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Page 8 of 17 Cannata et al. Mini-invasive Surg 2020;4:53 I http://dx.doi.org/10.20517/2574-1225.2020.41

Finally, rheumatic heart disease is commonly regarded as a contraindication to MitraClip procedures,
owing to high risk of mitral stenosis. However, a recently published case report has shown the feasibility of
[26]
percutaneous MV repair in a rheumatic MV with baseline mean gradients inferior to 4 mmHg . Accurate
measurement of MV area through 3D-based multiplanar reconstruction, evaluation of trans-mitral
mean gradients and exclusion of calcifications at the grasping area are essential to decision-making and
preoperative planning.

[27]
As outlined above, absolute anatomic limitations are very few. Hahn listed the echocardiographic
features associated with ideal and challenging anatomies and highlighted a few relative contraindications.
The absolute contraindications include severe and extended calcifications of the grasping zone, short leaflet
[15]
length (< 7 mm) and small baseline MV area (< 3.5 cm²) .

Real-world evidences of MitraClip procedure in acute MR
Real-world experience on percutaneous edge-to-edge repair of acute MR is uniquely derived from case
reports and small-size registries, listed and synthetized in Table 2 [19,28-43] .

The vast majority of cases occurred as complications of acute myocardial infarction, due to either ischemic
leaflet tethering or papillary muscle ruptures (more often the posteromedial one). A primary PCI was
always performed, except for late presentations due to the likely risk of reperfusion injury of already
necrotic walls. The hemodynamic status was generally critical with evidence of cardiogenic shock and
pulmonary edema requiring intubation, inotropes and mechanical support, mainly IABP and only in few
cases veno-arterial extracorporeal membrane oxygenation. The Heart Team’s decision to proceed with
MitraClip was primarily guided by the high surgical risk due to hemodynamic instability, acute/subacute
ischemia, dual antiplatelet therapy, advanced age or comorbidities in a few cases, and the favourable risk-
benefit balance of percutaneous edge-to-edge approach. Hemodynamic stabilization and likeliness of
MR improvement with revascularization or medical therapy were the main determinants of the timing of
procedure. One to three clips were deployed with an almost complete procedural success, due to significant
[42]
reduction of MR, huge reduction of left atrial pressures and increase of cardiac output. Haberman et al.
reported one case of posterior leaflet tear during a second clip implantation, followed by urgent MV
surgery and lastly by patient death. Early outcomes were promising, with high survival rates, sustained
reduction of MR grade and improved functional class. These results are even more reassuring if compared
with surgical ones; in a multicentre surgical registry of 279 patients treated with emergency surgery for
acute severe MR, due to myocardial infarction, acute endocarditis or degenerative MV disease, the 30-day
mortality was 22.5% with worse survival rates in case of acute myocardial infarction, endocarditis, shock,
[44]
coronary artery disease and systolic dysfunction . Despite the evidences seem extremely optimistic
regarding outcomes of MitraClip in almost every acute setting, a publication bias has to be recognized, and
the interventionalists’ and imagers’ experience should be considered during Heart Team decision-making.
Certainly, MitraClip shows several advantages over surgery. Firstly, MitraClip is safe and does not preclude
a delayed surgical procedure in case of failure, thus a “bridge” procedure may be always attempted without
significant additional risks. Secondly, percutaneous procedures permit to avoid the cardiopulmonary
bypass and the associated systemic inflammatory storm and myocardial oxidative stress. Furthermore,
transcatheter procedures do not cause abnormal motion of the right ventricle or interventricular septum,
[43]
which may impact on long-term LV performance .

Decision-making and management
We propose a flow-chart that may be helpful for acute MR decision-making and management [Figure 5].

Once acute MR is diagnosed, the initial goal is hemodynamic stabilization through inotropes/vasopressors
and temporary mechanical circulatory supports (IABP, Impella and extracorporeal membrane oxygenation)