Using the CardioMEMS HF System for medication management of HF
Despite significant improvements in care, HF remains a progressive, complex disease process associated with significant hospital admissions and cost.
Upward of 25% of patients are readmitted to the hospital within 30 days of discharge, which contributes significantly to the $40 billion spent annually on HF in the United States. One of the most common reasons for readmission is signs and symptoms of congestion, which is often underrecognized in the outpatient setting.
Implantable systems for monitoring
Implantable systems for chronic monitoring of intracardiac and pulmonary artery pressure (PAP) provide noninvasive real-time information regarding volume status. Data indicate the PAP may increase up to 2 weeks before congestion symptoms, suggesting early recognition could allow appropriate correction before symptom onset.
The most commonly used wireless implantable hemodynamic monitoring device is the CardioMEMS HF System (Abbott), which has demonstrated significant improvements in patient outcomes and is typically managed by a HF cardiologist.
CardioMEMS is indicated for patients with NYHA class III HF who have experienced at least one HF-related hospitalization (HFrH) in the past 12 months. The CardioMEMS PA sensor is about the size of a paperclip and is typically placed via the femoral vein in the patient’s left descending PA. Implant typically occurs in a cardiac catheterization laboratory and patients are discharged the same day. Patients should be on aspirin 81 mg to 325 mg and clopidogrel 75 mg daily for 1 month after device placement. Patients with an indication for anticoagulation can remain on anticoagulation in place of clopidogrel.
Patients are given a pillow that they lay on, which contains a sensor to take the reading. Patients will usually take daily readings and these values are automatically transmitted to a secure website for review and intervention, when necessary, by the managing HF cardiologist.
After implant, baseline values for the pulmonary capillary wedge pressure (PCWP), right atrial pressure and PA diastolic (PAD) are established. The right atrial pressure and PCWP are compared to determine whether volume or vascular resistance are increasing PAPs, and the PCWP and PAD are compared to see if there is discordance, since they should typically be similar. Daily PAD values should be assessed during the first week to establish the initial PAD pressure threshold range (PADPTR) accounting for any discordance between PAD and PCWP. This should initially be set with a wide range of 10 mm Hg to avoid overdiuresis, and the highest reading will be the upper threshold value. During the optimization phase, trends will be utilized instead of individual values. Measurements should be checked two to three times weekly and consistently high values of 3 of more days should be acted on. Every 2 weeks, the PADPTR should be reestablished. Once patients are euvolemic, a new target PAD pressure goal should be set as well as the PADPTR. Goal-directed medical therapy (GDMT) should be titrated to maintain pressures at these goals.
The CardioMEMS HF System was approved by the FDA in 2014 based on data from the CHAMPION trial. In this trial, 270 patients with NYHA class III HF who had been hospitalized within the last year received the CardioMEMS device compared with 280 patients in the control group. Regardless of left ventricular ejection fraction, CardioMEMS was associated with a 28% reduction in 6-month HFrH with unpowered secondary outcomes showing lower risk for death, as well as first or cumulative HFrHs. Similar outcomes, as well as improvements in patient quality of life, have been observed in other U.S.- and European-based studies. An important additional finding is that that CardioMEMS leads to improved titration of GDMT even in patients who were previously on maximally tolerated doses.
Despite a higher initial cost of implant, an economic analysis showed that there was an average savings in HF-related cost of $7,433 per patient in the first 6 months after implant and $11,210 in the 12 months after implant.
The GUIDE-HF trial of approximately 3,600 patients is underway and will provide insight on whether CardioMEMS leads to a reduction in mortality in addition to HFrH. CardioMEMS is well tolerated, with most adverse events being procedure-related, with access site hematomas, or anticoagulation-related, with minor hemoptysis and epistaxis. Sensor failures are extremely uncommon in the studies, as are thromboembolic events secondary to the pressure sensor.
Treating the numbers: HFrEF
The 2021 Update to the 2017 American College of Cardiology Expert Consensus Decision Pathway for Optimization of Heart Failure Treatment now recommends all patients with newly diagnosed stage C HF with reduced EF be initiated on an angiotensin receptor-neprilysin inhibitor (ARNI)/angiotensin receptor blocker/ACE inhibitor and guideline-recommended beta-blocker titrated to maximally tolerated or target doses. Loop diuretics for symptom management should also be considered, followed by the addition of mineralocorticoid antagonists, SGLT2 inhibitors, hydralazine/isosorbide dinitrate and ivabradine (Corlanor, Amgen) in appropriate patients.
It is worth noting that sacubitril/valsartan (Entresto, Novartis) was not available during the CHAMPION trial. Neprilysin inhibitors have been shown to augment natriuresis and vasodilation through increased circulation of natriuretic peptides, but the impact of these actions on PAP has yet to be fully described. The updated guidelines suggest ARNIs should be used preferentially over ACE inhibitors and angiotensin receptor blockers when possible. Given the volume-altering capabilities of sacubitril/valsartan, conversion from an ACE inhibitor or angiotensin receptor blocker should only be made once volume and salt depletion have been corrected. Utilization of PAD numbers to help guide appropriate timing of conversion can be useful. As a general rule, converting to an ARNI should be avoided or done cautiously (with diuretic dose reduction) in patients whose PAD is below their PAD pressure threshold range.
