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Spieker et al. Vessel Plus 2020;4:29 I http://dx.doi.org/10.20517/2574-1209.2020.28 Page 3 of 11

course of patients in whom this single follow-up examination in our department was deemed impossible
was monitored by telephone interview with referring cardiologists and the patients’ primary physicians or
the patients themselves. The primary endpoint of the study included a composite of all-cause mortality or
hospitalization for heart failure during 12 months follow-up. Hospitalization for heart failure was defined
by clinical symptoms suggestive of heart failure (e.g., worsening of dyspnea, edema and fatigue) and the
need for i.v. diuretics during re-hospitalization. Secondary endpoint was reduction in New York Heart
Association (NYHA) functional class at 12 months following PMVR compared to baseline.

Echocardiographic evaluation
Echocardiographic examinations were performed using a GE Vivid S6/E9 or a Philips iE33. All
echocardiographic data were stored on a workstation for offline analysis (Xcelera Cardiology Information
Management, Philips). Left ventricular volumes and ejection fraction were calculated using the Simpson
biplane method. Systolic pulmonary artery pressure (SPAP) was estimated from the regurgitant jet of
tricuspid regurgitation with peak systolic trans-tricuspid pressure gradient. Assessment of MR was
[4]
performed according to current guidelines . MR severity was assessed by an integrative approach using
semi-quantitative [vena contracta (VC)] and quantitative (EROA, RVol) parameters. The severity of MR
was graded mild (1+), moderate (2+) and severe (3+). In patients with secondary MR, the cutoff values
2
for severe MR were: EROA 20 mm and RVol 30 mL, according to current guidelines . The radius of the
[4]
maximal proximal iso-velocity surface area (PISA) was measured using several frames. The largest radius
was selected for analysis. RVol and EROA were calculated with standard formulae as previously described.
For semi-quantitative assessment, VC width was assessed from the apical four-chamber view. The largest
VC diameter was measured for three cardiac cycles and averaged. Patients presenting with moderate MR at
rest and severe MR during handgrip exercise were assigned “dynamic severe MR”.

Handgrip exercise
Following comprehensive echocardiographic examination at rest, handgrip exercise was performed
according to a standardized protocol with a handgrip dynamometer (Jamar® Hydraulic Hand
Dynamometer, Sammons Preston Inc.) while the patient lay on his/her left side. After initial recording of
blood pressure and heart rate at rest, the patient was asked to squeeze the dynamometer with maximum
effort for a short period only. The handgrip exercise was then carried out at half-maximum force for three
minutes, while echocardiographic data were obtained focusing on MR and SPAP. Blood pressure and
heart rate were recorded every minute. MR was quantified as indicated above, including measurement of
PISA, VC, EROA and RVol. In case of non-reproducible results according to the PISA method (e.g., due
to eccentric jets in 8 of 93 patients), VC width was used for assessment of MR severity. Medical therapy
(including ß-blockers) remained unchanged for the exercise test.

Statistical analysis
All analyses were performed using Sigma Plot software (Version 11.0, Systat Software Ltd). Results are
expressed as mean ± standard deviation or percentage unless otherwise specified. Normality distribution
was assessed with the Kolmogorov-Smirnov test. A two-tailed paired t-test was used to compare differences
between two groups. Fisher’s exact test was used to investigate the significance of the association between
two kinds of classification. Differences between three groups were assessed by one-way ANOVA with post-
hoc Tukey correction for multiple comparisons. The Kaplan-Meier method and the log-rank test were used
for presenting the event-free rate. For all analyses, a P-value of < 0.05 was considered statistically significant

RESULTS
We included 221 patients who underwent PMVR with the MitraClip system. Ninety-three patients with
moderate to severe MR at rest received handgrip echocardiography prior to MitraClip implantation
[Figure 1]. The remaining 128 patients presented with clinically relevant severe MR at rest, making exercise
echocardiography unnecessary.