Clinical Editor's Corner: Kern

The “Big 5”: Avoiding the Most Dangerous Complications of TAVR

Morton J. Kern, MD

Morton J. Kern, MD

[Full disclosure: I am not performing TAVR procedures, but I do follow the advances in the field, procedure risks, benefits, and complications as presented in the literature, at meetings, conferences, and colleagues’ personal communications. ­— MK]

Structural interventionalists have successfully extended the application of the transcatheter aortic valve replacement (TAVR) technique from the high-risk populations to both intermediate- and low-risk aortic stenosis patients. Quality outcomes and survival data continues to accumulate in support of this dramatic cardiac procedure, probably the most important since the development of coronary stenting. In recognition of the safety of TAVR, the Centers for Medicare and Medicaid Services just removed the two-surgeon requirement and relaxed volume requirements for TAVR programs. Approval for TAVR in low-risk patients appears imminent given its superior outcomes compared with surgical aortic valve replacement (SAVR).

Thousands of patients have been helped by TAVR. On a personal level, I can attest to the great benefit that TAVR provided to my 90-year-old mother.1 There is little doubt that TAVR will become routine at many interventional laboratories over the coming years, just as complex percutaneous coronary intervention (PCI) has become increasingly routine. With continued attention to technique and patient selection, the successful performance of TAVR will evolve as another safe and straightforward interventional procedure. However, on the way to this goal, operators must be vigilant and cognizant of complications that can be avoided.

The “Big 5” Complications

I recently came across a review of the impact of complications on TAVR mortality by Arnold et al2, as well as a wonderful editorial by Eberhard Grube and Jan-Malte Sinning3, aptly titled to highlight which of the many complications have the biggest impact on mortality: “The Big Five Complications After Transcatheter Aortic Valve Replacement: Do We Still Have to Be Afraid of Them?”

TAVR Complications and 30-Day Survival

Arnold et al2 reviewed 3763 TAVR patients who had intermediate or high surgical risk TAVR procedures as part of the PARTNER II studies and survived 30 days. Complications within the initial 30-day period that particularly affected mortality and quality of life were examined. Assessed complications included major/minor stroke, life-threatening and major bleeding, vascular injury, Stage 3 kidney disease, new pacemaker implantation, and perivalvular leak (Table 1). In the study population, major stroke and Stage 3 kidney disease were associated with highest risk for one-year mortality, with adjusted hazard ratios of 5.4 and 4.9, respectively. These two complications were also associated with a poor quality of life among the survivors, with reductions in one-year Kansas City Cardiomyopathy Questionnaire scores. Importantly, perivalvular leak (both moderate and severe grades) and life-threatening major bleeding were each associated with a more modest increase in mortality and decrease in quality of life, whereas mild perivalvular leak was associated with only a small decrease in quality of life. The editorial by Drs. Grube and Sinning identifies the “Big 5” complications (Figure 1), and points out that an event-free TAVR procedure without the occurrence or recurrence of any of the Big 5 complications has the lowest morbidity and mortality.

Contributions of Perivalvular Leak, Minor Stroke, and Pacemaker to TAVR Mortality

After adjustments for baseline characteristics and other complications2, need for a pacemaker, minor stroke, and vascular injury were not independently associated with poor outcomes. Arnold et al’s analysis concluded that the major complications (Tables 1-2, Figure 1) are significantly linked with increased mortality and impaired quality of life in TAVR patients. Despite considerable technical and clinical progress, operators and TAVR teams should make every effort to protect against stroke, acute kidney injury, and bleeding. Treatment of moderate or severe perivalvular leak is also likely to provide important clinical benefits.

Why the “Big 5”?

As we learn in the editorial3, the Big 5 designation comes from big-game hunters in Africa, referring to the most dangerous 5 animals to encounter while hunting on foot. Sighting (encountering a complication) any of the Big 5 can lead to death of the hunter or members of the hunting party, and extra precautions are needed for such encounters. The same can be said about TAVR’s Big 5 complications, which are to be prevented by all means possible during the procedure. There is consistency within the literature regarding the impact of complications for both PCI and TAVR. Each of the Big 5, whether occurring alone or in combination, will contribute to mortality; the weight of each complication varies by the timing of the complication and the particular patient. Nonetheless, although the risks of TAVR complications may vary within each of the high-, intermediate-, and low-risk subgroups, the Big 5 have an associated importance to outcomes across all groups. From experience, we know that some of the complications may be better tolerated in a low-risk group compared to high-risk, ultra-elderly patients.

Perivalvular Leak, Bleeding, and TAVR Mortality

It is somewhat remarkable that a cylindrical, stented valve cage implanted in the dilated native aortic root and calcified valve annulus would occur without some degree of perivalvular leak. Unfortunately, the ability to predict perivalvular leaks is poor even with advanced imaging by both ultrasound and computed tomography (CT). The latest generations of TAVR catheter systems include external sealing skirts that can reduce perivalvular leak by occluding the leak or promoting thrombosis of the peri-prosthetic valve spaces. Lower degrees of perivalvular leak produce better clinical outcomes, as noted.2 Further advances in TAVR catheter delivery systems will also permit the adjustment of valve positioning after the valve is fully deployed, something which may further reduce the degree of perivalvular leak.

