The progression of myocardial remodeling and perfusion changes in patients with moderate aortic stenosis (RF_TH_211)

Aim:  Aortic stenosis (AS) accounts for substantial global morbidity and premature mortality even in moderate AS (Mod-AS). The rate of myocardial remodeling progression in patients with mod-AS is unclear.



Methods:

Methods:  Twenty-five Mod-AS patients were prospectively recruited and followed up for a period of 18 months to assess the progression of the degree of valvular stenosis as well as myocardial remodeling. Patients underwent a baseline cardiovascular magnetic resonance (CMR)  at baseline to define left ventricular (LV) concentricity (LV-mass/LV-end-diastolic-volume), global longitudinal shortening (GLS), mitral inflow E/A ratio, rest and adenosine-stress myocardial blood flow (MBF), myocardial perfusion reserve (MPR), layer-specific perfusion metrics (subendocardial [Endo], subepicardial [Epi] MBF and MPR, and Endo- to Epi-MBF ratio [Endo/Epi]), tissue characterization (late gadolinium enhancement imaging [LGE]) at baseline. Identical follow-up CMR scans were performed at 12 months in 18 patients.



Results:

Results:  Compared to baseline visit there were no significant biochemical or anthropometric differences at 12-month CMR scan performed at Visit-2 (Table-1).

Over the 12-months period, there was a significant decline in stress-MBF (Visit-1:1.9[1.6,2.2] vs Visit-2:1.4[1.2,2.6]ml/min/g; P=0.006) and MPR (Visit-1:2.8[2.4,3.2] vs Visit-2: 2.3[1.9,2.6]ml/min/g; P=0.04). In parallel with the global perfusion indices, the layer-specific perfusion parameters also showed significant reductions over a 12-month period including the Endo-stress-MBF (Visit-1: 1.7[1.5,2.0] vs Visit-2: 1.2[1.1,1.4]ml/min/g; P=0.0015) and Epi-stress-MBF(Visit-1:2.0[1.7,2.3] vs Visit-2:1.5[1.3,1.7]ml/min/g; P=0.0180)(Figure-1).

Moreover, patients with Mod-AS exhibited a progressive numerical increase in LV concentricity which did not reach statistical significance (Visit-1: 0.74[0.64,0.84] vs Visit-2: 0.84[0.73,0.96]g/mL; P=0.1548). An increasingly restrictive filling pattern was exhibited as measured by E/A ratio (Visit-1: 1.3[1.0,1.5] vs Visit-2: 2.0[1.5,2.6]; P=0.042).  While there was no significant change in LV ejection fraction or GLS (Table-2), there was a significant decline in left atrial function (Visit-1: 59[52,66] vs Visit-2:47[41,53]%; P=0.0158). There was also a subtle numerical but non-significant increase in non-ischemic pattern of myocardial scar on LGE (Table-1).

Seven patients progressed to severe-AS, requiring valve intervention at the 18-month censor point. A retrospective subgroup analysis revealed that this group of patients had significantly worse stress-MBF at baseline CMR scan (Mod-AS progressed to Severe-AS:1.6[1.4,1.8], Mod-AS did not progress to Severe-AS:2.0[1.7,2.4]ml/min/g;  P=0.0375) compared to patients who did not progress to Severe-AS over the 18-month clinical follow-up period (Table-2).



Conclusion:

Conclusions:  Over a period of 12 months, patients with Mod-AS exhibited marked significant deterioration of myocardial perfusion despite less pronounced changes in cardiac concentric hypertrophy and no significant change in LV systolic function on CMR. Patients who progressed to severe-AS over the clinical follow-up period showed worse myocardial perfusion at baseline despite matching AS severity to those who did not progress to severe-AS.