Impaired RV Reserve Predicts Cardiac Outcomes in Congenital Heart Patients
- Impaired right ventricular (RV) reserve may occur in adult patients with congenital heart disease who have normal resting right ventricular function. RV reserve impairment can precede the development of overt signs of cardiac dysfunction on resting imaging
- Among the patients in this population with impaired exercise RV reserve during exercise testing, many (32%) were asymptomatic
- Impaired RV reserve independently predicts adverse cardiac outcomes, such as arrhythmia and heart failure in this population
- The incidence rate of poor cardiac outcomes, including heart failure or death, was far greater in adult patients with congenital heart disease with severe RV reserve (48%) compared to patients with mild to moderate reserve impairment (24%) or normal RV reserve (9%)
- Close to half (46%) of 50 adult patients with congenital right heart disease had abnormal reserve, and yet they also had normal right ventricular ejection fraction at rest and a favorable peak VO2 =20 mL/kg/min
Adults with congenital heart disease (CHD) often have right ventricular (RV) failure that typically goes unrecognized. Clinicians are continually looking for new ways to detect early RV dysfunction. Previous research has shown that impaired RV exercise reserve using radionuclide imaging (RNI) can predict heart failure outcomes in people with non-congenital systolic left heart failure.
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To better understand RV exercise reserve and its potential as a predictive measure, Doreen DeFaria Yeh, MD, associate director of the Mass General Adult Congenital Disease Program, and colleagues from the Adult Congenital Heart Disease Program at Massachusetts General Hospital conducted a study to assess its relationship to cardiac outcomes.Following multivariate analysis, they concluded in Heart that RV reserve impairment independently predicts adverse cardiac outcomes in adults with congenital right heart disease.
In this retrospective, single-center study, the team evaluated adult CHD patients who underwent CPET from January 2011 to December 2014 at Mass General. Data evaluated included demographic, medical, cardiac magnetic resonance imaging (MRI) and transthoracic echocardiography (TTE). They evaluated RV reserve in the context of other variables known to be predictive of adverse cardiac outcomes in this population including resting RV dilation and dysfunction, quick response system duration and peak VO2.
Patients were stratified by RV reserve. A score was created to combine measures of dynamic exercise systolic function, including peak exercise RV systolic function and change in right ventricular ejection fraction (RVEF) from rest to peak exercise. A score of 0 (normal exercise reserve) was defined by normal peak exercise ventricular function >45% and augmentation of ≥5% with exercise or exercise RVEF >50%. Scores >0 indicated impaired RV reserve, with 1–3 being called mild to moderate and 4–5 as severe impairment. The primary outcome was a composite of clinical heart failure, arrhythmia, cardiac transplantation and death.
After multivariate analysis, the team found RV reserve was an independent predictor of the primary outcome: "After multivariate analysis, the team found RV reserve was an independent predictor of the primary outcome. Specifically they found:
- Patients with severe impaired RV reserve had a 48% incidence rate for poor cardiac outcomes, including heart failure and death
- Patients with moderate or mild impaired RV reserve had a 24% incidence rate
- Patients with normal reserve had a 9% incidence rate
The researchers found that abnormal RV reserve often occurred among asymptomatic patients (32%) and importantly 52% of patients with severely impaired RV reserve had qualitatively normal resting RV systolic function by echocardiography. This suggests that exercise unmasks early RV dysfunction among some patients with normal function at rest.
Notably, the team identified a subset of 50 patients, all with impaired RV reserve, who had a relatively favorable peak VO2 (≥20 mL/kg/min) and yet developed an adverse outcome.
Observing this result and others in the study, the team concluded that RV reserve may play a role in identifying adults with congenital right heart disease who have dynamic abnormalities in ventricular function and may benefit from intervention prior to a significant reduction in exercise capacity and the onset of resting RV dysfunction.
As such, RV reserve is a helpful predictive measure for outcomes such as arrhythmia and heart failure. Specifically, it could aid in stratifying patients into disease risk and individualize treatment plans.
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