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Interventional Heart Failure


Key Points

  • Despite current guideline-directed drug and electrophysiologic device therapies, many heart failure patients remain highly symptomatic, and outcomes remain poor. New therapies are needed to improve patients’ clinical status and outcomes.

  • Several causes of heart failure are amenable to interventional device-based therapies, an observation that led to emergence of the field of interventional heart failure.

  • Interventional heart failure targets include primary or secondary valve disease, left ventricular dilation or pathophysiologic remodeling, elevated left atrial and pulmonary artery pressures, and reduced cardiac output.

  • Interventions include transcatheter aortic valve replacement (TAVR), percutaneous mitral valve repair, percutaneous or hybrid ventricular partitioning or restoration, interatrial shunt devices, and implantable hemodynamic monitors.

  • With the exception of TAVR, percutaneous mitral valve repair (e.g., MitraClip system), and pulmonary artery pressure monitoring (e.g., CardioMEMS system), most devices remain under investigation for use in heart failure patients.

  • Severe aortic stenosis is a potentially reversible cause of heart failure. TAVR improves symptoms and prolongs survival of patients with heart failure and severe aortic stenosis at intermediate and higher surgical risk.

  • Functional mitral regurgitation contributes to the vicious cycle of progressive heart failure, and preliminary findings for several percutaneous approaches to mitral valve repair and replacement are encouraging.

  • Pathologic left ventricular remodeling after anterior myocardial infarction leads to progressive heart failure. Percutaneous or hybrid ventricular partitioning or reconstruction devices aim to restore a more normal elliptical left ventricular geometry and reduce ventricular volume, reducing end-diastolic pressure, and improving symptoms and outcomes.

  • Elevated left atrial and pulmonary artery pressures increase the risk of heart failure, and interatrial shunt devices can lower left atrial pressure and improve hemodynamics and symptoms in systolic and diastolic heart failure patients.

  • Implantable hemodynamic monitors can guide changes in pharmacologic therapies to accomplish reductions in left atrial and pulmonary artery pressures, reducing the incidence of heart failure hospitalizations.

  • Convergence between the fields of interventional cardiology and heart failure is needed to guide the application of therapies for these patients.

Introduction

Heart failure is a growing public health problem. An estimated 5.1 million Americans have heart failure, and 825,000 new cases are diagnosed each year in the United States. By the year 2030, the U.S. prevalence of heart failure is expected to exceed 8 million people. Beyond these numbers, heart failure imposes an enormous burden on patients, caregivers, and the health care system.

New approaches are needed to improve the clinical status and outcomes of heart failure patients. Despite current drug and electrophysiologic device therapies, many patients have moderate to severe symptoms, a poor quality of life, and substantial limitations in exercise capacity. They are also at considerable risk for heart failure–related morbidity (e.g., hospitalization) and mortality. Heart failure is the primary diagnosis in more than 1 million hospital admissions annually in the United States. It is also associated with the highest rate of hospital readmissions compared with all other medical and surgical causes of hospitalization. In 2012, due in large measure to the high rates of hospitalization and rehospitalization, the U.S. total economic burden from heart failure was estimated at $31 billion.

The convergence of the fields of heart failure and interventional cardiology has produced a discipline called interventional heart failure . Although the term may be applied to virtually any invasive procedure performed in heart failure patients (e.g., diagnostic coronary angiography, percutaneous coronary intervention, invasive assessment of hemodynamics), it is more commonly reserved for the application of invasive therapeutic procedures intended to improve the clinical status and outcomes of heart failure patients.

Interventions usually target primary or secondary valve disease, left ventricular dilation or pathophysiologic remodeling, elevated left atrial and pulmonary artery pressures, or reduced cardiac output to improve cardiac structure, function, and hemodynamics. Myocardial ischemia is excluded from this list of interventional heart failure targets because coronary revascularization has not proved a beneficial heart failure therapy, although it may be useful for the treatment of symptomatic angina in heart failure patients.

Interventional heart failure procedures and devices include transcatheter aortic valve replacement (TAVR), percutaneous mitral valve repair (i.e., MitraClip percutaneous therapy), percutaneous or hybrid ventricular partitioning or restoration, interatrial shunt devices, and implantable hemodynamic monitors. With the exception of TAVR, MitraClip, and pulmonary artery pressure monitoring with the CardioMEMS heart failure system, most interventional heart failure devices remain under investigation in heart failure patients.

