It was with great interest that we read the article published by Delmas et al.,1 which is a European multicenter survey on the use of Impella devices as a bridge to surgical repair, bridge to percutaneous closure, or bridge to recovery/no intervention. This study included 28 patients with postmyocardial infarction ventricular septal ruptures (post-MI VSRs), who were all in cardiogenic shock upon presentation. Impella devices used were Impella 2.5 (3.5%, 1/28), Impella CP (71%, 20/28), Impella 5.0 (18%. 5/28), and unknown for 7% (2/28). Additional temporary mechanical circulatory support (MCS) was required in 50% of cases, mainly extracorporeal membrane oxygenation (ECMO) (32%). Definitive treatment of post-MI VSR for patients supported with Impella was surgical in 36%, percutaneous in 21%, and conservative management in 43%. In-hospital mortality was 75%, and survival at 1 year was also 25%. Only patients who were definitively treated with surgery survived. Access site severe bleeding (50%) and hemolysis (11%) were the most common Impella-associated complications.

Because primary percutaneous coronary intervention (PCI) became the mainstay for treating acute ST elevation myocardial infarctions (STEMI), the occurrence of post-MI VSRs has steadily declined, with a current incidence of approximately 0.3%.2 Nevertheless, when it does occur, it is associated with extremely high mortality, owing to a combination of cardiogenic shock and technical difficulties of repairing these defects, given that surgeons must often deal with poorly delineated, infarcted, and fragile tissue.3 Delayed surgical repair (>7 days) is associated with better survival (54%) compared to early repair (18%).4 Furthermore, 38% of VSRs repaired with early surgery have evidence of recurrent ventricular septal defect (VSD).5 As a result, it is important to wait for at least a week from the occurrence of the VSR until definitive surgical repair, as this is associated with higher rates of survival. Traditionally, most patients have been supported with an intra-aortic balloon pump (IABP). However, IABP may not be sufficient to hemodynamically support a patient,6 but is also associated with peripheral thrombotic complications and does not allow patients to ambulate. Veno-arterial (VA) ECMO can increase left ventricular (LV) afterload, worsen left-to-right shunting, and is usually avoided as a sole means of MCS in post-MI VSRs. Nonetheless, few case series, including this study by Delmas et al.,1 have demonstrated successful LV unloading and hemodynamic support with Impella, for patients with post-MI VSRs, before surgical repair.7,8 The use of Impella devices for VSRs is relatively contraindicated, as it can theoretically reverse the shunt causing hypoxia and can also dislodge the fragile infarcted septal tissue causing distal embolization, including stroke. Our experience has not shown this and we feel that these devices should be strongly considered, when balancing the management of VSRs between stabilization of hemodynamics, organ recovery, and surgical timing for improved outcomes.

The use of Impella devices, as a bridge to surgery in post-MI VSR patients, has become even more advantageous with the introduction of the Impella 5.5, especially in the axillary artery position. Of course, one must weigh the risks of surgically implanting an Impella 5.5 for patients in cardiogenic shock against the potential benefits. We do feel that these risks are minimal and the benefits are great, especially given that the procedure is generally quick and straightforward. Many of these patients will already be intubated, and placing an Impella 5.5, will allow for early potential extubation and even ambulation, which is of critical importance for maximizing postoperative survival. Traditionally, most VSR patients receive an IABP. Intra-aortic balloon pump insertion, especially in the femoral position, requires patient immobilization, which is detrimental for surgical candidates, owing to worsening pulmonary function from V/Q mismatch, muscle wasting, and malnutrition, and is also associated with a higher risk of deep vein thrombosis/pulmonary embolism (DVTs/PE), peripheral/visceral thrombotic complications, worsening end-organ perfusion (renal, hepatic, mesenteric failure), inability to maintain hemodynamics and perfusion and resultant higher pressor and inotropic requirements. This is also true of earlier generation Impella devices placed in the femoral position. We strongly feel that these limitations are mitigated with an axillary Impella 5.5, and should be considered in all patients with post-MI VSR, especially those in cardiogenic shock.

There has only been one report in which Impella support resulted in a right-to-left shunt.9 Right-to-left shunt should only happen with high Impella flows, and this can be easily managed by decreasing the amount of support. Sato et al.10 demonstrated that shunt reversal only occurred at support levels of P8 or higher and by lowering support to P6, they were able to convert the shunt back to left-to-right, thus eliminating systemic deoxygenation. There have been no reports of systemic embolization or strokes using Impella in post-MI VSRs. Direct intake of tissue by the device is doubtful. If tissue fragments enter the pump, it would alarm and shut off, which makes embolization through the Impella highly unlikely.

