Aortic, Mitral Regurgitant Volume May Predict Cardiac Function in Asymptomatic Patients

Among asymptomatic patients with aortic or mitral regurgitation, cardiac function remains stable over 3 years in those with moderate disease but worsens in those with severe disease, according to a study published online December 10, 2014, ahead of print in JACC: Cardiovascular Imaging.

As such, “frequent echocardiography without a change in clinical status may not be necessary,” the authors suggest.

But in a telephone interview with TCTMD, Ted Feldman, MD, of Evanston Hospital (Evanston, IL), said “they're reaching a little far with that suggestion” given the small population and the lack of information on etiology.

Researchers led by Zoran B. Popović, MD, PhD, looked at 698 consecutive patients undergoing exercise echocardiography with left-side valvular disease and preserved ejection fraction. The final cohort, which excluded 319 patients lost to follow-up, matched 130 patients with moderate-to-severe asymptomatic mitral regurgitation (average age 54 years; 68% men) with 130 patients with moderate-to-severe asymptomatic aortic regurgitation (average age 54 years; 77% men). Patients were further classified by regurgitant volume index into moderate (< 30 ml/m²) or severe (≥ 30 ml/m²) groups.

After 3 years of echocardiographic follow-up, 41% and 19% of patients with mitral and aortic regurgitation, respectively, had valve surgery. Also, 7% and 4% worsened from moderate to severe. In a subset of patients who underwent open heart surgery, no significant CAD was found.

Left ventricular end-diastolic volume index (LVEDVI) was larger in patients with severe vs moderate disease and in those with aortic vs mitral disease (P < .001 for both). While LVEDVI increased with severe regurgitation at a rate of 4.2 ± 1.5 mL/m² per year (P = .01) independent of etiology, there were no changes over time in patients with moderate regurgitation.

Left ventricular end-systolic volume index (LVESVI) was also larger in those with severe (P = .002) and aortic lesions (P < .001). This measurement increased at a rate of 2.5 ± 0.7 mL/m² per year (P = .001) in patients with severe regurgitation, and there were again no changes observed within the moderate group.

LVEF was lower in patients with aortic vs mitral regurgitation (P < .001), but there was no link between this factor and regurgitation severity. LVEF remained stable in patients with moderate regurgitation, but it decreased at a rate of 1.3 ± 0.4% per year (P = .002) in patients with severe disease.

Patients with severe regurgitation reported a drop in contractility regardless of etiology, but there was no change in patients with moderate regurgitation.

Enough to Substantiate Change?

“The earlier premise was that [aortic] and [mitral regurgitation] of moderate-to-severe grade tends to progress, leading to a worsening of hemodynamic status and ultimately to clinical symptoms,” Dr. Popović and colleagues write. “Accordingly, previous guidelines recommended ‘repeat echocardiography at yearly intervals in patients with moderate MR,’ and recent guidelines also recommend that patients with moderate severity should be followed up every 1 to 2 years.”

But this study suggests “that moderate regurgitation, at least in this population, remained stable during 3 years of follow-up…,” they continue. “Thus, careful assessment of symptoms in patients with moderate regurgitation is even more relevant if one opts not to perform routine yearly echocardiographic follow-up evaluations.”

They claim that grouping aortic and mitral regurgitation patients together and assessing regurgitant volume “provide[s] further insight into the natural history” of the diseases. “Initially, compensatory mechanisms of the moderate [aortic and mitral regurgitation] are distinct but likely efficient over many years given the stability that we have shown,” the authors write. “However, once a regurgitant volume threshold is exceeded, a more rapid decline occurs.”

Dr. Feldman called the study design “unusual” because “aortic and mitral regurgitation are very different diseases.” Given the small patient population, information provided in subgroup analyses would still need to be confirmed and further interpreted, he said.

Dr. Feldman also commented on the “substantial proportion” of patients lost to follow-up over the course of this study. Because of this, he observed, a sensitivity analysis would be required “to help substantiate their conclusions. So if you made the worst assumption and said that all those lost to follow-up did poorly, you might make the opposite conclusion.”

Ultimately, “their observation that there are very slow changes in some patients warrants one of their other conclusions: more study is needed,” he said, adding that it would need to be prospective in nature and separate the diseases and etiologies.

“Somewhere in the populations of patients with regurgitant lesions are patients who may progress very slowly, and it would be useful to identify them so we could stratify our follow-up more finely,” Dr. Feldman concluded. “Right now we have broad echo guidelines that say these patients should have… echos every 6 or 12 months. If we could say there [are] patients who really only need clinical follow-up maybe every other year, then that would be very helpful. The study suggests that we might be able to figure that out.”

Source:
Kusunose K, Cremer PC, Tsutsui RS, et al. Regurgitant volume informs rate of progressive cardiac dysfunction in asymptomatic patients with chronic aortic or mitral regurgitation. J Am Coll Cardiol Img. 2014;Epub ahead of print.

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