A population-based study of stroke in the setting of mitral valve prolapse: risk factors and infarct subtype classification

Stroke in mitral valve prolapse: risk factors and left atrial function in cryptogenic versus non-cryptogenic ischemic subtypes

Background and purpose

Mitral valve prolapse (MVP) has been associated with an increased risk of ischemic stroke. Older age, thicker mitral leaflets, and significant mitral regurgitation (MR) leading to atrial fibrillation have been traditionally considered risk factors for ischemic stroke in MVP. However, specific risk factors for MVP-stroke subtypes are not well defined. The aim of this study is to evaluate clinical and echocardiographic parameters, including left atrial (LA) function, in MVP with cryptogenic (C) vs. non-cryptogenic (NC) stroke.

Methods

In this case-control matched study, MVPs were identified in consecutive echocardiograms obtained after a stroke from January 2013 to December2016 at the University of California, San Francisco. MVP was defined as leaflet displacement ≥2 mm in the parasternal long-axis view at end-systole. Age/gender matched MVPs without stroke and healthy controls without MVP were also identified. We analyzed LA end-systolic/diastolic volume index, emptying fraction (LAEF), function index (LAFI), and global longitudinal strain in all MVPs and controls. We also measured left ventricular (LV) volume indexes, mass index, ejection fraction (EF), degree of MR and leaflet thickness.

Results

We identified a total of 30 MVPs (age 70 ± 12, 50% females) with stroke (11 with C- and 19 with NC-stroke), 20 age/gender matched MVPs without a stroke and 16 controls. MVPs without stroke had lower BMI, less hypertension but more MR (≥moderate in 45% vs. 17%), more abnormal LA function (lower LAEF, LAFI) and larger LV volumes/mass (all p < 0.05) when compared to MVPs with stroke. Leaflet thickness was overall mild (<3 mm) and similar in the 2 groups. Within the MVP stroke group, NC-stroke had higher BMI, more hypertension and more atrial fibrillation compared to C-stroke. In the variables tested, patients with C-stroke did not differ from controls.

Conclusions

MVP-related MR may be protective against stroke despite abnormal LA function. Risk of NC-stroke in MVP is related to common stroke risk factors rather than mitral valve leaflet thickness. The etiology of C-stroke in MVP warrants further studies.

Prevention of cardioembolic stroke

Cardiac causes of ischemic stroke lead to severe neurological deficits from large intracranial artery occlusion compared to small vessel ischemic stroke. The most common cause of cardioembolic stroke is atrial fibrillation (AF), which has an increasing incidence with age. AF stroke trials demonstrate that anti-coagulation is superior to anti-platelet therapy in terms of ischemic stroke prevention. Recently, warfarin was compared with dabigatran, an oral, direct thrombin inhibitor, and was found to be at least equally effective in reducing ischemic stroke with less intracranial bleeding risk. Future research is investigating other direct thrombin inhibitors as potential alternatives to warfarin, which has a narrow therapeutic index, requires frequent blood monitoring, has multiple drug interactions, and a higher rate of intracranial bleeding. Other causes of cardioembolic stroke include myocardial infarction, left ventricular thrombus, reduced ejection fraction, valvular abnormalities, and endocarditis. Patent foramen ovale is a common finding on echocardiograms in patients with and without stroke (up to 20% of the population), and it is a controversial source of cryptogenic stroke. The best way to prevent cardioembolic stroke remains early detection and treatment of AF, and treating the underlying stroke mechanism. Cardiac magnetic resonance imaging is an emerging technology and reveals some sources of cardiac embolism missed by echocardiography, and might provide an additional diagnostic tool in investigating cardioembolic stroke.

Stroke prevention in atrial fibrillation and other major cardiac sources of embolism

The frequency of cardioembolic stroke is expected to rise as the general population ages. Much of the increase may be attributed to atrial fibrillation, the most common cause of cardioembolic stroke and one that plays a substantial role in aging adults. Other sources of cardioembolic stroke may include ventricular thrombus from myocardial infarction, heart failure, structural heart defects such as patent foramen ovale (PFO), atrial septal aneurysm, proximal aortic atheroma, valvular heart disease, and endocarditis. Diagnostic studies, such as neuroimaging, ECG, and echocardiography, are helpful in uncovering cardioembolic sources of stroke. Medical therapy is predicated on the underlying mechanism. For example, warfarin may be indicated in certain patients who have atrial fibrillation, atrial, or ventricular thrombi, and PFO with atrial septal aneurysm and cryptogenic stroke in select young patients to prevent stroke. Newer diagnostic technologies, including multidetector CT and cardiac MRI, may be useful to diagnose cardiac causes of stroke when transesophageal echocardiography is indeterminate or cryptogenic stroke is present.

National Stroke Association guidelines for the management of transient ischemic attacks

OBJECTIVE

Transient ischemic attacks are common and important harbingers of subsequent stroke. Management varies widely, and most published guidelines have not been updated in several years. We sought to create comprehensive, unbiased, evidence-based guidelines for the management of patients with transient ischemic attacks.