At least one form of neuromodulation (i.e., renal denervation) may be considered an interventional heart failure procedure when applied to the treatment of these patients, but it is not discussed in this chapter. Other forms of neuromodulation, including baroreflex activation therapy, vagal nerve stimulation, spinal cord stimulation, and phrenic nerve stimulation, involve the implantation of pulse stimulators and stimulation leads, and they are considered to be surgical or electrophysiologic interventions.

Transcatheter Aortic Valve Replacement

Heart failure in patients with aortic stenosis carries a grave prognosis. If the aortic valve is not replaced, patients with heart failure due to aortic stenosis have a 2-year mortality rate of 50%. In the setting of aortic stenosis, heart failure results from left ventricular hypertrophy with diastolic dysfunction or left ventricular dilation with systolic dysfunction, or both. Because heart failure results from the excess afterload caused by aortic stenosis, aortic valve replacement often leads to symptom improvement and a favorable outcomes, especially when the preoperative gradient across the aortic valve is high or a good contractile reserve has been demonstrated when the gradient is low.

Aortic valve replacement is recommended in patients with severe aortic stenosis and symptomatic heart failure with an aortic velocity of 4.0 m/s or greater or a mean pressure gradient of 40 mm Hg or higher. In asymptomatic patients, valve replacement is indicated when the left ventricular ejection fraction (LVEF) is less than 50%. In patients with an LVEF less than 50%, a calculated valve area less than 1.0 cm 2 but not meeting velocity or gradient criteria, low-flow, low-gradient severe aortic stenosis must be suspected. In these patients, a low-dose dobutamine stress study should be performed. If the study shows an aortic velocity of 4.0 m/s or greater, or a mean pressure gradient of 40 mm Hg or higher at any dobutamine dose, aortic valve replacement is recommended. Few data are available regarding TAVR for patients with low surgical risk and patients with bicuspid aortic valves. Therefore, surgical aortic valve replacement is currently recommended for these patient subgroups. Surgical aortic valve replacement in patients with a reduced LVEF can significantly improve or normalize the LVEF and improve survival.

An alternative to surgical aortic valve replacement in patients at intermediate or higher surgical risk is TAVR. The Placement of Aortic Transcatheter Valves (PARTNER) trial compared TAVR with standard therapy in high-risk patients with severe aortic stenosis and cardiac symptoms, including a cohort of patients who were not considered to be suitable candidates for surgery (i.e., Cohort B). Of the patients randomized in Cohort B, 93% exhibited New York Heart Association (NYHA) class III or IV symptoms at baseline, compatible with an advanced degree of heart failure. TAVR significantly improved the NYHA class ranking compared with ongoing medical therapy alone. In this cohort, there was a statistically significant 45% reduction in death from any cause for patients treated with TAVR compared with medically treated patients. These benefits were sustained at 2 years.

Data from PARTNER Cohort A (i.e., TAVR vs. surgical aortic valve replacement) demonstrated significant improvement in LVEF with TAVR (from 35.7 ± 8.5% to 48.6 ± 11.3%, P < .0001), comparable to that seen with surgical aortic valve replacement. In addition, mortality did not differ between those assigned to TAVR compared with surgical valve replacement through 5 years of follow-up.

These observations were extended in intermediate surgical risk groups in two large trials, PARTNER II (employing the Edwards SAPIEN valve) and Safety and Efficacy Study of the Medtronic CoreValve System in the Treatment of Severe, Symptomatic Aortic Stenosis in Intermediate Risk Subjects Who Need Aortic Valve Replacement (SURTAVI) (Medtronic CoreValve). These trials established comparable mortality and improvements in quality of life in patients with severe aortic stenosis undergoing surgical and TAVR. A consistent finding across all contemporary TAVR trials is a higher rate of pacemaker implantation, and greater residual paravalvular leak than that observed with surgical valve replacement. However, as technical experience, procedural efficiencies, and device improvements are realized, these rates have declined, and the ancillary benefits of TAVR (shorter length of stay, cost) may eventually make this approach standard of care.

Today, TAVR is a reasonable option for the treatment of symptomatic heart failure in patients with severe aortic stenosis at intermediate or higher surgical risk. The Edwards SAPIEN and Medtronic CoreValve are TAVR devices with U.S. Food and Drug Administration (FDA) approval. Numerous alternative TAVR devices are under investigation. In addition, as the procedural risks from TAVR continue to decline, additional populations that may benefit are being evaluated. Among these are patients with severe symptomatic aortic stenosis and low surgical risk scores, as well as patients with moderate aortic stenosis and symptoms of heart failure. These trials will collectively inform the management of aortic stenosis across the risk and severity spectrum, and stand to considerably change the approach to aortic valve disease in large populations.

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