Intra-aortic balloon pump trials: questions, answers, and unresolved issues

Outcome analysis for prediction of intraaortic balloon pump support failure and long-term survival in high-risk patients undergoing mitral valve surgery

The outcome predictors of intra-aortic balloon pump (IABP) in patients who undergo mitral valve surgery remain unknown. This study aimed to retrospectively review valvular surgery in patients who received an IABP to identify the predictors of failure of IABP support and anticipate the necessary therapy. This retrospective observational study recruited a total of 157 consecutive patients who underwent open-heart mitral valve surgery with IABP implantation intraoperatively or postoperatively. Univariate and multivariate logistic regression analyses were performed to identify the risk factors attributed to 30-day mortality. Follow-up data of survivors were collected to investigate the effect of IABP support to evaluate long-term outcomes. The overall 30-day mortality was 35.7% (56 patients). The following factors that contributed to 30-day mortality included sepsis (P < .001, OR: 5.627, 95%CI: 2.422-11.683); IABP implantation postoperatively rather than intraoperatively (P = .001, OR: 6.395, 95%CI: 2.085-19.511); right heart failure (P = .042, OR: 3.419, 95%CI: 1.225-12.257); and lack of subvalvular apparatus preservation (P = .033, OR: 3.710, 95%CI: 1.094-13.167). Furthermore, follow-up data of these patients showed an estimation of 5-year and 10-year survival rates of 58.9% and 35.7%, respectively. Patients with intraoperative IABP demonstrated better long-term survival outcomes when compared to those with postoperative IABP (χ²  = 4.291, P = .038). In summary, this study distinguished the preoperative predictors of 30-day mortality of IABP-support in mitral valve surgery patients. These results indicated that early intervention with IABP should be taken into consideration in case of hemodynamic instability in critically ill patients undergoing mitral valve surgery.

Intra-aortic balloon pump counterpulsation in extensive myocardial infarction with persistent ischemia: The SEMPER FI pilot study

OBJECTIVES

This study aimed to prospectively investigate intra-aortic balloon pump counterpulsation (IABP) support in large myocardial infarction complicated by persistent ischemia after primary percutaneous coronary intervention (PCI).

BACKGROUND

Use of IABP is suggested to be effective by increasing diastolic aortic pressure, thereby improving coronary blood flow. This can only be expected with exhausted coronary autoregulation, typical in acute myocardial infarction complicated by persistent ischemia. In this situation, augmented diastolic pressure is expected to increase myocardial oxygenation.

METHODS

One hundred patients with large STEMI complicated by persistent ischemia after primary PCI were randomized to treatment with or without IABP therapy on top of standard care. IABP support was initiated following primary PCI, immediately after inclusion. Primary end point was all-cause mortality, need for (additional) mechanical hemodynamic support, or readmission for heart failure within 6 months.

RESULTS

Mean age was 63 ± 10 years, 76% were male. Mean systolic and diastolic blood pressure were 120 ± 25 mmHg and 73 ± 17 mmHg. Mean heart rate was 75 ± 18 mmHg. Before PCI, mean summed ST-deviation was 21 ± 8 mm with only minimal ST-resolution after PCI. One patient in the IABP group reached the primary end point versus four patients in the control group (2% vs. 8%; p = 0.16). After primary PCI, resolution of ST-deviation was significantly more pronounced in the IABP group (73 ± 17%) compared to the control group (56 ± 26%; p < 0.01).

CONCLUSIONS

In this pilot study, in patients with large STEMI and persistent ischemia after primary PCI, use of IABP showed a nonsignificant decrease in mortality, necessity for (additional) mechanical hemodynamic support or readmission for heart failure at 6 months, and resulted in more rapid ST-resolution.

Usefulness of Intra-aortic Balloon Pump Counterpulsation

Intra-aortic balloon pump (IABP) counterpulsation is the most widely used mechanical circulatory support device because of its ease of use, low complication rate, and fast manner of insertion. Its benefit is still subject of debate, and a considerable gap exists between guidelines and clinical practice. Retrospective nonrandomized studies and animal experiments show benefits of IABP therapy. However, recent large randomized trials do not show benefit of IABP therapy, which has led to a downgrading in the guidelines. In our view, this dichotomy between trials and practice might be the result of insufficient understanding of the prerequisites needed for effective IABP therapy, that is, exhausted autoregulation, and of not including the right patient population in trials. The population included in recent large randomized trials has been heterogeneous, also including patients in whom benefit of IABP could not be expected. The clinical condition in which most benefit is expected, that is persistent ischemia in acute ST-elevation myocardial infarction, is discussed in this review. In conclusion, this review aims to explain the physiological principles needed for effective IABP therapy, to reflect critically on the large randomized trials, and to solve some of the controversies in this field.

