Prognostic Implications of Blunted Feature-Tracking Global Longitudinal Strain During Vasodilator Cardiovascular Magnetic Resonance Stress Imaging

Abstract

Objectives: The purpose of this study was to determine the prognostic value of feature-tracking global longitudinal strain (GLS) measured during vasodilator stress cardiac magnetic resonance (CMR) imaging.

Background: Prior studies have suggested that blunted myocardial strain during dobutamine stress echocardiography may be associated with adverse prognosis. Recent developments in CMR feature-tracking techniques now allow assessment of strain in clinical practice using standard cine images without specialized pulse sequences or complex post-processing. Whether feature-tracking GLS measured during vasodilator stress provides independent and incremental prognostic data is unclear.

Methods: Consecutive patients undergoing stress perfusion CMR were prospectively enrolled (n = 535). Feature-tracking stress GLS was measured immediately after regadenoson perfusion. Patients were followed for major adverse cardiac events (MACE): death, nonfatal myocardial infarction, heart failure hospitalization, sustained ventricular tachycardia, and late revascularization. Cox proportional hazards regression modeling was used to examine the association between stress GLS and MACE. The incremental prognostic value of stress GLS was assessed in nested models.

Results: Over a median follow-up of 1.5 years, 82 patients experienced MACE. By Kaplan-Meier analysis, patients with stress GLS ≥ median (-19%) had significantly reduced event-free survival compared with those with stress GLS < median (log-rank p < 0.001). Stress GLS was significantly associated with risk of MACE after adjustment for clinical and imaging risk factors including ischemia, ejection fraction, and late gadolinium enhancement (hazard ratio: 1.267; p < 0.001). Addition of stress GLS into a model with clinical and imaging predictors resulted in significant increase in the C-index (from 0.80 to 0.85; p = 0.031) and a continuous net reclassification improvement of 0.898 (95% confidence interval: 0.565 to 1.124).

Conclusions: Feature-tracking stress GLS measured during vasodilator stress CMR is an independent predictor of MACE in patients with known or suspected coronary artery disease, incremental to common clinical and imaging risk factors. These findings suggest a role for feature-tracking derived stress GLS in identifying patients at highest risk of adverse events following stress CMR.

Keywords: cardiac magnetic resonance imaging; coronary artery disease; global longitudinal strain; prognosis; stress testing.

Central Illustration.. Kaplan-Meier curves for MACE.

Stratified by stress GLS above and below the median value.

Figure 1.. CMR stress protocol.

Image acquisition sequence. Stress GLS was measured immediately after stress perfusion. LGE = late gadolinium enhancement.

Figure 2.. Relationship between stress GLS and hazard of MACE (with 95% confidence intervals) adjusted to presence of ischemia and LGE.

Hazard ratios are relative to those with median stress GLS.

Figure 3.. Sequential nested Cox models for MACE.

A model based on clinical variables alone was significantly improved by addition of imaging variables (ejection fraction, LGE, ischemia), and further significantly improved by adding stress GLS.