Continuous ST-Monitoring Function of Implantable Cardioverter Defibrillator Detects Silent Ischemia in Patients With Coronary Artery Disease

Abstract

Background: Newer implantable cardioverter defibrillators can monitor intracardiac ECGs , but their ability to detect ischemia is unclear. This study investigated the usefulness of implantable cardioverter defibrillators with an ST-monitoring function in coronary artery disease patients.

Methods and results: We conducted a prospective study of implantable cardioverter defibrillator patients with the ST-monitoring function. One hundred seventy-three patients who received implantable cardioverter defibrillators for primary or secondary prevention of sudden cardiac death. All patients underwent medical examinations at least every 6 months, with standard 12-lead ECGs and device checks that included analysis of the ST-monitoring function. Myocardial perfusion imaging or coronary angiography was performed during the follow-up. The mean follow-up duration was 23.3±7.7 months. Significant ST changes occurred in 15 patients (8.7%), of whom 14 were asymptomatic. The incidence of angina pectoris was significantly higher in the ST change (+) group than that in the ST change (-) group (28.6% versus 7.2%, P=0.03). In the patients who underwent myocardial perfusion imaging, the sensitivity, specificity, and negative predictive value of the ST-monitoring feature to detect ischemia were 75.0%, 72.5%, and 93.5%, respectively. The sensitivity, specificity, and negative predictive value of the ST-monitoring feature to predict residual stenosis evaluated using coronary angiography were 76.9%, 83.5%, and 97.5%, respectively. The percentage of patients with a septal right ventricular lead was significantly lower in the ST change (+) group than in the ST change (-) group (13.5% versus 33.5%, P=0.01).

Conclusions: If intracardiac ECGs ST changes are detected, it is necessary to use additional modalities even in asymptomatic patients.

Clinical trial registration: URL: upload.umin.ac.jp. Unique identifier: UMIN000011824.

Keywords: coronary artery disease; implantable cardioverter‐defibrillator; ischemia.

Figure 1

ST‐monitoring feature of the implantable cardioverter defibrillator (ICD). Monitoring of the ST segment using the ICD, with an intracoronary electrogram from the ICD can to right ventricular tip lead.

Figure 2

IntracardiacECG episode in the case described. ST depression was recorded using the intracardiac ECG monitoring. The upper panel shows the intracardiac ECG at baseline, the middle panel shows the ST shift onset, and the lower panel shows the maximum ST shift. The patient had no symptoms at that time.

Figure 3

Myocardial perfusion imaging in the case described. ^99mTc‐myocardial single‐photon emission computed tomography (SPECT) was performed. The image on the left is the stress image, and the image on the right is the rest image. ^99mTc‐myocardial SPECT reveals an ischemic region from the septum to the apex.

Figure 4

Cardiac catheterization in the case described. A, Multiple mild to moderate stenoses are recognized in the right coronary artery (left anterior oblique [LAO] 45, cranial [CRA] 0). B, Coronary angiogram demonstrates severe stenosis (arrow) at the ostium of the left anterior descending artery (LAD) (LAO 50, caudal 30). C, A drug‐eluting stent (Xience 3.25×12 mm) was implanted from the left main trunk to the LAD ostium. D, After the stent treatment, the severe LAD stenosis disappeared (arrowhead). After the procedure, the patient was free from any further chest discomfort and no further ST depression was recorded using intracoronary electrogram monitoring.