala Institute of Medical Sciences; b. Department  of General Medicine, Amala Institute of Medical Sciences; c. Department of Community Medicine, Gokulam Medical College, Trivandrum, Kerala

Abstract

IABP (Intra Aortic Balloon Pump) is a device which improves diastolic coronary and systemic flow  and reduces  afterload  and myocardial work.  ACC/AHA guidelines list IABP therapy in cardiogenic shock as Class 1b recommendation. European society also recommends the same.

Recent studies published in European Heart Journal has raised doubts about the outcome, clinical efficacy, and therapeutic benefits of IABP2.  We conducted a record based descriptive study on the in hospital outcome (death or survival) of 72 patients who underwent emergency IABP insertion for Acute coronary syndrome (ACS).  Data was collected from medical records using a structured questionnaire.

It was observed that 62.5% of patients survived with IABP. Its use was observed mostly in Anterior wall MI followed by Inferior wall MI & NSTEMI.  Survival rates were significantly more for multi vessel than single vessel disease (p value- 0.02).  Comparison of each indication for insertion was done with the  overall survival rate.  In Cardiogenic shock , survival rates were low even with IABP support (57.8% vs 62.5 %), but statistically significant increase in survival rates  were observed in cases of Arrhythmia (91.6%  vs 62.5% p value-0.02)  and Inferior wall MI (92.6%vs 62.5% p value- 0.024).

Keywords: ,

Introduction

Unstable Angina Pectoris (UA) or acute myocardial infarction (AMI) which constitute Acute Coronary Syndrome (ACS) is one of the main killers in the developing and developed world.  The main tools to determine the likelihood of ACS are the symptom history, the ECG  and  blood markers of myocardial injury such  as  troponin T (TnT).11   Mortality data  from Global Burden of  Diseases studies have revealed that cardiovascular diseases especially coronary heart disease are important causes of death in India.  Worldwide, of the 17.5 million deaths from cardiovascular diseases, 20% deaths occurred in high income countries, 8% in upper-middle income countries, 37% in lower-middle income countries and 35% in low income countries including India.12

 IABP (Intra Aortic Balloon Pump)  was  introduced  in 1968  by Dr Adrian Kantrowitz  to improve diastolic coronary and systemic blood flow, and reduce  afterload  and  myocardial work.5  It  is  an inflatable 32-40 cc balloon, triggered  to  inflate  with  helium  immediately  after  aortic valve closure  at  dicrotic  notch  and  triggered  to  deflate  with  isovolumetric contraction.

The  benefits of  Inflation  include  increased  coronary blood flow, increased diastolic pressure, increased systemic perfusion  and  potential for increased  coronary  collateral  circulation.

Benefits of  deflation  include  decreased  afterload,  shortened  isovolumetric phase, increased stroke volume and enhanced forward cardiac output.3  IABP is suggested  to  act  as a  stabilizing  measure or  to  prevent  catheterization  laboratory events.8,9  The SHOCK trial, (Should we emergently revascularize Occluded Coronaries in cardiogenic shocK), in 1999 – supported the  use of IABP for initial stabilisation in Cardiogenic shock.1

ACC/AHA  supports  IABP therapy in  Cardiogenic shock as Class 1b recommendation. Recent study  conducted  by  Krischan etal ( Eur heart journal), in 2009,  raised  doubts  regarding  the efficacy of  IABP  in  STEMI  &  LV dysfunction.2

Objectives

  1. To compare  survival rates for various indications of IABP insertion
  2. To study factors that determine survival in IABP insertion 

Materials and Methods

Clinical records of all patients irrespective of age, gender, and co-morbidities who presented to the Emergency department of Amala Institute with Acute coronary syndrome and in whom emergency  IABP was inserted during the period from 1/8/2011 -1/8/2013 were analysed.  A total of 72 patients were studied.

The data was analysed using the standard statistical technique of Student ‘t’ test for interval data and chi square for nominal data.

Indications for IABP Insertion include:

  1. Cardiogenic shock – Persistent hypotension despite adequate filling pressures.
  2. Slow fill of the Coronaries which occurs during or after the coronary angiogram/angioplasty
  3. Critical lesion:  in  high grade stenosis or multivessel involvement
  4. Mechanical defects including Ventricular septal defects, Mitral regurgitation, Ventricular rupture
  5. Arrhythmia refractory to medical treatment 

Results

Table 1. Survival Rates in different Acute Coronary Syndromes (ACS)

Table 1. Survival Rates in different Acute Coronary Syndromes (ACS)

Out of 72 patients, 45 survived (62.5%) with IABP.  Maximum  survival rate was seen in the age group of <60 yrs.  Survival rate was reduced after the age of 60 yrs. Majority patients were males (p value – 0.4).  64.9% of males and 53.3% of females survived. Survival rate in females was less when compared to males. Majority of patients had multi-vessel disease. Survival rates were better in multi-vessel disease than single vessel involvement ( p value-0.020).  Survival rate with LT MAIN vessel involvement is low even with IABP support (p value- 0.019).  Survival rates were maximum for IWMI followed by AWMI.  Mortality rate was highest for  NSTEMI  ( p value-0.024) (Table 1).

Table 2. Comparison of Various Indications for IABP Insertion

Table 2. Comparison of Various Indications for IABP Insertion

Mortality rate with IABP in patients with shock is 42.2%  (p value-0.39). In case of arrhythmia, the survival rate with IABP was 91.6 %  when compared with overall survival rate of 56.6% (p value-0.02).

Survival rate was 76.9% in cases of slow flow when compared to 59.3% overall survival rate with IABP (p value-0.23). Survival rate was 66.6% in cases of critical lesion when compared to 61.6% overall survival rate with IABP (p value-0.7) (Table 2).

