Comparison of quantitative coronary angiography and first-pass perfusion magnetic resonance imaging for the detection of an impaired coronary perfusion in nonsevere coronary stenosis

Relation of Myocardial Perfusion Reserve and Left Ventricular Ejection Fraction in Ischemic and Nonischemic Cardiomyopathy

Quantification of myocardial perfusion reserve (MPR) using vasodilator stress cardiac magnetic resonance is increasingly used to detect coronary artery disease. However, MPR can also be altered because of changes in microvascular function. We aimed to determine whether MPR can distinguish between ischemic cardiomyopathy (IC) secondary to coronary artery disease and non-IC (NIC) with microvascular dysfunction and no underlying epicardial coronary disease. A total of 60 patients (mean age 65 ± 14 years, 30% women), including 31 with IC and 29 with NIC, were identified from a pre-existing vasodilator stress cardiac magnetic resonance registry. Short-axis cine slices were used to measure left ventricular ejection fraction (LVEF) using the Simpson method of disks. MPR index (MPRi) was determined from first-pass myocardial perfusion images during stress and rest using the upslope ratio, normalized for the arterial input and corrected for rate pressure product. Patients in both groups were divided into subgroups of LVEF ≤35% and LVEF >35%. Differences in MPRi between the subgroups were examined. MPRi was moderately correlated with LVEF in patients with NIC (r = 0.53, p = 0.03), whereas the correlation in patients with IC was lower (r = 0.32, p = 0.22). Average LVEF in NIC and IC was 34% ± 8% and 35% ± 8%, respectively (p = 0.63). MPRi was not significantly different in IC compared with NIC (1.17 [0.88 to 1.61] vs 1.23 [1.07 to 1.66], p = 0.41), including the subgroups of LVEF (IC: 1.20 ± 0.56 vs NIC: 1.15 ± 0.24, p = 0.75 for LVEF ≤35% and IC: 1.35 ± 0.44 vs NIC: 1.58 ± 0.50, p = 0.19 for LVEF >35%). However, MPRi was significantly lower in patients with LVEF ≤35% compared with those with LVEF>35% (1.17 ± 0.40 vs 1.47 ± 0.47, p = 0.01). Similar difference between LVEF groups was noted in the patients with NIC (1.15 ± 0.24 vs 1.58 ± 0.50, p = 0.006) but not in the patients with IC (1.20 ± 0.56 vs 1.35 ± 0.44, p = 0.42). MPRi can be abnormal in the presence of left ventricular dysfunction with nonischemic etiology. This is a potential pitfall to consider when using this approach to detect ischemia because of epicardial coronary disease using myocardial perfusion imaging.

Cardiac magnetic resonance imaging myocardial perfusion reserve index assessment in women with microvascular coronary dysfunction and reference controls

OBJECTIVE

We sought to comparatively assess cardiac magnetic resonance imaging (CMRI) myocardial perfusion reserve index (MPRI) in women with confirmed microvascular coronary dysfunction (MCD) cases and reference control women.

BACKGROUND

Women with signs or symptoms of myocardial ischemia in the absence of obstructive coronary artery disease (CAD) frequently have MCD which carries an adverse prognosis. