Pulmonary Decongestion May Facilitate Treatment of Pneumonia in Patients with Cardiogenic Shock

Patrick Horn, MD, discusses results of his recently published paper in Open Heart investigating the impact of left ventricular unloading on pulmonary congestion and pneumonia in patients with cardiogenic shock. Dr. Horn is an interventional cardiologist and head of the cath lab at The University Hospital in Düsseldorf, Germany. His paper is titled “Percutaneous left ventricular assist support is associated with less pulmonary congestion and lower rate of pneumonia in patients with cardiogenic shock.”

Dr. Horn explains that this area of investigation was important because 2 out of 3 patients with cardiogenic shock will develop pulmonary congestion due to left ventricular failure and this can create a breeding ground for pneumonia. Thus, the aim of the study was to assess whether left ventricular unloading with the Impella® heart pump decreased primary congestion and whether this might prevent the development of pneumonia. 

This retrospective study compared Impella support with intra-aortic balloon pump (IABP) support in patients with cardiogenic shock primarily caused by acute myocardial infarction. The primary endpoint of the study was pulmonary congestion and development of pneumonia and early mortality were the secondary endpoints. Most of the patients had high organ failure assessment scores and were at shock stage D or E. At baseline, both groups had similar marked pulmonary congestion as indicated by high Halperin score.

Describing the results shown in Figure 2 in the paper, Dr. Horn highlights that pulmonary congestion decreased during Impella support but not during balloon pump support. He emphasizes, “most patients in the Impella group were decongested to a lower classification of the congestion.”

Regarding the multivariate regression analysis in Table 3 of the paper, Dr. Horn explains “Impella support was an independent predictor for pulmonary decongestion… You can also see that early pneumonia was independently predicted by failure of pulmonary decongestion during MCS support.”

“Decongestion most likely occurs by recovery of cardiac function or by ventricular unloading, both leading to reduced ventricular pressure,” Dr. Horn explains. “In other words, unloading of the left ventricle and atrium favors forward flow through the primary circulation. This might decrease pulmonary capillary hydrostatic filling pressures and thereby promote the decongestion. And the decongestion was associated in our study with lower rate of pneumonia, or, in other words, Impella supported a number needed to treat of 5 to avoid 1 case of pneumonia.”

When asked to describe the impact of these results on patient care in cardiogenic shock, Dr. Horn concluded, “Whatever we do, we should reduce pulmonary congestion in our patients with shock.” He also explained, “Impella, in patients with shock, may exert beneficial effects beyond hemodynamic stabilization by effecting this lung congestion.”