The Rubber Hits the Road and Impella Mechanical Circulatory Support Falls Flat

Mechanical Circulatory Support for High Risk PCI

Dr. Amit P. Amin presented comparative effectiveness data on length of stay and costs of Impella vs. IABP among patients undergoing PCI with mechanical circulatory support (MCS) for high-risk PCI or cardiogenic shock. Using the Premier Healthcare Database (PHD), they developed a propensity score using multivariable logistic regression to analyze 48,306 PCI patients from 432 hospitals between January 2004 and December 2016 who underwent PCI with mechanical circulatory support for high-risk PCI or cardiogenic shock. Adverse outcomes and costs were higher in the Impella-era (years 2008–2016) vs. the pre-Impella era (years 2004–2007). Hospitals with higher Impella use had higher rates of adverse outcomes and costs. After adjustment for the propensity score, and accounting for clustering of patients by hospitals, Impella use was associated with death: OR 1.24 (95%CI 1.13-1.36); bleeding: OR 1.10 (95%CI 1.00-1.21); and stroke: OR 1.34 (95%CI 1.18-1.53), although a similar, non-significant result was observed for AKI: OR 1.08 (95%CI 1.00-1.17). They concluded that Impella use is rapidly increasing among PCI patients treated with MCS, with marked variability in its use and associated outcomes. They found that Impella use was associated with higher rates of adverse events and higher costs and called for comparative data to define the appropriate role of MCS, if any, in patients undergoing high risk PCI.

Mortality and Bleeding Among Patients With Acute Myocardial Infarction Complicated by Cardiogenic Shock Undergoing Percutaneous Coronary Intervention With Impella vs Intra-Aortic Balloon Pump 

Dr. Sanket Dhruva presented data from the National Cardiovascular Data Registry (NCDR) to characterize mechanical circulatory support (MCS) utilization and outcomes among patients with acute myocardial infarction (AMI) with cardiogenic shock (CS) receiving either Impella or intra-aortic balloon pump (IABP). With propensity score matching among 28,304 eligible AMI-CS patients they found Q4 2015 to Q4 2017, there was a significant increase in Impella utilization (from 3.5% to 8.7%) and a concomitant decrease in IABP utilization (32.1% to 27.3%; p<0.001 for both). In-hospital death (45% vs 34.1%) and major bleeding rates (31.3% vs 16%) were significantly greater among patients receiving Impella compared to IABP. They concluded that despite the limitations of observational data, these data highlight the need for more robust evidence to demonstrate the superiority of the Impella in patients with AMI-CS. 

Interventionalists face very difficult decisions when performing PCI for highly complex patients who may or may not require hemodynamic support. We are often influenced by "anecdote," in the absence of comparative evidence. My impression is that increased Impella use has been fueled by small, non-comparative studies that rely on marketing techniques (single arm trials) to promote the use of the Impella. Industry sponsors are often reluctant to support randomized trials, unless they are sure their device will win. Just like a forward pass in football, there are three potential outcomes, and two of them are bad for companies with large investments in their technology. Given the increased risks and costs associated with Impella use described in the two abstracts above, the time has come for the sponsor to "put up, or shut up" for comparative trials that can answer the question of which patients, if any, would benefit from the use of this device. 

Out of Hospital Cardiac Arrest Patients without STEMI Should Be Managed Conservatively

Jorrit Lemkes presented the one year follow-up of The COronary Angiography after Cardiac arresT (COACT) trial, a randomized study of the effect of an immediate coronary angiography (CAG) and percutaneous coronary intervention (PCI). PCI was only necessary in patients successfully resuscitated after out of hospital cardiac arrest (OHCA) in the absence of ST segment elevation (STEMI), compared to a delayed invasive strategy. They have previously reported no difference at 90 days. They now present the one year clinical outcome of the COACT trial in 552 OHCA patients without STEMI, who were randomized in a 1:1 ratio to an immediate or a delayed invasive strategy for the occurrence of major cardiac events (MACE) at one year. They found no difference in survival at one year, rates of myocardial infarction, need for revascularization, ICD shocks, or need for hospitalization for heart failure between the immediate and delayed groups. 

The management of OHCA survivors has been uncertain and many interventionalists have given the benefit of doubt in taking all patients for urgent cath leading to concerns over futility in patients who never recover neurologic function. The data now seem much clearer that patients with OHCA and STEMI should be emergently treated in the cath lab upon presentation, while those patients surviving OHCA without ST elevation can be managed more conservatively, allowing better selection for patients more likely to benefit from PCI. 

Christopher J. White MD; MACC, MSCAI, FAHA, FACP, FESC is a System Chairman for Cardiovascular Diseases at Ochsner Health System in New Orleans, LA.

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