Author + information
- Tasneem Z. Naqvi, MD∗ ( and )
- Michael B. Gotway, MD
- ↵∗Mayo Clinic, 13400 East Shea Boulevard, Scottsdale, Arizona 85259
We read with interest the article by Uretsky et al. (1) and would like to provide a few comments. The investigators did not describe if they included patients with atrial fibrillation and the number of cardiac cycles used to assess mitral regurgitation (MR) by both echocardiography and magnetic resonance imaging (MRI) in such patients. In the presence of atrial fibrillation, variable RR intervals might affect both echocardiography and MR calculations. With respect to loading conditions, the overall group’s mean values for blood pressure (BP) and heart rate (HR) were comparable; however, the SD suggests that, for an individual patient, BP and HR at the time of echocardiography and MRI were likely not comparable. It is also possible that MRI underestimated MR volume in patients with mild aortic regurgitation (AR), especially if AR was more than mild and underestimated (we were not informed on how the severity of AR was quantified). Table 4 shows that patients with a progressive increase in MR severity as seen by MRI had a progressive increase in left ventricular (LV) end-diastolic diameter. LVEDD was 5.09 ± 0.60 cm, 5.23 ± 0.66 cm, and 6.11 ± 0.59 cm, respectively, and LV end-systolic diameter was 3.41 ± 0.50 cm, 3.47 ± 0.73 cm, and 4.07 ± 0.53 cm, respectively, in mild, moderate, and severe MR by MRI. Because MR severity was calculated using LV end-diastolic volume (EDV), the higher the LVEDV, the more severe the MR according to MRI. Therefore, in the presence of normal LV size (and EDV), MRI is likely to underestimate MR severity. In addition, patients with higher LVEDVs are expected to have a greater reduction in LVEDV post-MR surgery than those with a normal LVEDV. Thus, instead of concluding that MRI is a better method to assess MR severity, the study showed that increased LV volumes pre-MR surgery predicted recovery of LVEDV post-MR surgery. Careful assessment of MR by using comprehensive echocardiographic methodology in studies with similar (2) or a larger sample size and blinded core laboratory assessment (3) showed LV reverse remodeling after percutaneous mitral valve repair, which indicates that echocardiography is able to select appropriate surgical candidates by quantifying MR accurately. Figure 2 shows a patient in whom MR was quantified as severe by echocardiography and mild by MRI. LV enlargement, posterior leaflet prolapse, and color Doppler suggest more than mild MR. Reverse remodeling post-surgery in this patient indicates appropriate echocardiography MR assessment.
The study also had a small sample size of 26 patients because 7 were not yet due for follow-up. Transesophageal echocardiography (TEE) was performed in only 37% of study patients. It remains unclear if the agreement in 37 patients between echocardiography and MRI was based on transthoracic echocardiography or TEE, and how many TEEs were included in the subset of 93 patients in whom variability of MR severity was assessed. TEE allows a more comprehensive assessment of the mitral valve and MR. The wide scatter in agreement for MR between readers 1 and 2 might be related to varying reader expertise and/or comprehensiveness and the quality of echocardiography studies. Finally, some of the nuances of MRI post-processing, notably whether the papillary muscles and/or LV trabeculations were included in ventricular volume tracings (which could affect LV volume quantification ) were incompletely described.
Please note: Both authors have reported that they have no relationships relevant to the contents of this paper to disclose.
- American College of Cardiology Foundation
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