Authors’ response
We thank Orhan Gokalp et al. for their interest in our article. Acute myocardial infarction (AMI) is the most frequent cause of cardiogenic shock (CS) accounting for about 80% of cases [2]. The most severe cases of CS can be treated with mechanical circulatory support, as a bridge to recovery of cardiac function, or as a bridge to heart transplantation or sometimes as a bridge to another device. Veno-arterial (VA)-extracorporeal membrane oxygenation (ECMO) technique is nowadays widely recognized as an efficient assist device and easy to implant, providing high cardiac output and respiratory support [3]. Although randomized clinical trials are lacking, several nonrandomized studies suggest a survival advantage from the early use of ECMO in CS. In a study published with 138 patients, 65 (47%) patients survived to ICU discharge. However, ECMO complications occurred in 39% of the patients [4]. A common drawback of this modality is a resultant increase in left ventricular afterload. This phenomenon results in the retrograde aortic flow, which causes a marked increase in the left ventricular (LV) afterload, which might impair myocardial recovery. The consequences of this phenomenon are left ventricular distension and increase of left ventricular end-diastole pressure (LVEDP), leading to severe pulmonary edema, increased wall stress, and myocardial oxygen consumption. About 35% of ECMO patients present left ventricular distension, and 16% requires an intervention to decompress the LV [5]. A recent meta-analysis included 3997 patients, with 1696 (42%) receiving a concomitant left ventricular unloading strategy while on VA-ECMO (intra-aortic balloon pump 91.7%, percutaneous ventricular assist device 5.5%, and pulmonary vein or transseptal left atrial cannulation 2.8%). Mortality was lower in patients with (54%) versus without (65%) left ventricular unloading while on VA-ECMO (risk ratio, 0.79; p < 0.00001) [6]. Furthermore, recent results analyzing patients treated with concomitant VA-ECMO and Impella have shown a significantly lower in-hospital mortality and a higher rate of successful bridging to either recovery or next therapy as compared to VA-ECMO alone [7].
We do not agree with the authors that instead of VA-ECMO, it would be more appropriate to use devices such as TandemHeart or Impella, in which the left ventricle is vented in patients with a higher likelihood of recovery. We strongly believe that ECMO is the most appropriate device for severe cases of CS and that unloading the left ventricle is essential. A device such as IMPELLA might be the best option to decrease afterload and should be inserted concomitantly (ECMELLA). Moreover, as recently published, a standardized team-based approach may improve CS outcomes, increasing significantly 30-day survival from 47 to 76.6% [8]. Prompt recognition, advanced monitoring, adequate reperfusion strategies, and early implant of mechanical circulatory support are essential to improve outcomes in cardiogenic shock.