METHODS

Fifteen expert panelists were selected based on objective criteria, using publication metrics that predicted nomination by practitioners in the field. Prior published guidelines were identified through systematic review, and recommendations derived from them were rated independently for quality by the experts. Highest quality recommendations were selected and subsequently edited by the panelists using a modified Delphi approach with multiple iterations of questionnaires to reach consensus on new changes. Experts were provided systematic reviews of recent clinical studies and were asked to justify wording changes based on new evidence and to rate the final recommendations based on level of evidence and quality. No expert was allowed to contribute to recommendations on a topic for which there could be any perception of a conflict of interest.

RESULTS

Of 257 guidelines documents identified by systematic review, 13 documents containing 137 recommendations met all entry criteria. Six iterations of questionnaires were required to reach consensus on wording of 53 final recommendations. Final recommendations covered initial management, evaluation, medical treatment, surgical treatment, and risk factor management.

INTERPRETATION

The final recommendations on the care of patients with transient ischemic attacks emphasize the importance of urgent evaluation and treatment. The novel approach used to develop these guidelines is feasible, allows for rapid updating, and may reduce bias.

Mitral valve prolapse

Mitral valve prolapse is a common valvular abnormality that is the most common cause of severe non-ischaemic mitral regurgitation in the USA. The overall prognosis of patients with mitral valve prolapse is excellent, but a small subset will develop serious complications, including infective endocarditis, sudden cardiac death, and severe mitral regurgitation. We present a comprehensive review of mitral valve prolapse, examining normal mitral anatomy, the clinical and echocardiographic features of mitral valve prolapse, and the pathophysiology and genetics of the disorder. We discuss the contemporary management of both asymptomatic and symptomatic prolapse, with particular attention to the timing and technique of surgical repair. We conclude that echocardiography is the method of choice for diagnosing mitral valve prolapse, that clinical and echocardiographic features can predict which patients with prolapse are at highest risk for complications, and that mitral valve repair is the treatment of choice for symptomatic prolapse.

Risk of ischaemic stroke in people with migraine: systematic review and meta-analysis of observational studies

OBJECTIVE

To explore the association between migraine and risk of ischaemic stroke.

DESIGN

Systematic review and meta-analysis.

DATA SOURCES

Observational studies published between 1966 and June 2004 (identified through Medline and Embase) that examined the association between migraine and risk of ischaemic stroke.

RESULTS

14 studies (11 case-control studies and 3 cohort studies) were identified. These studies suggest that the risk of stroke is increased in people with migraine (relative risk 2.16, 95% confidence interval 1.89 to 2.48). This increase in risk was consistent in people who had migraine with aura (relative risk 2.27, 1.61 to 3.19) and migraine without aura (relative risk 1.83, 1.06 to 3.15), as well as in those taking oral contraceptives (relative risk 8.72, 5.05 to 15.05).

CONCLUSIONS

Data from observational studies suggest that migraine may be a risk factor in developing stroke. More studies are needed to explore the mechanism of this potential association. In addition, the risk of migraine among users of oral contraceptives must be further investigated.

Basilar and Middle Cerebral Artery Reactivity in Patients With Migraine

BACKGROUND

Migraine has been reported as a possible risk factor for ischemic stroke. The mechanisms underlying this association are unknown.

OBJECTIVES

To evaluate cerebrovascular reactivity to hypercapnia in the anterior and posterior circulation of patients with migraine, as reduced cerebrovascular reactivity is associated with a predisposition to stroke in various clinical conditions.

METHODS

Using transcranial Doppler ultrasonography, changes in flow velocity during apnea were measured in both middle cerebral arteries and in the basilar artery of 15 control subjects and 30 patients with migraine (15 with aura and 15 without aura) during an attack-free period. Cerebrovascular reactivity was evaluated using the breath-holding index, which is calculated by dividing the percent increase in mean flow velocity recorded during a breath-holding episode by its duration (in seconds) after a normal inspiration.

RESULTS

Vascular reactivity in the middle cerebral arteries was similar in patients and controls and significantly lower in the basilar artery of patients with migraine with aura compared with the other 2 groups (P <.0001).

CONCLUSIONS

These findings show that in patients with migraine with aura, there is an impairment in the adaptive cerebral hemodynamic mechanisms in the posterior circulation. This fact could have pathogenetic implications since the association between migraine and stroke frequently regards patients with migraine with aura, and cerebral infarcts occur more commonly in the vertebrobasilar district.

Cerebral ischemic events after diagnosis of mitral valve prolapse: a community-based study of incidence and predictive factors

BACKGROUND AND PURPOSE

Association of mitral valve prolapse (MVP) with ischemic neurological events (INEs) is uncertain.