Recently, Ruiz Duque et al.8 published a case series of four patients with post-MI VSRs who were supported with Impella before surgical repair. All of their patients survived postoperatively. They also demonstrated a decrease in wedge pressure, decrease in left-to-right shunting, reduction in trans-VSD gradients, and improvement in end-organ perfusion before VSR closure. The authors proposed the use of Impella in patients with Qp/Qs of greater than 2.5.

Despite our endorsement for using Impella devices in patients with post-MI VSRs, we have some comments on this article by Delmas et al.1 The inclusion of the Impella 2.5 and Impella 5 in the study, is clinically irrelevant, because both devices are rarely, if ever, used and have been largely replaced by their successors, the Impella CP and the Impella 5.5, respectively, which are both far superior. They report that severe access site hemorrhage was their most common complication (50%), followed by hemolysis (12%). The new generation Impella 5.5, which runs bicarbonate in the purge, lessens the need for early systemic heparinization and significantly reduces the risk of bleeding. Also, the risk of hemolysis with the larger 5.5 device has been significantly reduced compared with previous generation Impellas. They also mention that VSD patch closure is performed through a double ventriculotomy, which seems unnecessary, as most VSRs can generally be repaired through a single left or right ventriculotomy, depending on the location of the infarct and resultant VSR. The lack of hemodynamic and echocardiographic data is a shortcoming, as it would have been instructive to see the changes in LV loading, LV dimensions, LV pressures, VSR gradients, and Qp/Qs ratios before and after Impella therapy, both with and without additional MCS. These data would have shown the true benefit of Impella support in patients with post-MI VSRs. Finally, this study clearly confirms that surgical repair is the best and possibly only definitive treatment for VSRs. Successful transcatheter device closure is rarely possible owing to the larger size of typical post-MI VSRs, their challenging anatomic location for percutaneous closure, and the poor quality of tissue which constitutes the rim on which the device will be secured.

In conclusion, Impella support for patients with post-MI VSRs should be strongly considered, especially in the context of cardiogenic shock and high Qp/Qs gradients. These heart pumps are well-established for shifting LV pressure-volume loops by decreasing filling pressures and volumes. It comes as no surprise that Impella devices decrease shunting across VSRs and increase total systemic flow to the body. This allows for end-organ recovery and for ischemic septal tissue to delineate and mature, making surgical VSR repairs much safer and durable. The usage of axillary Impella 5.5 is even more advantageous, given its association with less bleeding complications and less hemolysis. Additionally, and perhaps most importantly, the Impella 5.5 allows for early ambulation and preoperative optimization in a critically ill patient population.

1. Delmas C, Barbosa H, David C-H, et al.: Impella for the management of ventricular septal defect complicating acute myocardial infarction: An European multicenter registry. ASAIO J. 69: 2023. 2. Elbadawi A, Elgendy IY, Mahmoud K, et al.: Temporal trends and outcomes of mechanical complications in patients with acute myocardial infarction. JACC Cardiovasc Interv. 12: 1825–1836, 2019. 3. Giblett JP, Matetic A, Jenkins D, et al.: Post-infarction ventricular septal defect: Percutaneous or surgical management in the UK national registry. Eur Heart J. 43: 5020–5032, 2022. 4. Via G, Buson S, Tavazzi G, et al.: Early cardiac unloading with ImpellaCP™ in acute myocardial infarction with ventricular septal defect. ESC Heart Fail. 7: 708–713, 2020. 5. Cinq-Mars A, Voisine P, Dagenais F, et al.: Risk factors of mortality after surgical correction of ventricular septal defect following myocardial infarction: Retrospective analysis and review of the literature. Int J Cardiol. 206: 27–36, 2016. 6. Hobbs R, Korutla V, Suzuki Y, Acker M, Vallabhajosyula P: Mechanical circulatory support as a bridge to definitive surgical repair after post-myocardial infarct ventricular septal defect. J Card Surg. 30: 535–540, 2015. 7. La Torre MW, Centofanti P, Attisani M, Patanè F, Rinaldi M: Posterior ventricular septal defect in presence of cardiogenic shock: Early implantation of the Impella recover LP 50 as a bridge to surgery. Tex Heart Inst J. 38: 42–49, 2011. 8. Ruiz Duque E, Hohenwarter MR, Isom NR, Singhal AK: Impella support for surgical ventricular septal defect repair. ASAIO J. 69: e278–e283, 2023. 9. Maeda K, Yoshioka I, Saiki Y: Emergence of right to left shunt via postmyocardial infarction ventricular septal defect under Impella support. Artif Organs. 45: 316–317, 2021. 10. Sato S, Hiraoka A, Toki M, Chikazawa G, Yoshitaka H: Right-to-left shunt depending on the support level of Impella for post-infarction ventricular septal defect. Eur Heart J Cardiovasc Imaging. 23: e296, 2022.