Fingolimod initiation in multiple sclerosis patients is associated with potential beneficial cardiovascular autonomic effects

Stroke risk in multiple sclerosis: a critical appraisal of the literature

Observational studies suggest that the occurrence of stroke on multiple sclerosis (MS) patients is higher compared to the general population. MS is a heterogeneous disease that involves an interplay of genetic, environmental and immune factors. The occurrence of stroke is subject to a wide range of both modifiable and non-modifiable, short- and long-term risk factors. Both MS and stroke share common risk factors. The immune mechanisms that underlie stroke are similar to neurodegenerative diseases and are attributed to neuroinflammation. The inflammation in autoimmune diseases may, therefore, predispose to an increased risk for stroke or potentiate the effect of conventional stroke risk factors. There are, however, additional determinants that contribute to a higher risk and incidence of stroke in MS. Due to the challenges that are associated with their differential diagnosis, the objective is to present an overview of the factors that may contribute to increased susceptibility or occurrence of stroke in MSpatients by performing a review of the available to date literature. As both MS and stroke can individually detrimentally affect the quality of life of afflicted patients, the identification of factors that contribute to an increased risk for stroke in MS is crucial for the prompt implementation of preventative therapeutic measures to limit the additive burden that stroke imposes.

S1P receptor modulators and the cardiovascular autonomic nervous system in multiple sclerosis: a narrative review

Sphingosine 1-phosphate (S1P) receptor (S1PR) modulators have a complex mechanism of action, which are among the most efficient therapeutic options in multiple sclerosis (MS) and represent a promising approach for other immune-mediated diseases. The S1P signaling pathway involves the activation of five extracellular S1PR subtypes (S1PR1-S1PR5) that are ubiquitous and have a wide range of effects. Besides the immunomodulatory beneficial outcome in MS, S1P signaling regulates the cardiovascular function via S1PR1-S1PR3 subtypes, which reside on cardiac myocytes, endothelial, and vascular smooth muscle cells. In our review, we describe the mechanisms and clinical effects of S1PR modulators on the cardiovascular system. In the past, mostly short-term effects of S1PR modulators on the cardiovascular system have been studied, while data on long-term effects still need to be investigated. Immediate effects detected after treatment initiation are due to parasympathetic overactivation. In contrast, long-term effects may arise from a shift of the autonomic regulation toward sympathetic predominance along with S1PR1 downregulation. A mild increase in blood pressure has been reported in long-term studies, as well as decreased baroreflex sensitivity. In most studies, sustained hypertension was found to represent a significant adverse event related to treatment. The shift in the autonomic control and blood pressure values could not be just a consequence of disease progression but also related to S1PR modulation. Reduced cardiac autonomic activation and decreased heart rate variability during the long-term treatment with S1PR modulators may increase the risk for subsequent cardiac events. For second-generation S1PR modulators, this observation has to be confirmed in further studies with longer follow-ups. The periodic surveillance of cardiovascular function and detection of any cardiac autonomic dysfunction can help predict cardiac outcomes not only after the first dose but also throughout treatment.

PLAIN LANGUAGE SUMMARY

What is the cardiovascular effect of S1P receptor modulator therapy in multiple sclerosis? Sphingosine 1-phosphate (S1P) receptor (S1PR) modulators are among the most efficient therapies for multiple sclerosis. As small molecules, they are not only acting on the immune but on cardiovascular and nervous systems as well. Short-term effects of S1PR modulators on the cardiovascular system have already been extensively described, while long-term effects are less known. Our review describes the mechanisms of action and the short- and long-term effects of these therapeutic agents on the cardiovascular system in different clinical trials. We systematically reviewed the literature that had been published by January 2022. One hundred seven articles were initially identified by title and abstract using targeted keywords, and thirty-nine articles with relevance to cardiovascular effects of S1PR therapy in multiple sclerosis patients were thereafter considered, including their references for further accurate clarification. Studies on fingolimod, the first S1PR modulator approved for treating multiple sclerosis, primarily support the safety profile of this therapeutic class. The second-generation therapeutic agents along with a different treatment initiation approach helped mitigate several of the cardiovascular adverse effects that had previously been observed at the start of treatment. The heart rate may decrease when initiating S1PR modulators and, less commonly, the atrioventricular conduction may be prolonged, requiring cardiac monitoring for the first 6 h of medication. Continuous therapy with S1PR modulators can increase blood pressure values; therefore, the presence of arterial hypertension should be checked during long-term treatment. Periodic surveillance of the cardiovascular and autonomic functions can help predict cardiac outcomes and prevent possible adverse events in S1PR modulators treatment. Further studies with longer follow-ups are needed, especially for the second-generation of S1PR modulators, to confirm the safety profile of this therapeutic class.

