4936Cardiac magnetic resonance strain analysis predicts functional recovery following acute ST-segment elevation myocardial infarction

Background

Late gadolinium enhancement (LGE) is the clinical reference standard for estimation of infarct extension and prediction of functional recovery following reperfused acute ST-segment elevation myocardial infarction (STEMI). Nevertheless, myocardial edema, microvascular obstruction and intramyocardial hemorrhage as well as the timing of image acquisition after contrast administration may influence the extent of LGE and underestimate the potential for recovery. Dobutamine stress testing has been recommended to more accurately predict functional recovery when infarct transmurality is between 25 to 75%. We hypothesized that cardiac magnetic resonance (CMR) tissue tracking strain analysis may provide additional value to LGE for the prediction of functional recovery.

Methods

In 370 patients with STEMI who underwent successful primary percutaneous revascularization and were studied with CMR within 3–5 days of the event, peak systolic longitudinal (LS), circumferential (CS) and radial (RS) strain were analyzed with routine SSFP images of 3 long-axis and a stack of short-axis slices (Tissue Tracking, CVI42®, Figure panel A and B). Inversion-recovery echogradient sequences were analyzed 20 minutes after contrast administration for LGE transmurality (Panel C). All per-segment analysis was performed according to the AHA 16-segment model. CMR was repeated at 6 months and functional recovery was defined as persistent normokinesia or improvement of wall motion score from baseline to 6-month CMR.

Results

At baseline CMR, of a total of 5920 segments 70.4% were normokinetic, 7.2% were hypokinetic, 21.9% were akinetic and 0.6% were dyskinetic. All strain parameters decreased significantly with worsening wall motion. At follow-up, 81.5% of the segments showed functional recovery. All strain parameters were significantly associated with functional recovery (p<0.001) and showed higher predictive value for improvement of wall motion than LGE transmurality (ROC AUC 0.713 LS, 0.710 CS, 0.683 RS and 0.660 LGE). For basal CMR dysfunctional segments, a CS <−10.7% showed the highest accuracy (66%) to predict wall motion improvement, with 58% sensitivity, 76% specificity, 75% positive predictive value (PPV) and 59% negative predictive value (NPV). These results were comparable to LGE transmurality <50% (65% accuracy, 59% sensitivity, 73% specificity, 74% positive predictive value and 58% negative predictive value). Nevertheless, adding CS analysis to a 50% LGE transmurality cutoff was the best combination for prediction of functional recovery and increased the overall accuracy to 70%, with 76% sensitivity, 64% specificity, 65% PPV and 75% NPV.

CS analysis in an inferior STEMI

Conclusions

Acute CMR tissue tracking strain analysis complements LGE assessment for prediction of functional recovery following an STEMI. The combination of LGE infarct transmurality under 50% and a CS strain higher than −10.7% showed the highest accuracy for prediction of recovery of function.

Matrix metalloproteinase-1 and its inhibitor, TIMP-1, in systolic heart failure: relation to functional data and prognosis

BACKGROUND

Structural remodelling of left ventricle is a common feature in the progression of congestive heart failure (CHF). Matrix metalloproteinases (MMPs) have been directly implicated as they degrade extracellular proteins. To test the hypothesis that MMP-and its inhibitor, tissue type inhibitor of matrix metalloproteinases (TIMP-1), could be related to functional status and prognosis in CHF, we examined the relationship of MMP-1 and TIMP-1 to peak oxygen consumption (VO2) and peak minute ventilation/carbon dioxide production relationship (VE/VCO2), and assessed their prognostic value.

METHODS

We studied 50 patients with CHF, who were compared with 53 controls echocardiogram and ergoespirometry were performed, and serum levels of MMP-1 and TIMP-1 were assayed by ELISA. Patients were followed up for 17.5+/-8.9 months, and total mortality, readmissions for heart failure and cardiac transplantation were recorded.

RESULTS

Patients with CHF had lower levels of MMP-1 (P=0.027), and higher levels of TIMP-1 and TIMP-1/MMP-1 ratio (both P<0.01) than controls. TIMP-1 levels and the TIMP-1/MMP-1 ratio correlated negatively with peak VO2 (Spearman, r:-0.51; P=0.001 and r: -0.42; P=0.030, respectively). During the follow-up period, 23 patients (47.9%) suffered endpoints--these patients had higher baseline peak VE/VCO2 (P=0.001), TIMP-1 (P=0.004), and TIMP-1/MMP-1 ratio values (P=0.002), whereas MMP-1 levels were lower (P=0.027). On multivariate analysis, VE/VCO2, MMP-1 levels and age were the only variables independently related to prognosis (all P<0.05).

CONCLUSION

Poor functional capacity in CHF can be related to abnormal extracellular matrix turnover. Patients who suffered endpoints had more abnormal indices of matrix turnover, where MMP-1 levels showed independent prognostic value.