Student: Courteney Hore
Supervisors: Suzanne Pitama, Vicky Cameron, John Irvine
Sponsor: Maurice & Phyllis Paykel Trust
This studentship was designed to complement the Hauora Manawa Project, a larger project that is investigating the prevalence of cardiovascular disease (CVD) in a Maori community. The first stage of the project focused on a rural Maori population in Wairoa in the Hawkes Bay. The second stage will focus on an urban Maori population in Christchurch, along with an age and gender matched non-Maori population. This studentship was based on the 253 completed electrocardiograms (ECGs) from the Wairoa community, which were used to investigate the presence of left ventricular hypertrophy (LVH), which is thickening of the muscle of the left ventricle of the heart. An ECG provides a record of the electrical activity of the heart over time. Certain parts of the recording show changes when LVH is present. It is a marker of heart disease and an independent risk factor for CVD, which if detected early may be monitored and treated to slow eventual progression of heart disease.
To determine the ability of ECGs to detect LVH compared with the gold standard, echocardiography (ECHO), an imaging technique designed to assess heart function, and hence to assess the effectiveness of an ECG as a diagnostic tool in primary health care in a community setting.
A standard form was designed for entering the ECG measurements, with recognised criteria for LVH defined, to enable uniform and consistent analysis of the ECGs. Initial ECG measurements taken by the student were independently read and corroborated by the project supervisors as a form of quality control. For each study participant, LVH was identified as present/not according to the established criteria. This information was then compared with that collated by specialists analysing the ECHOs for LVH.
From the sample population of 253 participants, 16.2% of the ECGs detected LVH, compared with 21.7% of the ECHOs. Further analysis showed that only one third of those participants who had a positive ECHO also had a positive ECG. Conversely, almost 90% of those that had a negative ECHO had a negative ECG. Several other statistical tests demonstrated a consistent inability to reliably detect LVH upon comparing the ECG with the gold standard ECHO.
ECG analysis did not prove to be highly effective in detecting LVH. While it may not be effective without other clinical information to support it, ECG may still prove useful in a community setting as part of a complete assessment to identify risk factors for CVD. This may be more significant in a community setting where access to echocardiography may be a significant issue.