Ischemic Cerebrovascular Complications of Cardiac Procedures

Extracranial carotid artery stenosis and outcomes of patients undergoing transcatheter aortic valve replacement

BACKGROUND

Transcatheter aortic valve replacement (TAVR) is an alternative to open cardiac surgery in selected patients with severe aortic stenosis (AS). Carotid artery stenosis (CAS) has been associated with an increased risk of stroke following cardiac surgery, although the association between CAS and outcomes following TAVR is unclear. We therefore sought to study the prognostic impact of CAS on outcomes of patients undergoing TAVR.

METHODS

Consecutive patients (n=312) with severe symptomatic AS who underwent a carotid Doppler study immediately prior to TAVR were followed prospectively. Major adverse cardiovascular event (MACE) rates were stratified by the presence of CAS, defined in accordance with current practice guidelines.

RESULTS

Carotid atherosclerosis (CA, defined as any carotid plaque) was present in 301 (96.5%) of patients and CAS (peak systolic velocity [PSV]≥125cm/s; ≥50% diameter stenosis) in 97 (31.1%) patients. Severe CAS (PSV≥230cm/s; ≥70% stenosis, or near occlusion) was found in 20 (6.4%) patients. At long-term follow-up (248±205days), composite (20.9% vs. 19.6%, p=0.50) and individual (all-cause mortality, stroke, myocardial infarction, readmission for heart failure [19.5%% vs. 14.4%%, p=0.24; 3.3% vs. 2.1%, p=0.47; 1.4% vs. 0%, p=0.22; and 7.9% vs. 8.2%, p=0.84 respectively]) MACE rates did not differ significantly between patients without versus those with CAS. By multivariate analysis, CAS was not independently predictive of late MACE rates (HR=0.85, [95%CI 0.50-1.78], p=0.85).

CONCLUSIONS

CAS was not associated with worse outcomes following TAVR. The relative prognostic significance of CAS in patients considered for either surgical or transcatheter valve replacement merits further research.

Prevalence and predictors of carotid artery stenosis in patients with severe aortic stenosis undergoing transcatheter aortic valve implantation

OBJECTIVES

Our aim was to analyze the prevalence and predictors of Carotid artery stenosis (CAS) in patients undergoing transcatheter aortic valve implantation (TAVI).

BACKGROUND

CAS is associated with the risk of periprocedural stroke in patients undergoing cardiac surgery. However, little is known about the prevalence of and clinical significance of CAS in the setting of TAVI.

METHODS

Consecutive patients undergoing a carotid Doppler study the day before TAVI were followed prospectively. CAS was defined in accordance with current practice guidelines. Logistic regression models were used to identify independent correlates of CAS.

RESULTS

The study included 171 patients (age 82 ± 6, male gender 47%). Carotid atherosclerosis (CA, defined as any carotid plaque) was present in 164 (96%) of patients, and CAS (peak systolic velocity [PSV] ≥ 125 cm/sec; ≥50% diameter stenosis) in 57 (33%) patients. Severe CAS (PSV ≥ 230 cm/sec; ≥70% stenosis, or near occlusion) was found in 15 (9%) patients. By multivariate analysis, smoking and a higher Euroscore independently predicted the presence of CAS. Patients in the present TAVI cohort had a significantly higher prevalence of both unilateral and bilateral CAS ≥ 50% than those in a previously reported cohort (n = 494 patients, age ≥ 70) undergoing clinically driven coronary angiography (33% vs. 20%, OR = 1.9, P = 0.001; and, 13% vs. 6%, OR = 2.3, P = 0.003, respectively). CAS was not independently associated with 30-day mortality or stroke rates.

CONCLUSIONS

The prevalence of CAS in patients undergoing TAVI is high, exceeding that observed in patients undergoing catheterization for coronary indications. The impact of CAS on clinical outcomes following TAVI merits further research.

