Objective: To assess the prevalence and the characteristics of silent myocardial ischaemia (SMI) and ventricular arrhythmias (VA) in subjects with Alzheimer's disease (AD) and mild cognitive impairment (MCI) and their relationships with QT interval dispersion (QTD).
Methods: Thirty-three subjects with AD, 39 subjects with MCI, and 29 cognitive healthy control subjects matched for demographic characteristics, hypertensive condition, smoking habits, and laboratory parameters were enrolled. Each subject underwent clinical and cognitive examination, a structural brain imaging study, electrocardiogram (ECG), 24-h ECG recording, 24-h blood pressure monitoring, and echocardiogram. Detection and characterization of QT dispersion, SMI and VA were performed.
Results: The three groups were comparable regarding demographic and basal cardiovascular characteristics: notwithstanding this, SMI episodes were observed only in AD and MCI patients (19 and 14, respectively). A significantly greater prevalence of repetitive ventricular premature beats was observed in AD (mean 8.56+/-13.1) and in MCI (1.8+/-7.2) vs. control (0.7+/-1.7). The QTD, the ischaemic burden and the number of repetitive ventricular beats revealed to be significantly related.
Conclusions: Increased prevalence of SMI and potentially ominous VA were found in AD and, to a lesser extent, in MCI. SMI and repetitive VA were significantly related with QTD. These findings could be related to an increased risk of sudden cardiac death in AD and MCI patients.