Predictors of mortality in patients with cardiogenic shock treated with primary percutaneous coronary intervention and intra-aortic balloon counterpulsation

BACKGROUND

Cardiogenic shock remains the most serious complication of patients hospitalized with acute myocardial infarction (AMI). Early revascularization is the cornerstone of invasive therapy, while mechanical support with intra-aortic balloon pump (IABP) is debatable. From our institutional shock registry we sought to determine predictors of in-hospital mortality-including the aspect of IABP timing-and to develop a clinical risk score for shock patients with AMI.

METHODS

From January 2005 till December 2010, 102 patients with cardiogenic shock due to AMI treated with primary percutaneous coronary intervention (PCI) and IABP were analyzed. Univariate and multivariate logistic regression analyses were used to identify independent predictors of in-hospital mortality. Logistic regression analysis and receiver-operating curves were used to generate a mortality risk score.

RESULTS

The mean age of the cohort was 70.1 ± 11.0 years and 70 % were men. One third of patients had a non-ST segment elevation myocardial infarction and 30 % had to be resuscitated before coronary intervention. Mean left ventricular ejection fraction was 25 %. After admission, 23 % of patients developed an acute renal failure and 10 % needed renal dialysis during hospital stay. In 52 % of patients IABP therapy was initiated after primary PCI, while the remaining patients had an IABP-assisted primary PCI. All-cause in-hospital mortality was 40.2 %. Using multivariate analysis, age (odds ratio [OR] 1.08, p = 0.006), resuscitation before PCI (OR 3.46, p = 0.045), vasopressor use (OR 7.88, p = 0.003), acute renal failure (OR 11.18, p = 0.001), and IABP implantation after PCI (OR 4.36, p = 0.011) were independently associated with in-hospital mortality. Based on these predictors, a mortality-risk score was calculated as follows: 1.5 × IABP timing before PCI + 0.1 × age + resuscitation before PCI + 2 × vasopressor use + 2.5 × acute renal failure. Using a cut-off value of 10.4, this score had a specificity of 83 % and a sensitivity of 82 % for prediction of in-hospital death.

CONCLUSIONS

We identified age, vasopressor use, resuscitation before PCI, acute renal failure and IABP implantation after PCI as independent predictors of in-hospital mortality in patients with cardiogenic shock due to AMI. The timing of IABP insertion was the only modifiable factor predicting in-hospital mortality in our cohort. Consequently, balloon pumping should be started before PCI to improve outcome of cardiogenic shock patients.

Contemporary cardiovascular device clinical trials (trends and patterns 2001 to 2012)

Device uptake and development have progressed over the last decade, but few quantitative data exist examining the overall operating characteristics and temporal trends of these clinical trials. We performed a systematic analysis of all cardiovascular device clinical trials from 2001 to 2012 published in medical and cardiovascular journals with the 8 highest impact factors. Of the 1,224 identified cardiovascular clinical trials, 299 (24.4%) focused specifically on devices. Each trial included a median of 335 patients (162 to 745) recruited from a median of 14 sites (3 to 38) over a median enrollment duration of 1.9 years (1.2 to 3.3). Median enrollment rate was 1.1 patients/site/month (0.5 to 4.2). Most device trials targeted coronary artery disease (55.2%), followed by arrhythmias (17.4%). Most were industry sponsored (53.6%) and included mortality as a primary end point (69.6%). The median number of patients (225 to 499, p <0.001 for trend) and enrolling sites (11 to 19, p = 0.07 for trend) increased from 2001 to 2012. During the study period, multinational enrollment grew and approached 50% (p = 0.03), whereas trials enrolling in North America exclusively decreased from 30% to 17% (p = 0.10 for trend). Approximately 70% of device trials met their primary end points; this rate did not significantly change over time. In conclusion, this descriptive study of the contemporary cardiovascular device clinical trials highlights recent trends toward larger, more international trial programs. These aggregate data may help inform future cardiovascular device development.

