All patients with symptomatic severe AS who underwent BAV were consecutively enrolled. The center's heart team assessed the indication for BAV.

Procedural indications were classified as: (1) bridge to recovery: refractory cardiogenic shock, pulmonary edema or congestive heart failure due to severe AS, including patients under invasive mechanical ventilation; (2) bridge to decision: patients in whom it was judged that LV systolic function might recover and clinical condition improve via BAV, enabling subsequent definitive treatment (TAVI or SAVR); and (3) bridge to non-cardiac surgery: patients in whom urgent non-cardiac surgery was needed but had a prohibitive risk due to untreated severe AS.

Baseline clinical, laboratory, echocardiographic, hemodynamic and procedural data were collected retrospectively through reviews of hospital records. Follow-up was performed through hospital outpatient consultations or telephone interview. Laboratory and echocardiographic assessment was repeated three to six months after the procedure. Data on mortality were obtained from the National Patient Registry.

BAV was performed under conscious sedation, with different balloon devices (Nucleus® and Loma Vista Medical®), by the standard retrograde technique and under rapid ventricular pacing. Regarding balloon diameter (which ranged from 20 to 25 mm), the choice was made according to the individual patient's characteristics. Some patients had already been assessed by cardiac computed tomography for TAVI, and so these measurements were used. In other cases, aortic valve diameter was measured by a combination of transthoracic echocardiogram (or, in ventilated patients, transesophageal echocardiogram) and fluoroscopic angiogram during the procedure. The access route was the right or left femoral artery (arterial sheaths ranging from 11 to 12F) and access site closure was performed in all cases using Perclose ProGlide™ (Abbott Vascular, Abbott Park, IL, USA) or Angio-Seal™ STS (St. Jude Medical, St. Paul, MN, USA) devices. An unfractionated heparin bolus was administered after sheath insertion (70-100 IU/kg).

The primary endpoint was the incidence of all-cause death during long-term follow-up. The secondary endpoint was the composite of cardiovascular or unknown cause death and rehospitalization due to heart failure, stroke, or myocardial infarction. Serious adverse events were defined as stroke, coronary occlusion or dissection, moderate to severe aortic regurgitation, tamponade, permanent pacemaker requirement and vascular complication requiring intervention. All events were retrospectively adjudicated according to the second Valve Academic Research Consortium (VARC-2) statement.10

The statistical analysis was performed with IBM SPSS Statistics for Windows, version 20.0. Continuous values are reported as mean±standard deviation or median (interquartile range [IQR]), and categorical data are reported as number and percentage. The Wilcoxon test was used to compare two dependent nonparametric variables. Kaplan-Meier survival analysis was performed. Cox regression was used to identify independent predictors of mortality.

Between January 2013 and January 2016, 23 patients underwent standalone BAV procedures, 56.5% male, mean age 78±7 years. A total of 40 patients were included, of whom 34.8% were in New York Heart Association functional class IV (n=8), and the remainder were in class III. Baseline pre-implantation characteristics are summarized in Table 1. The risk of mortality according to the Society of Thoracic Surgeons (STS) score was 12.3±10.0% (with a risk of morbidity or mortality of 47.0±18.8%), and mean EuroScore II was 11.7±6.0.

The main comorbidities were hypertension, coronary artery disease (CAD), dyslipidemia, atrial fibrillation (AF), diabetes, chronic kidney disease (CKD) (defined as Kidney Disease Outcomes Quality Initiative stage ≤3 [creatinine clearance <60 ml/min/1.73 m2]), chronic obstructive pulmonary disease (COPD) and malignancy (Table 1). A total of 26.9% of patients had previously undergone percutaneous coronary intervention (PCI) due to critical CAD.

Indications for BAV were bridge to recovery (n=5), including three patients under invasive mechanical ventilation; bridge to non-cardiac surgery (n=8); and bridge to decision (n=10).

The pre-procedure maximum and mean aortic gradients measured by transthoracic echocardiogram were 71.7±24 mmHg and 42.9±13.3 mmHg, respectively, with aortic valve area of 0.7±0.3 cm2 (0.4±0.1 cm2/m2). Mean left ventricular ejection fraction (LVEF) was 40.2±17.4%, and mean pulmonary artery systolic pressure (PASP) was 53.7±13.5 mmHg.

The procedure was performed under conscious sedation, by femoral access, with 11-12 F sheaths. The Nucleus® balloon was used in the majority of cases (n=18; 78.3%), and the Loma Vista Medical® balloon in the remainder (n=5; 21.7%), with a mean balloon size of 20.8±1.5 mm. Two cases (8.9%) required two inflations. Vascular closure devices were used in all patients; the Perclose ProGlide™ was used in 91.3% of cases and the Angio-Seal™ STS in the remainder. Mean procedure duration was 77.0±29.3 min. Mean fluoroscopy time was 16.6±7.4 min, with a fluoroscopic radiation dose of 59.3±28.5 μGy/cm2 and a contrast dose of 71.1±66.3 ml.

