Patients with schizophrenia demonstrate a different cardiovascular risk profile than patients without psychiatric disease, including an elevated heart rate, Fridericia-corrected QT (QTc) prolongation, and pathological Q waves. Additionally, abnormal electrocardiograms (ECGs) are associated with antipsychotics in this population, according to a study published in Schizophrenia Bulletin.

The investigators sought to compare ECG characteristics of patients with schizophrenia against those of matched controls without prior psychiatric diseases or psychotropic drug use. In addition, the investigators explored the association of redeemed psychotropic drug prescriptions with abnormal ECGs.

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The study included 4486 patients with schizophrenia from a Danish cross-sectional study who were matched 1:5 by age, gender, and ECG recording year to 22,430 controls without prior psychiatric diagnoses or psychotropic drug use. The investigators assessed first-time digital ECGs recorded between 2001 and 2015 for measures of heart rate, P-wave duration, PR interval, QRS duration, QT interval, and QTc interval. Redeemed prescriptions of psychotropic drugs (antipsychotics, antidepressants, lithium, and benzodiazepines) within 180 days before ECG recording were identified using the Danish National Prescription Register. Additional redeemed prescriptions were used to define comorbidities. Logistic regression modeling was used to analyze the association of individual redeemed psychotropic drug prescriptions with abnormal ECGs.

Abnormal ECG results were similarly prevalent among both schizophrenia and control groups (54% vs 54.5%; P =.536); however, patients with schizophrenia had a higher median heart rate compared with controls (79 [68-91] vs 69 [61-77] beats per minute; <.001). The QTc interval was also higher among patients with schizophrenia vs controls (416 [402-431] vs 412 [400-425] ms; P <.001), as was the prevalence of QTc prolongation (3.4% vs 1.1%; P <.001) and pathological Q waves (5.3% vs 3.9%; P <.001). Compared with controls, patients with schizophrenia less frequently met criteria for left ventricular hypertrophy (6.1% vs 9.6%; P <.001) or atrial fibrillation or flutter (0.7% vs 1.4%; P <.001). Abnormal ECGs were associated with redeemed antipsychotic prescriptions only among patients with schizophrenia (odds ratio 1.20; 95% CI, 1.04-1.39).

A limitation to the study included the lack of data on ECG indications, lifestyle behaviors, anthropometric measurements, blood samples relative to ECG recordings, disease severity, medication adherence, or changes in prescribing patterns, which may lead to residual or unaccounted confounding. Furthermore, the impact of each abnormal ECG on outcomes was beyond the study scope.

The investigators suggest that patients with schizophrenia have a different cardiovascular risk profile than patients without psychiatric disease: they exhibit an elevated heart rate, QTc prolongation, and pathological Q waves and less often experienced left ventricular hypertrophy and atrial fibrillation or flutter. Abnormal ECGs associated with antipsychotic use further highlights the need for an integrated approach to care in this population.

Reference
Polcwiartek C, Kragholm K, Hansen SM, et al. Electrocardiogram characteristics and their association with psychotropic drugs among patients with schizophrenia [published online June 20, 2019]. Schizophr Bull. doi: 10.1093/schbul/sbz064