Discussion

IABP insertion can increase survival rate in Acute Coronary Syndrome.  The survival rate was more in males and in those less than 60 yrs.  IABP had statistically significant better outcome with multi vessel than single vessel involvement.  This could be due to the ischemic preconditioning in multi vessel involvement, ie  myocardium will be exposed  to slow  ischemia  for long time in case of multivessel disease, and will adapt better than single vessel disease.

There was no significant difference in survival rate in terms of gender (64.9% of males and 53.3% of females survived).  It was also seen that even though men had a higher incidence of Acute coronary syndrome, their survival was better than females. This could be due to their better ability to withstand stress.

Left main vessel involvement had statistically significant low survival rate even with IABP.  This could be because of the extensive area of   infarct involving the left ventricle which is supplied by the vessel.10

Mortality rate after IABP insertion in patients with Cardiogenic shock was  42.2%  and survival rate 57.8%.  This was comparable to the SHOCK trial mortality rate of 46.7% ( in the early revascularization  group).  Similar study conducted by  Abdul Waheb  etal  supported IABP use before angioplasty in Myocardial infarction with Cardiogenic shock.4

The maximum survival rates were seen in IWMI, Arrhythmia & Multi vessel disease.  The highest survival rate was seen with IWMI followed by AWMI (statistically significant).  NSTEMI had high mortality rate even with IABP support.  IABP was found to significantly increase survival rates in cases of IWMI and   refractory arrhythmias

Conclusion

IABP improves survival rates in ACS.  Maximum survival rates were seen  in  IWMI, Arrhythmia & Multi vessel disease.  Mortality rates are still high in ACS even with IABP insertion, hence research should be done in developing other mechanical devices and management  protocols  that will further improve the survival rate.

Limitations of this study are its small sample size, lack of comparison to a group without IABP and its predominant male sample.

References

  1. Judith S Hochman etal, Early Revascularization in Acute Myocardial Infarction Complicated by Cardiogenic Shock(SHOCK trial), N Engl J Med 1999; 341:625-634
  2. Krischan etal, A systematic review and meta analysis of IABP therapy in STEMI –Should we change guidelines? Eur Heart journal (2009)30, pg 459-468
  3. Topol & Griffin, Manual of cardiovascular medicine, 3rd edition, pg 776-790.
  4. Abdul waheb etal.,Comparison of hospital mortality with intra-aortic balloon counter pulsation insertion before versus after primary percutaneous coronary intervention for cardiogenic shock, American journal of cardiology,2010, April 1,105(7): 967-71
  5. Kantrowitz A, Tjonneland S, Freed PS, Phillips SJ, Butner AN, Sherman JL Jr. Initial clinical experience with intraaortic balloon pumping in cardiogenic shock. JAMA 1968;203:113–118.
  6. Kern MJ, Aguirre F, Bach R, Donohue T, Siegel R, Segal J. Augmentation of coronary blood flow by intra-aortic balloon pumping in patients after coronary angioplasty. Circulation 1993;87:500–511
  7. Sjauw KD, Engstrom AE, Henriques JP. Percutaneous mechanical cardiac assist in myocardial infarction. Where are we now, where are we going? Acute Card Care 2007;9:222–230.
  8. Smalling RW, Cassidy DB, Barrett R, Lachterman B, Felli P, Amirian J. Improved regional myocardial blood flow, left ventricular unloading, and infarct salvage using an axial-flow, transvalvular left ventricular assist device. A comparison with intra-aortic balloon counterpulsation and reperfusion alone in a canine infarction model. Circulation 1992;85:1152–1159.
  9. Brodie BR, Stuckey TD, Hansen C, Muncy D. Intra-aortic balloon counterpulsation before primary percutaneous transluminal coronary angioplasty reduces catheterization laboratory events in high-risk patients with acute myocardial infarction. Am J Cardiol 1999;84:18–23.
  10. Jean fejadet etal, Current management of  Left main coronary artery disease , European heart journal, vol 33, issue 1, page 36-50
  11. Alexander etal, What decides the suspicion of acute coronary syndrome in acute chest pain patients?, BMC Emergency medicine, 14, 9
  12. Rajeev Gupta, KD Gupta  Coronary Heart Disease in Low Socioeconomic Status Subjects in India: ” An Evolving Epidemic” Indian Heart J. 2009; 61:358-367.

Author Information

  1. Rupesh  George, Consultant Cardiologist, Cardiac centre, Amala Institute of Medical Sciences
  2. Biju Jacob, PG Resident, Department  of General Medicine, Amala Institute of Medical Sciences
  3. T P Antony, MBBS, MD, MNAMS, MRCP, FRCP,  Professor and HOD, Department of General Medicine, Amala Institute of Medical Sciences
  4. Regi Josel, MBBS, DPH, MD,DNB, M Phil, Professor, Department of Community Medicine, Gokulam Medical College, Trivandrum, Kerala
  5. Jayaraj K, Assistant professor, Department of General  Medicine, Amala Institute of Medical Sciences

Abbreviations

  • IABP- Intra Aortic Balloon Pump
  • ACS- Acute Coronary Syndrome
  • NSTEMI- Non ST segment Elevation Myocardial Infarction
  • STEMI- ST segment Elevation Myocardial Infarction
  • LV- Left Ventricle
  • AWMI- Anterior Wall Myocardial Infarction
  • IWMI – Inferior Wall Myocardial Infarction
  • ACC- American college of Cardiology
  • AHA- American Heart Association

Conflicts of Interest: None declared

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