Efficacy of coronary angioplasty for the treatment of hibernating myocardium

Abstract

Objectives: To determine the efficacy of coronary angioplasty as the sole method of revascularisation in patients with coronary artery disease and chronically dysfunctional but viable myocardium (hibernating myocardium), and to assess the effect of restenosis on functional outcome.

Design and patients: 24 consecutive patients with hibernating myocardium were studied. Positron emission tomography was used to assess myocardial viability, blood flow, and flow reserve. One patient refused angioplasty, one had bypass surgery, and one died while waiting for an elective procedure. The procedure failed in three patients. The remaining 18 patients had repeat echocardiography, 15 had repeat coronary angiography, and nine had repeat assessments of blood flow and flow reserve at mean (SD) 17 (2) weeks after angioplasty. In three patients restenosis was documented.

Results: The wall motion score index in the revascularised territories improved from 1.71 (0.37) to 1.34 (0.47) (p = 0.008). Thirty of 51 dysfunctional segments improved in territories without restenosis compared with three of 14 in restenosed territories (p = 0.001). Hibernating and normal segments had comparable flows (0.82 (0.26) v 0.89 (0.24) ml/min/g; NS) while flow reserve was lower in hibernating segments (1.55 (0.68) v 2.07 (1.08); p = 0.03). In segments without restenosis flow reserve improved from 2.03 (1.25) to 2.33 (1.4) (p = 0.03). Sensitivity, specificity, and positive and negative predictive accuracy of the viability study were 97%, 77%, 82%, and 96%, respectively. After excluding patients with restenosis, specificity and positive predictive accuracy improved to 90% and 93%.

Conclusions: Angioplasty improves function in hibernating myocardium, and restenosis prevents recovery; hibernating myocardium is characterised by an impairment of flow reserve; restenosis affects the diagnostic accuracy of viability studies.

Figure 1

Schematic representation of study protocol. LV, left ventricle; ECHO, echocardiography; FDG, ¹⁸F-fluorodeoxyglucose; MBF, myocardial blood flow; PET, positron emission tomography; PTCA, percutaneous transluminal coronary angioplasty.

Figure 2

Chart showing comparison of changes in function in revascularised versus non-revascularised dysfunctional segments in the 15 patients who underwent percutaneous transluminal coronary angioplasty and follow up angiography.

Figure 3

Changes in global and regional wall motion score index (WMSI) after percutaneous transluminal coronary angioplasty (PTCA).

Figure 4

Diminishing ¹⁸F-fluorodeoxyglucose (FDG) uptake with increasing severity of wall motion abnormality.

Figure 5

A receiver-operator characteristic (ROC) curve showing sensitivity and specificity in identifying hibernating segments for different values of metabolic rate of glucose (MRG) in µmol/g/min. The large dot represents the operating point associated with the best compromise between sensitivity and specificity.