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Syncope in Structural Heart Disease
Study Questions:
What are the causes of recurrent syncope and clinical outcomes in patients with structural heart disease (SHD) and negative electrophysiologic study (EPS)?
Methods:
This was a prospective study of patients with syncope, SHD, and a negative EPS. All patients underwent head up tilt test (HUTT) and many also had an implantable loop recorder (ILR) inserted.
Results:
A total of 41 SHD patients (coronary artery disease, 27 [66%]; dilated cardiomyopathy, 14 [34.15%]) with mean ejection fraction 42 ± 4.8 (30-49%) were included. HUTT was positive in 25 (61%) (Group A) and negative in 16 (39%) (Group B). An ILR was implanted in 21/25 Group A patients (84%) and 12/16 (75%) Group B patients and followed up for 15 ± 8 months. During follow-up, 17/21 (81%) patients in Group A and 5/12 (41.7%) in Group B had ILR documentation consistent with reflex syncope. One Group B patient had documented atrioventricular (AV) block and underwent pacemaker implantation. There were no malignant ventricular arrhythmias or deaths on follow-up.
Conclusions:
Reflex syncope is the most common cause of syncope, and accounts for approximately 60% of cases in patients with SHD, negative EPS, and left ventricular (LV) systolic dysfunction with LV ejection fraction (LVEF) >30% and not in heart failure.
Perspective:
The present study showed that about 80% of patients who had a positive HUTT and 50% of patients who had a negative HUTT had findings suggestive of reflex syncope documented on ILR. None of the patients with a negative EPS sustained ventricular arrhythmia or death. This is good news for those who are charged with risk stratification of patients with LVEF >30% and negative EPS, whether HUTT is positive or negative. Notable here are some exclusion criteria, which preclude applicability of the above findings to patients with: AV block documented on electrocardiogram or Holter, bundle branch block, bifascicular or trifascicular block with prolonged HV interval >70 ms, abnormal sinus node function (i.e., corrected sinus node recovery time >550 ms), and ongoing nitrate therapy. While heart failure is not explicitly defined in the manuscript, the requirement that it be absent also further adds potential patients to whom the above findings are not applicable.
Clinical Topics: Arrhythmias and Clinical EP, Heart Failure and Cardiomyopathies, Prevention, Atherosclerotic Disease (CAD/PAD), Implantable Devices, EP Basic Science, SCD/Ventricular Arrhythmias, Atrial Fibrillation/Supraventricular Arrhythmias, Acute Heart Failure
Keywords: Arrhythmias, Cardiac, Atrioventricular Block, Bundle-Branch Block, Cardiomyopathy, Dilated, Coronary Artery Disease, Electrocardiography, Electrophysiology, Heart Failure, Pacemaker, Artificial, Secondary Prevention, Sinoatrial Node, Stroke Volume, Syncope, Tilt-Table Test, Ventricular Dysfunction, Left
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