Cardiovascular medication seems to promote recovery of autonomic dysfunction after stroke

Background

Stroke may compromise cardiovascular–autonomic modulation (CAM). The longitudinal post-stroke CAM alterations remain unclear as previous studies excluded patients with cardiovascular medication. This study evaluated whether CAM dysfunction improves after several months in patients under typical clinical conditions, i.e., without excluding patients with cardiovascular medication.

Methods

In 82 ischemic stroke patients [33 women, 64.9 ± 8.9 years, NIHSS-scores 2 (interquartile range 1–5)], we evaluated the applications of cardiovascular medication before stroke, during autonomic tests performed within 1 week, 3 and 6 months after stroke onset. We determined resting RR intervals (RRI), systolic, diastolic blood pressures (BPsys), respiration, parameters reflecting total CAM [RRI-standard deviation (RRI-SD), RRI-total powers], sympathetic [RRI-low-frequency powers (RRI-LF), BPsys-LF powers] and parasympathetic CAM [RMSSD, RRI-high-frequency powers (RRI-HF powers)], and baroreflex sensitivity. ANOVA or Friedman tests with post hoc analyses compared patient data with data of 30 healthy controls, significance was assumed for P < 0.05.

Results

More patients had antihypertensive medication after than before stroke. First-week CAM testing showed lower RRIs, RMSSD, RRI-SDs, RRI-total powers, RRI-HF powers, and baroreflex sensitivity, but higher BPsys-LF powers in patients than controls. After 3 and 6 months, patients had significantly higher RRIs, RRI-SDs, RRI-total powers, RMSSDs, RRI-HF powers, and baroreflex sensitivity, but lower BPsys-LF powers than in the 1st week; RMSSDs and RRI-HF powers no longer differed between patients and controls. However, 6-month values of RRIs, RRI-SDs, and baroreflex sensitivity were again lower in patients than controls.

Conclusions

Even mild strokes compromised cardiovagal modulation and baroreflex sensitivity. After 3 months, CAM had almost completely recovered. Recovery might be related to the mild stroke severity. Presumably, CAM recovery was also promoted by the increased application of cardiovascular medication. Yet, slight CAM dysfunction after 6 months suggests continuing autonomic vulnerability.

Supplementary Information

The online version contains supplementary material available at 10.1007/s00415-022-11204-w.

Posterior circulation ischemic stroke not involving the brainstem is associated with cardiovascular autonomic dysfunction

BACKGROUND AND PURPOSE

Ischemic stroke may induce cardiovascular autonomic dysfunction. Yet, most previous studies included patients with anterior circulation ischemic stroke or brainstem stroke. It remains unclear whether posterior circulation ischemic stroke (PCIS) without brainstem involvement also compromises cardiovascular autonomic modulation (CAM). Therefore, we aimed to assess CAM in PCIS patients with and without brainstem involvement.

METHODS

In four subgroups of 61 PCIS-patients (14 occipital lobe, 16 thalamic, 12 cerebellar, and 19 brainstem strokes) and 30 healthy controls, we recorded RR-intervals (RRI), systolic, diastolic blood pressures (BPsys, BPdia), and respiration at supine rest during the first week after stroke-onset. We calculated parameters reflecting total CAM [RRI-standard-deviation (RRI-SD), RRI-total-powers], predominantly sympathetic CAM [RRI-low-frequency-powers (RRI-LF-powers) and BPsys-LF-powers] and parasympathetic CAM [Root-Mean-Square-of-Successive-RRI-Differences (RMSSD), RRI-high-frequency-powers (RRI-HF-powers)], sympathetic-parasympathetic balance (RRI-LF/HF-ratios), and baroreflex-sensitivity (BRS). Values were compared between the four PCIS-groups and controls using one-way ANOVA Kruskal-Wallis-tests, with post-hoc analyses. Significance was assumed for P<0.05.

RESULTS

In each PCIS-subgroup, values of RRI, RRI-SD, RMSSD, RRI-HF-powers, and BRS were significantly lower, while BPsys-LF-powers were higher than in the controls. Only in patients with occipital lobe stroke, RRI-LF/HF-ratios were significantly higher than in controls. Otherwise, autonomic parameters did not differ between the four PCIS-subgroups.

