Despite technological progress, about 1 in 3 ischemic strokes remains cryptogenic. More than 30% of these patients will have a recurrent stroke in the next 5 years. Several studies in the last few years have brought into focus atrial fibrillation (AF) as the underlying etiology in a sizeable proportion of these patients, especially those above 60 years. The longer we look for atrial fibrillation, the more likely we are to find it. In the recently published CRYSTAL – AF trial, 12.4% patients had atrial fibrillation detected when monitored for 1 year. This is especially important, as the therapeutic implications are major.
Clinical, electrocardiographic and echocardiographic markers of atrial fibrillation may be especially important to assess in cryptogenic stroke patients, as they may point out which patients are more likely to have occult atrial fibrillation, and thus may need to be monitored longer. Left ventricular diastolic dysfunction (LVDD) is thought to be a marker of paroxysmal non-valvular AF.
In the current study, Seo et al. compared the prevalence of left ventricular diastolic dysfunction (LVDD) in cryptogenic stroke (CS) v/s stroke with AF and stroke without AF (lacunar strokes, and strokes with >50% referable large artery stenosis). Also, they compared the proportion of severe LVDD between CS patients with cardioembolism (CE)-mimic DWI pattern and non CE-mimic DWI pattern, with the aim to delineate if LVDD can be used as a marker to predict occult AF in CS patients with CE-mimic pattern on MRI. The study cohort consists of 1901 patients with acute stroke enrolled into a prospective registry at the Soonchunhyang University Hospital in Seoul, Korea between January 2004 to March 2013, with a mean age of 58 years. After excluding patients with missing workup, and patients with known sources for cardioembolism which may affect LVDD such as mechanical valve, mitral stenosis, atrial myxoma etc, 55 CS patients, 310 strokes with AF and 969 strokes without AF were included in analysis. LVDD was ascertained by 2 cardiologists and assigned grades I-III based on accepted parameters. When dichotomized at grade III, severe LVDD was much more prevalent in CS than stroke without AF, and almost comparable to stroke with AF. Moreover, among the CS patients, the presence of LVDD was much higher in CE-mimic patients than non-mimics. On the contrary, although left atrial enlargement (LAE) was predominantly detected in stroke with AF, its frequency was not different between CS and stroke without AF. In a multivariable model, LVDD was associated with stroke with AF, despite controlling for hypertension, LAE and PFO.
These findings are significant, as they validate LVDD being a marker for AF in a stroke population, despite controlling for hypertension. The fact that most of our current AF detection techniques including ambulatory cardiac telemetry or implantable devices are contingent on timing, more permanent markers are needed that precede or predict AF to save time and money. Also, in this study, LVDD proved to be a good, if not a more sensitive marker than LAE for AF. The higher prevalence of LVDD in CS with CE-mimic lesion distribution suggests that these patients likely have underlying AF as a cause for the CS. However, being a retrospective single center study, the findings cannot be generalizable to our stroke patients. Also, there may be an inherent selection bias because a significant proportion of patients, who did not have a full workup were excluded. Despite these limitations, it makes a strong argument for patients that suffer CS with CE mimic lesion patterns and have LVDD to undergo longer cardiac monitoring, as their risk of having AF is very high. In our aging population, where the prevalence of AF is predicted to double by 2050 to 5.5 million, tools to increase pre-test probability of detecting AF will help us tailor stroke care to individual stroke patients, while saving resources by avoiding unnecessary testing on others.