Hypovolemia – PAD trending below PADPTR
If patients have a PAD trending below the pressure threshold range and are without signs or symptoms of congestion, a reduction in diuretic dosing should be strongly considered. For patients utilizing sequential nephron blockade with a loop and a thiazide diuretic, the thiazide agent should be preferentially discontinued. If the PAD does not improve, a 50% dose reduction in loop diuretic should be considered. If the patient has postural hypotension, vasodilator therapies (including hydralazine/nitrates) should be reduced or discontinued. GDMT should be continued without dose escalation. The dose of ACE inhibitors/angiotensin receptor blockers/ARNIs may be reduced if hypoperfusion is causing considerable kidney dysfunction. Conversion from an ACE inhibitor/angiotensin receptor blocker to sacubitril/valsartan should be avoided and initiation of an SGLT2 inhibitor should be postponed until the patient’s volume status has returned to baseline.
Example (see Table 1 below):
PAD goal: 16 mm Hg
PAD threshold: 12 mm Hg to 20 mm Hg
Hypervolemia – PAD trending above PADPTR
For PAD greater than 5 mm Hg to 10 mm Hg above threshold, adjustments to diuretic therapy and vasodilators should be considered. If the PAD increase is correlated to patient-reported congestion, a volume reduction strategy should include a doubling of the loop diuretic dose. Once the loop dose reaches 80 mg of furosemide (or equivalent), consider addition of a thiazide agent to further enhance diuresis. Additionally, switching to a higher-potency agent with better bioavailability (torsemide or bumetanide) may be beneficial. In cases of significant congestion with resistance to oral agents, IV loop diuretics may be required with close monitoring and follow-up.
Initiation and dose titration of GDMT should be considered in hypervolemic patients. Patients on an ACE inhibitor/angiotensin receptor blocker should consider switching to an ARNI to aid with additional diuresis. The addition of an SGLT2 inhibitor may also be beneficial and should be considered after conversion to an ARNI. SGLT2 inhibitors are believed to induce osmotic diuresis with increased interstitial fluid clearance, so empiric diuretic dose adjustments should be explored when initiating therapy (see chart below). Vasodilators may also be added to aid with diuresis in the presence of elevated systemic vascular resistance. The subsequent preload and afterload reduction will need to be monitored closely with appropriate dose adjustments for changes in BP and volume status.
Example (see Table 2 below):
PAD goal: 16 mm Hg
PAD threshold: 12 mm Hg to 20 mm Hg
Example (see Table 3 below):
PAD goal: 18 mm Hg
PAD threshold: 16 mm Hg to 22 mm Hg
Euvolemia – PAD within targeted hemodynamic range
For patients within their goal PAD range, effort should be made to ensure appropriate optimization of GDMT. ACE inhibitors/angiotensin receptor blockers should be switched to sacubitril/valsartan (as appropriate), SGLT2 inhibitors should be considered and beta-blockers may be escalated to achieve target doses. Close monitoring of heart rate and rhythm with the CardioMEMS device can assist with this dose escalation. If maximally tolerated beta-blocker doses are not obtaining a heart rate less than 70 bpm in normal sinus rhythm, the addition of ivabradine can also be considered.
Example (see Table 4 below):
PAD goal: 16 mm Hg
PAD threshold: 12 mm Hg to 20 mm Hg
When making adjustments for out-of-target PAD pressures, close monitoring should be performed with readings 2 to 3 days per week until PAD values stabilize. Once three PADs are consistently in range, readings may decrease to weekly for continued maintenance monitoring. Of note, if there is ever concern for poor perfusion, further evaluation should be considered, including invasive hemodynamic monitoring or inpatient admission.
The management of patients with HF with preserved EF is more challenging, as few therapies have shown significant impact on outcomes. A subgroup analysis of CHAMPION showed patients with EF of at least 40% had a significant reduction in HFrH and higher medication changes. Although no mortality benefits were observed, since there are few interventions that impact this subgroup, CardioMEMS should be considered in the management of these complex patients.
Patients with LV assist devices are another complex group with frequent HFrH. During the CHAMPION study, 15 patients with CardioMEMS and 12 controls received LVADs, which was investigated in a post hoc analysis. The patients with CardioMEMS had a shorter time to LVAD implant, better renal function at the time of LVAD placement, and more medication titrations since time of CardioMEMS implant; however, there was no difference in cardiac filling pressures pre-LVAD implant. After LVAD implant, patients with CardioMEMS had significantly greater reductions in PAP. Although this is a small sample size, these data are encouraging for the use of CardioMEMS to optimize patients with LVADs.
CardioMEMS is a promising new technology for HF practitioners. The noninvasive hemodynamic monitoring provides an opportunity for real-time volume optimization through medication adjustments and patient education. While diuretic therapy is a large component to volume management, practitioners should also take the opportunity to utilize CardioMEMS data to optimize GDMT.
The results of the GUIDE-HF trial will further inform the effects of CardioMEMS on achievement of optimal GDMT as well as mortality. With appropriate monitoring and management, CardioMEMS has the potential to truly enhance the care of patients with HFrEF.
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- For more information:
- Heidi Brink, PharmD, BCPS, BCCP, is clinical pharmacy coordinator, Cardiology/Pulmonology/Cardiothoracic Transplant, Nebraska Medicine.
- Sara Varnado, PharmD, BCPS, BCCP, is advanced clinical pharmacist, Cardiology-Heart Failure, Heart Transplant and MCS, Intermountain Healthcare.
- Sarah A. Spinler, PharmD, FCCP, FAHA, FASHP, AACC, BCPS (AQ Cardiology), is the Cardiology Today Pharmacology Consult column editor. She is professor and chair of the department of pharmacy practice in the School of Pharmacy and Pharmaceutical Sciences at Binghamton University. She can be reached at email@example.com.