CONCLUSIONS

During the first week after stroke-onset, our PCIS patients with occipital lobe, thalamic, cerebellar, or brainstem strokes all had reduced cardiovagal modulation, compromised baroreflex, and increased peripheral sympathetic modulation. The RRI-LF/HF-ratios suggest that sympathetic predominance is slightly more prominent after occipital lobe stroke. PCIS may trigger cardiovascular autonomic dysfunction even without brainstem involvement.

Cardiovascular fingolimod effects on rapid baroreceptor unloading are counterbalanced by baroreflex resetting

Background and purpose

Initial cardiovascular fingolimod effects might compromise baroreflex responses to rapid blood pressure (BP) changes during common Valsalva-like maneuvers. This study evaluated cardiovascular responses to Valsalva maneuver (VM)-induced baroreceptor unloading and loading upon fingolimod initiation.

Patients and methods

Twenty-one patients with relapsing-remitting multiple sclerosis performed VMs before and 0.5, 1, 2, 3, 4, 5, and 6 hours after fingolimod initiation. We recorded heart rate (HR) as RR intervals (RRI), systolic and diastolic BP (BPsys, BPdia) during VM phase 1, VM phase 2 early, VM phase 2 late, and VM phase 4. Using linear regression analysis between decreasing BPsys and RRI values during VM phase 2 early, we determined baroreflex gain (BRG) reflecting vagal withdrawal and sympathetic activation upon baroreceptor unloading. To assess cardiovagal activation upon baroreceptor loading, we calculated Valsalva ratios (VR) between maximal and minimal RRIs after strain release. Analysis of variance or Friedman tests with post hoc analysis compared corresponding parameters at the eight time points (significance: p < 0.05).

Results

RRIs at VM phase 1, VM phase 2 early, and VM phase 2 late were higher after than before fingolimod initiation, and maximal after 4 hours. Fingolimod did not affect the longest RRIs upon strain release, but after 3, 5, and 6 hours lowered the highest BPsys values during overshoot and all BPdia values, and thus reduced VRs. BRG was slightly higher after 3 and 5 hours, and significantly higher after 4 hours than before fingolimod initiation.

Conclusions

VR-decreases 3–6 hours after fingolimod initiation are physiologic results of fingolimod-associated attenuations of BP and HR increases at the end of strain and do not suggest impaired cardiovagal activation upon baroreceptor loading. Stable and at the time of HR nadir significantly increased BRGs indicate improved responses to baroreceptor unloading. Thus, cardiovascular fingolimod effects do not impair autonomic responses to sudden baroreceptor loading or unloading but seem to be mitigated by baroreflex resetting.

A Comprehensive Monitoring Study on Electrocardiographic Assessments and Cardiac Events After Fingolimod First Dose-Possible Predictors of Cardiac Outcomes

Background: First dose observation for cardiac effects is required for fingolimod. Previous results in patients with relapsing remitting multiple sclerosis (RRMS) suggest that transient bradycardia and conduction abnormalities during the observation phase are rare, benign and reversible. Prior analyses corroborate these findings. The present large scale dataset allows subgroup analyses for differences in the incidence of cardiac findings depending on patient characteristics.

Methods: START was an open-label, multi-center study that enrolled 6,998 RRMS patients. Primary endpoints were incidence of bradycardia (heart rate < 45 bpm) and second-/third-degree atrioventricular (AV) block during treatment initiation. Subgroup analyses were performed according to age, gender, body mass index (BMI), baseline expanded disability status scale (EDSS), and concomitant medication to determine the impact of these variables on cardiac outcomes parameters.

Results: 63 patients (0.9%) developed bradycardia (<45 bpm), 120 patients (1.7%) had a second-degree Mobitz I (Wenkebach) block and/or 2:1 AV block. One case of an asymptomatic third-degree AV block occurred. No Mobitz II AV block was observed. After 1 week, no second-/third-degree AV block was observed. The incidence of second- or third-degree AV blocks was significantly higher in older patients (≥50 years; p = 0.014 vs. patients 35–49 years). Second- or third-degree AV blocks were more frequent in females (87.5% of all patients with a second- or third-degree AV block; p < 0.001), while bradycardia occurred more often in males (58.7% of all bradycardia events; p < 0.001). Furthermore, patients with a BMI below 25 had a higher incidence of second- or third-degree AV block.

Conclusions: In summary, transient bradycardia and AV conduction abnormalities after the first dose of fingolimod were rare and asymptomatic. When compared to females, male patients might have a higher risk for bradycardia during treatment initiation, presumably due to a lower resting heart rate. Furthermore, a low heart rate before treatment initiation, low body weight, or low BMI possibly increases the risk for bradycardia. Second- or third-degree AV blocks were more frequent in females, older patients and patients with a low BMI. Nevertheless, these cardiac events remained rare and benign, confirming the favorable cardiac safety profile of fingolimod upon treatment initiation in MS patients without cardiovascular comorbidities.