METHODS

In the community of Olmsted County (Minn), we identified all MVP diagnosed (1989 to 1998) in patients in sinus rhythm with no prior history of INE. We measured INE rates and compared them with expected rates in our community to define the excess risk of INE.

RESULTS

Among 777 eligible subjects (age, 49+/-20 years; 66% female; follow-up, 5.5+/-3.0 years), 30 patients had at least 1 INE during follow-up (at 10 years, 7+/-1%). Compared with expected INEs in the same community, subjects with MVP showed excess risk of lifetime INE (relative risk [RR], 2.2; 95% CI, 1.5 to 3.2; P<0.001) and during follow-up under purely medical management (RR, 1.8; 95% CI, 1.1 to 2.8; P=0.009). Independent determinants of INE were older age (RR, 1.08 per year; 95% CI, 1.04 to 1.11; P<0.001), mitral thickening (RR, 3.2; 95% CI, 1.4 to 7.4; P=0.008), atrial fibrillation (AFib) during follow-up (RR, 4.3; 95% CI, 1.9 to 10.0; P<0.001), and need for cardiac surgery (RR, 2.5; 95% CI, 1.1 to 5.8; P=0.03). INE 10-year rates were low in patients <50 years of age (0.4+/-0.4%, P=0.60 versus expected) but were excessive in patients >50 years of age (16+/-3%, P<0.001 versus expected) or with thickened leaflets (7+/-2%, P<0.001 versus expected). Predictors of follow-up AFib were age, mitral regurgitation, and left atrium diameter (all P<0.01).

CONCLUSIONS

In the community, subjects with MVP display a lifetime excess rate of INE compared with expected. Clinical (older age) and echocardiographic (leaflets thickening) characteristics define patients with MVP at high risk for INE, and subsequent AFib or need for cardiac surgery, both related to the degree of mitral regurgitation, increase the risk of INE.

Lack of evidence of an association between mitral-valve prolapse and stroke in young patients

BACKGROUND

Previous studies have reported a high prevalence of mitral-valve prolapse among patients with embolic stroke (28 to 40 percent), especially among young patients (those < or =45 years old); this finding has practical implications for prophylaxis. However, diagnostic criteria for prolapse have changed and are now based on three-dimensional analysis of the shape of the valve; use of the current criteria reduces markedly the frequency of such a diagnosis and increases its specificity. Previously described complications must therefore be reconsidered.

METHODS

In a case-control study, we reviewed data on 213 consecutive patients 45 years old or younger with documented ischemic stroke or transient ischemic attack between 1985 and 1995; they underwent complete neurologic and echocardiographic evaluations. The prevalence of prolapse in these patients was compared with that in 263 control subjects without known heart disease, who were referred to our institution for assessment of ventricular function before receiving chemotherapy.

RESULTS

Mitral-valve prolapse was present in 4 of the 213 young patients with stroke (1.9 percent), as compared with 7 of the 263 controls (2.7 percent); prolapse was present in 2 of 71 patients (2.8 percent) with otherwise unexplained stroke. The crude odds ratio for mitral-valve prolapse among the patients who had strokes, as compared with those who did not have strokes, was 0.70 (95 percent confidence interval, 0.15 to 2.80; P=0.80); after adjustment for age and sex, the odds ratio was 0.59 (95 percent confidence interval, 0.12 to 2.50; P=0.62).

CONCLUSIONS

Mitral-valve prolapse is considerably less common than previously reported among young patients with stroke or transient ischemic attack, including unexplained stroke, and no more common than among controls. Using more specific and currently accepted echocardiographic criteria, therefore, we could not demonstrate an association between the presence of mitral-valve prolapse and acute ischemic neurologic events in young people.

Role of routine transthoracic echocardiography in evaluation and management of stroke

OBJECTIVE

To determine the value of routine transthoracic echocardiography in patients with cerebral ischemia without known cardiac disease.

DESIGN

The literature from 1990 to 1995 was searched and relevant bibliographies from these papers reviewed. Articles reporting the prevalence and/or risk of stroke for myxoma, vegetation, mitral stenosis, left atrial thrombus, left ventricular thrombus or cardiomyopathy, patent foramen ovale, and atrial septal aneurysm were used. Prevalences and recurrent stroke risk were examined for adult patients less than and greater than 45 years.

RESULTS

Both the prevalence of transthoracic echocardiographic findings and recurrent risk of stroke differ by age. The finding of a patent foramen ovale can be expected in nearly half of younger patients with stroke, whilst transthoracic echo can be expected to yield no relevant lesion in three quarters of patients > 45 years. Warfarin anticoagulation appears beneficial in patients with mitral stenosis, left atrial thrombus, left ventricular thrombus, and left ventricular dysfunction, but is of unproven benefit for patent foramen ovale, atrial septal aneurysm, or in the absence of a risk-associated abnormality.

CONCLUSION

For most transthoracic echo findings in stroke, optimal management strategies have not been well defined. Future research is needed to evaluate the appropriate therapeutic approaches.