Vascular injury with bleeding is an uncommon but accepted complication, given the predominately older patients in the intermediate- and high-risk TAVR groups. Choosing the best access site for a particular patient requires pre-procedural imaging to assess vascular calcification and vessel tortuosity to reduce vascular injury and bleeding. Ultrasound guidance has increasingly been shown to reduce vascular complications in the TAVR population. On the technical front, smaller diameter next-generation devices with lower profiles, and sheaths that can expand after insertion and contract after catheter removal to limit arterial puncture size will emerge to reduce bleeding complications. Lastly, much attention has been given to vascular access closure techniques, particularly for large-bore access issues.4

Need for a Pacemaker and Poor TAVR Outcomes

New conduction disturbances induced by TAVR, although markedly less frequent with more recent devices, is still a persistent problem and if untreated, poses a threat for patients who could develop sudden complete heart block. A tradeoff between oversizing the TAVR prosthesis to achieve lesser degrees of perivalvular leak must be balanced against forceful compression of conduction tissue under the valve and inducing conduction abnormalities requiring a pacemaker. Fortunately, post-procedural pacemaker implantation had only a small effect on survival or quality of life after adjusting for pre and periprocedural patient characteristics.2

Impact of Early vs Late TAVR-Related Stroke

Post-procedure stroke is the most concerning complication of the Big 5, perhaps more feared than death by some of our elderly patients. The TAVR-related stroke risk is lower than that found for SAVR and is reported to occur in about 2% of TAVR procedures.5,6 Because of the impact on outcomes, we should differentiate the two most common stroke mechanisms. Periprocedural embolic stroke occurs during the first 48 hours and accounts for about half of the TAVR-related strokes. Occult atrial fibrillation or subclinical valve thrombosis associated with emboli and ischemic stroke account for the other 50% of cerebrovascular accidents. To reduce the consequences of this complication of Big 5, several approaches have been developed, including the use of cerebral protection devices, better intraprocedural anticoagulation, and post procedural antiplatelet and anticoagulants (balancing post-procedure bleeding and thromboembolic events).

Hemodynamic Complications

Although not as critical as the Big 5, hemodynamic complications of TAVR include residual aortic stenosis, subvalvular hypercontractile hypertrophic obstructive cardiomyopathy-like obstruction, acute aortic regurgitation, aortic dissection, ascending aortic dissection including root with mitral regurgitation (MR), coronary occlusion, left ventricular (LV) perforation, and tamponade (Figure 2). Kalra et al7 described echocardiographic and hemodynamic correlates of the hemodynamic complications of TAVR and their management. Figure 3, courtesy of Dr. Raj Makkar, demonstrates transcatheter hemodynamics before (Panel A[i]) and after (Panel A[ii]) TAVR (with heart block-related bradycardia). There is significant aortic regurgitation immediately following TAVR. Within minutes following right ventricular pacing (Panel C[iii]), aortic regurgitation is reduced with resolution of rapid filling over diastasis, increased diastolic pressure and end-diastolic LV–Ao gradient, and drop in left ventricular end diastolic pressure (LVEDP), demonstrating the reduction in significant aortic regurgitation. Peri-TAVR color-flow Doppler in the long-axis and short-axis views (Panels B and C, respectively), and pulse wave Doppler (panel D) echocardiography, all demonstrate varying degrees of aortic regurgitation following rapid right ventricular pacing, which restored near-normal hemodynamics. (The use of hemodynamics for TAVR will be more fully discussed in a future editor’s page.)

The Bottom Line

We should be aware of the Big 5 complications of TAVR and do everything possible to avoid these feared events. For the moment, observing intraprocedural hemodynamic changes can serve as an early warning light of an impending problem. Hopefully, it won’t be one of the Big 5. 

Disclosures: Dr. Morton Kern reports he is a consultant for Abiomed, Abbott Vascular, Philips Volcano, ACIST Medical, Opsens Inc., and Heartflow Inc.

References
  1. Kern M. TAVR — a personal experience. Cath Lab Digest. 2013 June; 21(6): 4-8. Available online at https://www.cathlabdigest.com/articles/TAVR-%E2%80%93-Personal-Experience. Accessed August 12, 2019.
  2. Arnold SV, Yiran Zhang Y, Baron SJ, et al. The Impact of short-term complications on mortality and quality of life after TAVR. JACC Cardiovasc Interv. 2019 Feb 25; 12(4): 362-369.
  3. Grube E, Sinning JM. The big five complications after transcatheter aortic valve replacement: Do we still have to be afraid of them? JACC Cardiovasc Interv. 2019 Feb 25; 12(4): 370-372.
  4. Cheney AE, McCabe JM. Alternative percutaneous access for large bore devices. Circ Cardiovasc Interv. 2019 Jun; 12(6): e007707.
  5. Grube E, Van Mieghem NM, Bleiziffer S, et al; FORWARD Study Investigators. Clinical outcomes with a repositionable self-expanding transcatheter aortic valve prosthesis: the international FORWARD study. J Am Coll Cardiol. 2017 Aug 15; 70(7): 845-853.
  6. Thourani VH, Kodali SK, Makkar RR, et al. Articles Transcatheter aortic valve replacement versus surgical valve replacement in intermediate risk patients: a propensity score analysis. Lancet. 2016; 387: 2218-2225.
  7. Kalra A, Makkar RR, Bhatt DL, et al. Transcatheter and Doppler waveform correlation in transcatheter aortic valve replacement. Open Heart. 2018;0:e000728. doi:10.1136/openhrt-2017-000728