Prognostic Impact of Pre-Existing Right Ventricular Dysfunction on the Outcome of Transcatheter Aortic Valve Implantation

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Abstract: Aims. Right ventricular dysfunction is a well recognized adverse prognostic factor in patients undergoing surgical aortic valve replacement. The prognostic significance of right ventricular dysfunction in the context of transcatheter aortic valve implantation (TAVI) has not been established. We evaluated the relationship between preprocedural right ventricular impairment and the outcome of TAVI. Methods and Results. Between December 2007 and December 2011, a total of 155 patients with severe aortic stenosis underwent TAVI at the Sussex Cardiac Centre, of whom 83%-91% had prospective analysis of right ventricular function prior to TAVI using two different standard echocardiographic methods. We identified patients with preserved and impaired ventricular function and compared their all-cause mortality during follow-up. Right ventricular dysfunction was defined as tricuspid annular plane systolic excursion (TAPSE) <15 mm or right ventricular peak systolic velocity (RVPSV) <9 cm/s and was identified in 11% of patients. Vital status was established from the Office of National Statistics. Average follow-up was 628 ± 392 days. A total of 107 patients were followed for at least 1 year and 63 patients for at least 2 years. Cumulative total mortality was 17.4%. In-hospital mortality was 2.6%, death within 30 days was 5.8%, 1-year mortality was 14.0%, and 2-year mortality was 15.9%. There was no statistically significant difference in outcome between patients with and without right ventricular dysfunction. This finding was consistent between the two methods used to determine right ventricular function (TAPSE: hazard ratio [HR] 1.57 and P=.42;  RVPSV: HR 1.28 and P=.71). Conclusions. Preprocedural right ventricular dysfunction does not adversely impair immediate or follow-up survival during medium-term follow-up after TAVI.

J INVASIVE CARDIOL 2013;25(3):142-145

Key words: right ventricle, valvular heart disease, complications

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Transcatheter aortic valve implantation (TAVI) has been a major step forward in the management of severe aortic stenosis. Initially reserved exclusively for non-operable patients, the spectrum of patients indicated for this percutaneous procedure is widening. Based on the results of the PARTNER A trial, TAVI is now considered to be a reasonable alternative to surgical aortic valve replacement (AVR) in patients at high surgical risk (STS >8%) as stated in the recently published 2012 ACCF/AATS/SCAI/STS expert document on transcatheter aortic valve replacement.^1,2 With growing experience in the field of TAVI, there is likely to be a gradual move to treatment of lower-risk groups over time.^3,4

Identification of prognostic indicators for TAVI, and their comparison with traditional risk factors for surgical aortic valve replacement (AVR), is therefore important. There is no TAVI standardized risk predicting model comparable to the surgical Euroscore; however, several clinical and procedural characteristics have been shown to impact on outcome after TAVI. Baseline cardiovascular characteristics (low left ventricular ejection fraction, moderate-to-severe mitral regurgitation) and periprocedural complications (tamponade, vascular complications, moderate-to-severe residual aortic regurgitation) seem to play a role in acute and early mortality, while non-cardiac comorbidities (chronic obstructive pulmonary disease, liver disease, chronic kidney disease) impact on long-term mortality.^5-9 

Pulmonary hypertension is an accepted predictor of poor outcome after surgical AVR, and there is growing evidence that tricuspid regurgitation and pulmonary hypertension have an adverse impact on prognosis for patients undergoing TAVI.^6,7,10 Data suggest that perioperative morbidity and mortality associated with pulmonary hypertension (PH) are dependent on right ventricular (RV) adaptation to high pulmonary vascular resistance rather than on the absolute value of pulmonary artery pressure (PAP).¹¹ Cardiotomy results in depression of RV function postoperatively, while TAVI may leave RV function unchanged.¹²

Data on the prognostic significance of RV dysfunction in the context of TAVI are lacking. We therefore examined the relationship between preprocedural RV function and outcome of patients undergoing TAVI. 

Methods

Study population. We analyzed a cohort of 155 patients with symptomatic severe aortic stenosis who underwent elective TAVI in our center between December 2007 and December 2011. Echocardiographic parameters of preprocedural RV function were prospectively obtained as a part of routine evaluation prior to TAVI. Patients were stratified according to presence or absence of RV systolic dysfunction. Outcomes between the groups were compared during follow-up. Patient survival was tracked using the Office of National Statistics Central Register. 

Echocardiography. Doppler color echocardiography was performed using a GE Vivid 7 console. Right ventricular function was assessed using: (1) tricuspid annular plane systolic excursion (TAPSE) measured by M-mode in the transapical four chamber view; and (2) right ventricular peak systolic velocity (RVPSV) of the tricuspid annulus measured by tissue Doppler in the same view. Both parameters (TAPSE and RVPSV) have been previously shown to correlate well with radionuclide-derived right ventricular ejection fraction (RVEF) and are considered to be straightforward and reproducible measurements.¹³ RV systolic dysfunction was defined as TAPSE <15 mm or RVPSV <9 cm/s.¹⁴

TAVI. Implantation procedures were performed by a dedicated team of experienced operators under fluoroscopic guidance in a cardiac catheterization laboratory. The approaches used were femoral (87.1%), subclavian (7.1%), transapical (3.2%), or direct aortic (2.6%). Transfemoral procedures were performed under anesthetic sedation using low-dose titrated propofol/remifentanyl. General anesthesia was reserved for non-transfemoral cases. The self-expanding CoreValve Revalving System (CRS; Medtronic Inc) was used in 96.8% of cases, the Edwards SAPIEN valve (Edwards Lifesciences) in 3.2%.  