Effects of intra-aortic balloon pump counterpulsation on left ventricular mechanoenergetics in a porcine model of acute ischemic heart failure

We investigated the effects of intra-aortic balloon pump (IABP) counterpulsation on left ventricular (LV) contractility, relaxation, and energy consumption and probed the underlying physiologic mechanisms in 12 farm pigs, using an ischemia-reperfusion model of acute heart failure. During both ischemia and reperfusion, IABP support unloaded the LV, decreased LV energy consumption (pressure-volume area, stroke work), and concurrently improved LV mechanical performance (ejection fraction, stroke volume, cardiac output). During reperfusion exclusively, IABP also improved LV relaxation (tau) and contractility (Emax, PRSW). The beneficial effects of IABP support on LV relaxation and contractility correlated with IABP-induced augmentation of coronary blood flow. In conclusion, we find that during both ischemia and reperfusion, IABP support optimizes LV energetic performance (decreases energy consumption and concurrently improves mechanical performance) by LV unloading. During reperfusion exclusively, IABP support also improves LV contractility and active relaxation, possibly due to a synergistic effect of unloading and augmentation of coronary blood flow.

Outcome of emergency coronary artery bypass grafting

OBJECTIVES

The aim of this study was to evaluate the immediate and late outcome of emergency coronary artery bypass grafting (CABG) in a multicenter setting.

DESIGN

Multicenter, retrospective study.

SETTING

Four university hospitals.

PARTICIPANTS

596 patients were included in this study.

INTERVENTIONS

Included patients underwent isolated, emergency CABG.

MEASUREMENTS AND MAIN RESULTS

Sixty patients (absolute rate: 10.1%, pooled rate: 8.7%) died during the in-hospital stay period. Increasing emergency CABG classes (p<0.0001), recent myocardial infarction (p=0.019), left ventricular ejection fraction≤30% (p=0.034), on-pump surgery (p=0.012), and participating centers (p<0.0001) were independent predictors of in-hospital mortality. Survival rates at 1, 3, and 5 years were 86.4%, 81.6%, and 76.1%, respectively. Extracorporeal membrane oxygenation was used in 6 patients and 3 of them (50.0%) survived the immediate postoperative period. Patient populations of participating centers differed significantly in most of baseline characteristics. The preoperative use of intra-aortic balloon pump (8% to 51%) and off-pump surgery (2.8% to 56.3%) varied significantly between institutions. In-hospital mortality (2.8%, 5.9%, 7.7% and 19.8%, p<0.0001), as well as midterm survival, significantly differed between institutions (at 3 years, 90.6%, 89.8%, 81.2%, and 67.2%, p<0.0001).

CONCLUSIONS

The outcome after emergency CABG is satisfactory despite a significant operative risk. However, the results of emergency CABG significantly differed between the participating institutions, likely due to differences in the referral pathways and perioperative treatment strategies. Evaluation of these factors is crucial for implementation of treatment in centers with suboptimal results.

Intra-aortic balloon counterpulsation in acute myocardial infarction: old and emerging indications

Background

Recent evidence questions the role of intra-aortic balloon counterpulsation (IABP) in the treatment of acute myocardial infarction (AMI) complicated by cardiogenic shock (CS). An area of increasing interest is the use of IABP for persistent ischaemia (PI). We analysed the use of IABP in patients with AMI complicated by CS or PI.

Methods

From 2008 to 2010, a total of 4076 patients were admitted to our hospital for primary percutaneous coronary intervention (PCI) for AMI. Out of those, 239 patients received an IABP either because of CS or because of PI. Characteristics and outcome of those patients are investigated.

Results

The mean age of the study population was 64 ± 11 years; 75 % were male patients. Of the patients, 63 % had CS and 37 % had PI. Patients with CS had a 30-day mortality rate of 36 %; 1-year mortality was 41 %. Patients with PI had a 30-day mortality rate of 7 %; 1-year mortality was 11 %.

Conclusions

Mortality in patients admitted for primary PCI because of AMI complicated by CS is high despite IABP use. Outcome in patients treated with IABP for PI is favourable and mandates further prospective studies.