Toll-like receptors and ischemic brain injury

Toll-like receptors (TLRs) are master regulators of innate immunity and play an integral role in the activation of inflammatory response during infections. In addition, TLRs influence the body's response to numerous forms of injury. Recent data have shown that TLRs play a modulating role in ischemic brain damage after stroke. Interestingly, their stimulation before ischemia induces a tolerant state that is neuroprotective. This phenomenon, referred to as TLR preconditioning, is the result of the reprogramming of TLR response to ischemic injury. This review addresses the role of TLRs in brain ischemia and the activation of endogenous neuroprotective pathways in the setting of preconditioning. We highlight the protective role of interferon-related response and the potential site of action for TLR preconditioning involving the blood-brain barrier. Pharmacologic modulation of TLR activation to promote protection against stroke is a promising approach for the development of prophylactic and immediate therapies targeting ischemic brain injury.

Neurologic complications of catheter ablation/defibrillators/pacemakers

Approaches to the management of patients with cardiac arrhythmias have significantly evolved over the last decade, with advancement in catheter ablation and device implantation techniques. As the techniques and tools evolve, so does our understanding of the possible complications from these procedures. The focus of this chapter is discussion of the neurologic complications involved with catheter ablation, pacemaker and defibrillation implantation, with the focus on timely diagnosis, and management strategies.

Incidence, predictors, origin and prevention of early and late neurological events after transcatheter aortic valve implantation (TAVI): a comprehensive review of current data

Transcatheter aortic valve implantation (TAVI) is a novel treatment option for patients with severe, symptomatic aortic valve stenosis considered inoperable or at high risk for surgical aortic valve replacement. Despite rapid adoption of this technology into clinical application, however, recent randomized controlled clinical trials have raised safety concerns regarding an increased risk of neurological events with TAVI compared to both medical treatment and conventional, surgical aortic valve replacement. Moreover, neuro-imaging studies have revealed an even higher incidence of new, albeit clinically silent cerebral lesions as a surrogate for procedural embolization. In this article, we review currently available data on the incidence, timing, predictors, prognostic implications and potential mechanisms of neurological events after TAVI.

Cerebral embolization during transcatheter aortic valve implantation: a transcranial Doppler study

BACKGROUND

Transcatheter aortic valve implantation (TAVI) is associated with a higher risk of neurological events for both the transfemoral and transapical approach than surgical valve replacement. Cerebral magnetic resonance imaging has revealed more new, albeit clinically silent lesions from procedural embolization, yet the main source and predominant procedural step of emboli remain unclear.

METHODS AND RESULTS

Eighty-three patients underwent transfemoral (Medtronic CoreValve [MCV(TF)], n=32; Edwards Sapien [ES(TF)], n=26) and transapical (ES(TA): n=25) TAVI. Serial transcranial Doppler examinations before, during, and 3 months after TAVI were used to identify high-intensity transient signals (HITS) as a surrogate for microembolization. Procedural HITS were detected in all patients, predominantly during manipulation of the calcified aortic valve while stent valves were being positioned and implanted. The balloon-expandable ES prosthesis caused significantly more HITS (mean [95% CI]) during positioning (ES(TF), 259.9 [184.8-334.9]; ES(TA), 206.1[162.5-249.7]; MCV(TF), 78.5 [25.3-131.6]; P<0.001) and the self-expandable MCV prosthesis during implantation (MCV(TF), 397.1 [302.1-492.2]; ES(TF), 88.2 [70.2-106.3]; ES(TA), 110.7 [82.0-139.3]; P<0.001). Overall, there were no significant differences between transfemoral and transapical TAVI or between the MCV and ES prostheses. No HITS were detected at baseline or 3-month follow-up. There was 1 major procedural stroke that resulted in death and 1 minor procedural stroke with full recovery at 3-month follow-up in the MCV group.

CONCLUSIONS

Procedural HITS were detected by transcranial Doppler in all patients. Although no difference was observed between the transfemoral and the transapical approach with the balloon-expandable ES stent valve, transfemoral TAVI with the self-expandable MCV prosthesis resulted in the greatest number of HITS, predominantly during implantation.