Our data show that there has been little systematic assessment of dizziness types among patients with primary cardiovascular disorders, and among those who do experience dizziness, vertigo appears to be frequent, rather than rare (~63%, including ~37% where vertigo was the only dizziness type reported). These findings question current clinical practice in the assessment of patients with dizziness. Specifically, using the presence of vertigo to exclude cardiovascular disorders from differential diagnostic consideration is not an evidence-based practice.
Among over 1,500 studies captured by our search, we found only 5 with data on the frequency of vertigo in cardiovascular disease. Contrary to conventional wisdom, none supported the contention that vertigo was rare among patients with dizziness of cardiovascular cause. From the most rigorously designed of these studies, we estimated that 10% of patients with primary cardiovascular disease may experience dizziness as a dominant or presenting symptom16. This estimate, based on patients with acute myocardial infarction, is probably a lower bound for the prevalence of symptomatic dizziness in cardiovascular diseases causing hypotension, given that 55-71% of syncope patients describe some form of dizziness just prior to their faint21,22.
It is perhaps surprising that there are so few studies on this subject, when dizziness is the third most common major medical complaint seen in primary care1 and affects more than 20% of the general population3. In part, the absence of data reflects the general dearth of symptom-oriented research studies23. However, with dizziness, the entrenched quality-of-symptoms diagnostic approach (“vertigo is vestibular” and “presyncope is cardiovascular”) may have contributed to the lack of scientific inquiry5. There has been an artificial segregation of dizziness from syncope research3 with neuro-otology research (focused on vertigo and vestibular causes) and cardiology research (focused on syncope and primary cardiovascular disease) each conducted largely in isolation5. Major syncope studies have expressly excluded patients with dizziness or vertigo24-26. As a result, there have been no comprehensive clinical or epidemiologic studies of dizziness in unselected patients3,27.
Given the empiric association between cardiovascular disease and vertigo shown here, it is reasonable to question whether there is a biologically plausible pathomechanism. It is known that vertigo often results from physiologic imbalance (usually right versus left) in the vestibular system28. It is conceivable that vertigo might also be a symptom of disturbed spatial perception5, even in the absence of frank right-left vestibular asymmetry; hence, global cerebral hypoperfusion (in association with systemic hypotension) might be sufficient explanation. Alternatively, we might postulate that global reductions in blood pressure lead to local asymmetries in blood flow to the vestibular system (because of congenital or acquired left-right asymmetries in vascular caliber), thereby causing vertigo via a transient-ischemic-attack-type mechanism, as has been suggested previously11. Finally, we might theorize that parts of the vestibular system are differentially susceptible to global drops in pressure29—either as a result of normal differences in collateral vascular supply to different parts of the vestibular end organ30 or differential neuronal susceptibility to ischemia, as has been shown for subpopulations of cochlear hair cells31. Thus, there is no cause to dismiss the empiric findings of our review on theoretical grounds of biologic implausibility.
From a clinical standpoint, our findings indicate that the presence of vertigo should not obviate the need to search for a cardiovascular cause. However, we do not suggest that every vertiginous patient should undergo a complete workup for all possible cardiac disorders. For instance, it is hard to imagine that patients with acute vestibular syndrome (continuous vertigo, nausea, vomiting, nystagmus, gait unsteadiness, and head motion intolerance, lasting days to weeks), as seen with vestibular neuritis or labyrinthitis, could have an underlying cardiac etiology. Here, the combination of symptom timing (continuous, lasting days or longer), triggers (exacerbation by head motion), and associated symptoms and signs (nystagmus, gait unsteadiness) presumably obviate the need to search for cardiac pathology. However, in patients with brief or intermittent dizziness that is either untriggered or brought on by exertion, caution should be exercised before dismissing a dangerous cardiac cause, even in the absence of chest pain, dyspnea, or other frankly cardiac symptoms11.
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