Cardiac Autonomic Dysfunction in Multiple Sclerosis: A Systematic Review of Current Knowledge and Impact of Immunotherapies

Cardiac autonomic dysfunction (CAD) has been reported in patients with multiple sclerosis (MS). This systematic review summarizes the evidence for the types and prevalence of CAD in MS patients, as well as its association with MS type, disease characteristics, fatigue and immunotherapies used to treat MS. The analysis revealed that CAD is correlated with pathophysiological processes of MS, can trigger serious cardiovascular complications that may reduce life expectancy, and may have implications for treatment with immunotherapies, especially fingolimod. Numerous mainly small case-control or cohort studies have reported various measures of CAD (particularly heart rate variation) in MS patients, showing higher rates of abnormality versus controls. A smaller number of studies have reported on cardiac autonomic symptoms in MS, including orthostatic intolerance/dizziness in around 50% of patients. CAD also appears to be associated with disease duration and to be more common in progressive than relapsing-remitting MS. However, although a substantial evidence base suggests that assessing CAD in people with MS may be important, standardised methods to evaluate CAD in these patients have not yet been established. In addition, no studies have yet looked at whether treating CAD can reduce the burden of MS symptoms, disease activity or the rate of progression.

Cardiovascular autonomic individual profile of relapsing-remitting multiple sclerosis patients and risk of extending cardiac monitoring after first dose fingolimod

Fingolimod exerts its therapeutic effect in multiple sclerosis by modulating sphingosine-1P receptors which are expressed in the heart mediating fingolimod first dose effects. Understanding potential interactions of baseline characteristics and autonomic profile with fingolimod first dose effects may add novel safety information and help explain cases requiring extension of the 6-hour ECG monitoring period. We aimed at characterizing the patient population treated with the first dose of fingolimod in clinical practice in an observational, multicenter, prospective 6-hours (up to 24) study. ECG was recorded for 15 min before first fingolimod administration and for 6 h after. Heart rate (HR) and HR variability in the frequency domain were derived from ECG traces. Out of the 625 enrolled patients, 580 (92.8%) were discharged at the sixth hour after fingolimod first dose; 45 (7.2%) required monitoring extension. Data confirm the well characterized cardiovascular fingolimod profile upon treatment initiation. Ten (1.6%) patients showed an atrioventricular block, all asymptomatic and self-resolving. Normalized spectral power in the High Frequency band (marking vagal modulation) and previous annualized relapse rate were independently correlated with the probability of undergoing extended monitoring. Our results could provide useful information for the stratification and individualized monitoring of MS patients prescribed with fingolimod.

Cerebral lesion correlates of sympathetic cardiovascular activation in multiple sclerosis

Cardiovascular autonomic dysfunction is common in multiple sclerosis (MS) and contributes significantly to disability. We hypothesized that cerebral MS‐lesions in specific areas of the central autonomic network might account for imbalance of the sympathetic and parasympathetic cardiovascular modulation. Therefore, we used voxel‐based lesion symptom mapping (VLSM) to determine associations between cardiovascular autonomic dysfunction and cerebral MS‐related lesion sites. In 74 MS‐patients (mean age 37.0 ± 10.5 years), we recorded electrocardiographic RR‐intervals and systolic and diastolic blood pressure. Using trigonometric regressive spectral analysis, we assessed low (0.04–0.15 Hz) and high (0.15–0.5 Hz) frequency RR‐interval‐and blood pressure‐oscillations and determined parasympathetically mediated RR‐interval–high‐frequency modulation, mainly sympathetically mediated RR‐interval–low‐frequency modulation, sympathetically mediated blood pressure‐low‐frequency modulation, and the ratios of sympathetic and parasympathetic RR‐interval‐modulation as an index of sympathetic‐parasympathetic balance. Cerebral MS‐lesions were analyzed on imaging scans. We performed a VLSM‐analysis correlating parameters of autonomic dysfunction with cerebral MS‐lesion sites. The VLSM‐analysis showed associations between increased RR‐interval low‐frequency/high‐frequency ratios and lesions most prominently in the left insular, hippocampal, and right frontal inferior opercular region, and a smaller lesion cluster in the right middle cerebellar peduncle. Increased blood pressure‐low‐frequency powers were associated with lesions primarily in the right posterior parietal white matter and again left insular region. Our data indicate associations between a shift of cardiovascular sympathetic‐parasympathetic balance toward increased sympathetic modulation and left insular and hippocampal lesions, areas of the central autonomic network. The VLSM‐analysis further distinguished between right inferior fronto‐opercular lesions disinhibiting cardiac sympathetic activation and right posterior parietal lesions increasing sympathetic blood pressure modulation.

