INTRAAORTIC BALLOON SUPPORT FOR MYOCARDIAL INFARCTION WITH CARDIOGENIC SHOCK Holger Thiele, Uwe Zeyer, Franz-Josef Neumann, Miroslaw Ferenc, Hans-Georg Olbrich, Jörg Hausleiter et alThe NEW ENGLAND JOURNAL of MEDICINE october 4,2012 vol.367 no.14
INTRODUCTION IABP is a mechanical device that increases myocardial oxygen perfusion while at the same time increasing cardiac output Increasing cardiac output increases coronary blood flow and therefore myocardial oxygen delivery
Consists of a cylindrical polythene balloon that sits in aorta, approximately 2cm from the left subclavian artery and counter pulsates Actively deflates in systole, increasing forward blood flow by reducing after load. It actively inflates in diastole, increasing blood flow to the coronary arteries These actions combine to decrease myocardial oxygen demand and increase myocardial oxygen supply
NEED OF THIS STUDY A meta-analysis that included only cohort studies suggested that the use of an IABP is associated with a reduction by 11% Inconclusive evidence might be one explanation for the in the risk of death. current use of IABP in only 25 to 40% of patients with In the recent shock, despite the recommendationsonly 45 cardiogenic (IABP-SHOCK) trial, which involved in the guidelines patients, no significant difference was observed with respect to the (APACHE II) score for severity of illnessThebetween patientstrial was designed to test the hypothesis that IABP-SHOCK II assigned to IABP and those assigned to aIABP as compared that received available care, although serial control group with the best standard medical therapy alone,results in natriuretic peptide levels were significantly reduced in brain a reduction in mortality among patients with acutemyocardial infarction complicated by cardiogenic shock for whom the balloon-pump group.early revascularization is planned
METHODSTYPE OF STUDY Randomized, prospective, open-label, multicenter trial, Randomization Internet-based program, with stratificationaccording to center.PERIOD-june16th,2009-march3,2012
ELIGIBLE CRITERIA Acute myocardial infarction (with or without ST segment elevation) complicated by cardiogenic shock and if early revascularization (by means of PCI or CABG) was planned.CARDIOGENIC SHOCK Systolic blood pressure <90 mm hg for more than 30 minutes Catecholamines to maintain a systolic pressure >90 mm hg Signs of pulmonary congestion and Impaired end- organ perfusion. Altered mental status Cold, Clammy skin and extremities Oliguria with urine output of less than 30 ml per hour Serum lactate level higher than 2.0 mmol per liter
EXCLUSION CRITERIA Resuscitation for more than 30 minutes Had no intrinsic heart action were in a coma with fixed dilatation of pupils that was not induced by drugs Had a mechanical cause of cardiogenic shock (e. g Ventricular septal defect or papillary muscle rupture) Had onset of shock more than 12 hours before screening Older than 90 years of age Shock as a result of a condition other than acute myocardial infarction Had severe concomitant disease associated with a life expectancy of less than 6 months
Had a massive pulmonary embolism Severe peripheral arterial disease precluding insertion of an IABP or aortic regurgitation greater than grade II in severity
OUTCOMESNO SIGNIFICANT DIFFERENCE BETWEEN TWO GROUPS
DISCUSSION No immediate improvement in blood pressure or heart rate between two groups. Although positive effect of IABP on multiorgan dysfunction at day 2 and 3, as assessed with the use of the SAPS II, this effect was not evident at day 4. No significant effects on CRP level or serum lactate level, which were assessed as measures of inflammation and tissue oxygenation.
Studies showed IABP results in a hemodynamic benefit as a result of afterload reduction and diastolic augmentation with improvement in coronary perfusion. However, the effects on cardiac output are modest and might not be sufficient to reduce mortality. In a recent, small, randomized trial, there were no significant differences in cardiac power output, left ventricular stroke- work index, or systemic vascular resistance between patients assigned to IABP and those assigned to a control group.
Use of IABP before coronary revascularization may make the revascularization procedure safer by improving left ventricular unloading. However, in the current trial, there was no mortality benefit in the subgroup of patients in whom the IABP was inserted before the start of revascularization, as compared with those in whom it was inserted after revascularization. In another recent randomized trial involving patients with large anterior infarctions but without cardiogenic shock, insertion of a balloon pump before PCI, as compared with control treatment did not reduce the infarct size.
LIMITATIONS① Blinding was not possible because of the nature of the intervention..② Hemodynamic measurements or assess laboratory inflammatory markers other than blood pressure, heart rate, and c-reactive protein levels, not done③ The slightly lower mortality in trial — approximately 40%, as compared with 42 to 48% in other randomized trials and registries — might suggest that trial included a higher percentage of patients with mild or moderately severe cardiogenic shock, a factor that could preclude generalization of the results to patients with the most severe forms of cardiogenic shock.
④ The negative overall result, cannot definitively rule out a type II error;⑤ No information about longer-term outcomes. To minimize bias, use of a central randomization system, and the members of the clinical events committee were unaware of the group assignments.
CONCLUSION CONTROLLED TRIAL OF INTRAAORTIC BALLOON PUMP S U P P O R T I N PAT I E N T S W I T H C A R D I O G E N I C S H O C K C O M P L I C AT I N G M Y O C A R D I A L I N F A R C T I O N F O R W H O M E A R LY R E VA S C U L A R I Z AT I O N A S C O M PA R E D W I T H C O N V E N T I O N A L T H E R A P Y, D I D N O T R E D U C E 3 0 - D AY M O R TA L I T Y.