The peak gradient assessed invasively during the procedure decreased from a median of 54.0±19.0 mmHg to 28.5±13.8 mmHg (p=0.002) (Figure 1). Although without statistical significance, there was a trend for reductions in N-terminal pro-B-type natriuretic peptide (NT-proBNP) and PASP and improvement in LVEF during follow-up (NT-proBNP 4972±15401 pg/dl to 4654±8009 pg/dl, p=NS; PASP 53±18 mmHg to 39±11 mmHg, p=NS; LVEF 50±33% to 56±30%, p=NS).

Figure 1.

Peak transaortic gradient assessed invasively pre- and post-transcatheter aortic valve implantation.

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There were three serious adverse events in two patients. One patient experienced an ischemic stroke and left lower limb ischemia requiring urgent surgery, and another a femoral pseudoaneurysm requiring elective repair. No other complications occurred, including acute moderate or severe aortic regurgitation, or need for urgent permanent pacemaker implantation, SAVR or TAVI.

All patients under invasive mechanical ventilation (n=3) were extubated soon after the intervention and patients undergoing non-cardiac surgery had no major perioperative cardiovascular complications.

There was one BAV procedure-related death (4.3%) due to ischemic stroke and acute limb ischemia as procedural complications. Another patient had a right coronary artery rupture during PCI, and went into cardiogenic shock even after the rupture was resolved. He underwent BAV immediately, which resulted in some hemodynamic improvement, but eventually died in refractory cardiogenic shock. A third patient underwent a pre-TAVI left main PCI complicated by cardiogenic shock and BAV was performed successfully. Nevertheless, this patient also progressed to refractory cardiogenic shock and died. Overall in-hospital mortality was thus 13.0% (n=3).

During a mean follow-up of 258±303 days, 34.8% (n=8) of the patients underwent TAVI (mean time between BAV and TAVI 155.0±91.3 days) and 8.7% (n=2) underwent SAVR.

During follow-up, thirteen patients (56.5%) died, predominantly of non-cardiovascular causes (n=9, 69.2%), corresponding to the primary endpoint of all-cause death. These patients died on average 5.5 months after BAV (range 0-15 months, median three months). Five patients (21.7%) reached the secondary endpoint: four deaths of cardiovascular or unknown cause, and one readmission due to heart failure during follow-up. Readmission due to stroke or myocardial infarction did not occur.

On Kaplan-Meier analysis, mortality was significantly lower among patients undergoing TAVI or SAVR at one-year follow-up (10.0% vs. 61.5%; p=0.005) and at two-year follow-up (20.0% vs. 84.6%; p=0.005) (Figure 2). Only definitive treatment was a predictor of survival (TAVI – hazard ratio [HR]: 8.5, 95% confidence interval [CI]: 1.1-69.3, p=0.05; TAVI or SAVR – HR: 7.4, 95% CI: 1.5-37.2, p=0.02), by Cox regression analysis. Age, left ventricular function, comorbidities (hypertension, dyslipidemia, diabetes, CAD, AF, CKD, malignancy, CPOD, liver disease), BAV indication, STS score and EuroScore II were not predictors of survival following BAV.

Figure 2.

(A) Two-year Kaplan-Meier survival curves of patients undergoing TAVI after BAV vs. those maintained under medical therapy; (B) two-year Kaplan-Meier survival curves of patients undergoing TAVI or SAVR after BAV vs. those maintained under medical therapy. BAV: balloon aortic valvuloplasty; SAVR: surgical aortic valve replacement; TAVI: transcatheter aortic valve implantation.

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In light of our results and the limited availability of TAVI (since the prosthesis is not yet available off the shelf), we believe BAV should primarily be used as a bridge to definitive therapy (accepted or intended). This includes (1) patients who require non-cardiac procedures such as surgery or treatment for infection or cancer, (2) outpatients on a waiting list who are deteriorating clinically, and (3) inpatients with acute heart failure due to AS refractory to medical therapy (such as ventilated patients who cannot be weaned).

We believe BAV primarily for palliative purposes is generally not a good option, as these patients die shortly afterwards if no definitive treatment is undertaken, and essentially exposes patients to a procedure that is prone to complications but with no impact on prognosis. However, in some cases the patient's prognosis may not be absolutely clear. Thus, an individualized, multidisciplinary approach should be pursued.

Regarding timing, as our results and those of others clearly demonstrate, BAV provides an effective yet short-lived improvement, with a mean survival of 5.5 months and many patients dying within only three months. Thus, definitive treatment should ideally be offered as soon as possible and no later than three months after BAV, although we realize this may be difficult due to limited availability of prosthetic valves.

Our study has limitations, mainly related to its retrospective design, and to the assessment of complications according to the VARC-2 definitions, which have been described and updated specifically for TAVI patients. Echocardiographic follow-up was performed at the discretion of the attending clinicians rather than routinely, which may limit the value of comparisons of hemodynamic data from echocardiography.

The authors declare that no experiments were performed on humans or animals for this study.

The authors declare that they have followed the protocols of their work center on the publication of patient data.

The authors have obtained the written informed consent of the patients or subjects mentioned in the article. The corresponding author is in possession of this document.