Acute Fingolimod Effects on Baroreflex and Cardiovascular Autonomic Control in Multiple Sclerosis

Background:

Fingolimod, an oral drug used in multiple sclerosis (MS) treatment, exerts its action through S1P-receptor engagement. These receptors are also expressed in heart and endothelial cells. The engagement of receptors on the atrial heart myocytes may cause a slowing effect on heart rate (HR). We aimed to explore the acute effect of fingolimod on the cardiac autonomic control, a side-effect of the drug that still needs to be clarified.

Methods:

In 10 MS patients, we investigated the influence of the first administration of fingolimod (0.5 mg) on sympathetic and parasympathetic indexes via the analysis of the HR variability, and on the baroreflex sensitivity via sequence and alpha coefficient techniques.

Results:

Fingolimod produced an average HR maximal drop of 12.7 (7.8) beats/min and the minimal HR occurred after 2.73 (0.38) hours from the dose administration. The pulse interval (PI) mean value and the pNN50 and RMSSD indexes of parasympathetic drive to the heart significantly increased. Interestingly, in 6 out of 10 patients also the power in the low-frequency band (LF) increased. The baroreflex sensitivity was not modified by the first dose of the drug.

Conclusions:

Our findings indicate that although the first dose of fingolimod invariably activates the parasympathetic system, in several subjects, it may induce also a surge in the sympathetic cardiac drive. This suggests that not only the vagal, as usually assumed, but also the sympathetic autonomic branch should be considered in the risk profile assessment of MS patients starting treatment with fingolimod.

Spectral Analysis of Heart Rate Variability: Time Window Matters

Spectral analysis of heart rate variability (HRV) is a valuable tool for the assessment of cardiovascular autonomic function. Fast Fourier transform and autoregressive based spectral analysis are two most commonly used approaches for HRV analysis, while new techniques such as trigonometric regressive spectral (TRS) and wavelet transform have been developed. Short-term (on ECG of several minutes) and long-term (typically on ECG of 1–24 h) HRV analyses have different advantages and disadvantages. This article reviews the characteristics of spectral HRV studies using different lengths of time windows. Short-term HRV analysis is a convenient method for the estimation of autonomic status, and can track dynamic changes of cardiac autonomic function within minutes. Long-term HRV analysis is a stable tool for assessing autonomic function, describe the autonomic function change over hours or even longer time spans, and can reliably predict prognosis. The choice of appropriate time window is essential for research of autonomic function using spectral HRV analysis.

Modulation of Cardiac Autonomic Function by Fingolimod Initiation and Predictors for Fingolimod Induced Bradycardia in Patients with Multiple Sclerosis

Objective: It is well-known that initiation of fingolimod induces a transient decrease of heart rate. However, the underlying cardiac autonomic regulation is poorly understood. We aimed to investigate the changes of autonomic activity caused by the first dose of fingolimod using a long-term multiple trigonometric spectral analysis for the first time. In addition, we sought to use the continuous Holter ECG recording to find predictors for fingolimod induced bradycardia.

Methods: Seventy-eight patients with relapsing-remitting multiple sclerosis (RRMS) were included. As a part of the START study (NCT01585298), continuous electrocardiogram was recorded before fingolimod initiation, and until no <6 h post medication. Time domain and frequency domain heart rate variability (HRV) parameters were computed hourly to assess cardiac autonomic regulation. A long-term multiple trigonometric regressive spectral (MTRS) analysis was applied on successive 1-h-length electrocardiogram recordings. Decision tree analysis was used to find predictors for bradycardia following fingolimod initiation.

Results: Most of the HRV parameters representing parasympathetic activities began to increase since the second hour after fingolimod administration. These changes of autonomic regulations were in accordance with the decline of heart rate. Baseline heart rate was highly correlated with nadir heart rate, and was the only significant predicting factor for fingolimod induced bradycardia among various demographic, clinical and cardiovascular variables in the decision tree analysis.

Conclusions: The first dose application of fingolimod enhances the cardiac parasympathetic activity during the first 6 h post medication, which might be the underlying autonomic mechanism of reduced heart rate. Baseline heart rate is a powerful predictor for bradycardia caused by fingolimod.