Statistical analysis. Continuous variables are expressed as mean ± standard deviation and were analyzed with the student’s t-test. Categorical variables are presented as frequency (percentages) and were compared using the Pearson Chi-square test or Fisher’s exact test. Survival curves were constructed using Kaplan-Meier estimates. A Cox multivariable regression analysis was used to determine mortality predictive factors. A two-sided P<.05 was considered to indicate significance. All statistical analyses were performed with SPSS software (SPSS Inc). 

Results

Baseline clinical and procedural characteristics are summarized in Table 1. Patients were aged 81.5 ± 6.2 years, with equal sex distribution. One-quarter were diabetic and two-thirds had a history of coronary artery disease. Nearly 20% of the patients had moderate-to-severe impairment of left ventricular systolic function. Half of the cohort had raised pulmonary artery pressures (sPAP >35 mm Hg). Around 20% of the patients had moderate-to-severe PH (sPAP >45 mm Hg) or moderate-to-severe tricuspid regurgitation. With regard to RV dysfunction, this was noted in 10.3% using RVPSV and 11.6% using TAPSE. Baseline characteristics did not differ between the two groups, with the exception of age — patients with RV dysfunction were younger than those with normal RV function (Table 2). 

Average follow-up was 628 ± 392  days. A total of 107 patients were followed for at least 1 year and 63 patients for at least 2 years. Cumulative total mortality was 17.4%. Cumulative mortality of the patients with RV dysfunction was 20.5%; patients with preserved RV function had mortality of 13.9%. Total in-hospital mortality was 2.6%, early mortality (defined as death within 30 days) was 5.8%, 1-year mortality was 14.0%, and 2-year mortality was 15.9%. 

RV dysfunction was not shown to be an independent predictor of adverse outcome after TAVI. This finding was consistent between the two methods used to determine RV function. When evaluated either by TAPSE (hazard ratio [HR] 1.57; 95% confidence interval [CI], 0.52-4.82; P=.42) or RVPSV (HR 1.28; 95% CI, 0.35-4.68; P=.71), RV dysfunction did not appear to confer an adverse prognostic significance during medium-term follow-up.

Discussion 

This study suggests that preprocedural RV dysfunction does not adversely influence medium-term outcome following TAVI. These data contrast with those following surgical aortic valve replacement, which demonstrate impaired RV function to be a strong independent predictor of perioperative complications and late mortality (Figures 1 and 2).^15,16

A number of factors may adversely influence RV function during and following cardiothoracic surgery. These include prolonged cardiopulmonary bypass times, inadequate cardioprotection, right coronary air embolism, loss of atrioventricular synchrony, and reperfusion lung injury increasing pulmonary artery pressures.¹¹ As a result, preprocedural impairment of RV function may render the cardiac surgery patient susceptible to poor outcomes.

TAVI, however, spares the patient most of these adverse effects on contractile function and indeed, it has been shown that there is no depression of RV systolic function after TAVI procedures.¹² While hypotension and RV ischemia are not uncommon during TAVI, these features are usually short-lived and have only a temporary effect on RV function. Recovery is swift, in the absence of a major complication such as right coronary artery occlusion, which is rare. 

RV dysfunction, therefore, is a factor that tends to deter surgeons from accepting patients for aortic valve surgery. This may explain why the average age in our cohort of patients undergoing TAVI was lower among patients with known RV dysfunction. 

Our study provides preliminary data to suggest that impairment of RV systolic function should be taken into account by multidisciplinary teams when deciding between the options of surgical aortic valve replacement and TAVI.

Conclusions. Preprocedural RV dysfunction does not seem to adversely impair immediate or follow-up survival during medium-term follow-up after TAVI.

Study imitations. This study concerned prospectively gathered data from a single-center experience only and is therefore limited in size. As a result, only a relatively small number of patients in the study had impairment of RV function. Our findings should therefore be considered exploratory and hypothesis-generating. Larger studies are required to confirm or refute the findings. 

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From the Sussex Cardiac Centre, Brighton and Sussex University Hospitals, East Sussex, United Kingdom.

Disclosure: The authors have completed and returned the ICMJE Form for Disclosure of Potential Conflicts of Interest. Dr Hildick-Smith is a consultant for CoreValve, Inc. The authors report no conflicts of interest regarding the content herein.

Manuscript submitted October 21, 2012, provisional acceptance given December 4, 2012, final version accepted January 7, 2013.

Address for correspondence: Sussex Cardiac Centre, Brighton and Sussex University Hospitals, Eastern Road, BN2 5BE, Brighton, East Sussex, UK. Email: petra.poliacikova@bsuh.nhs.uk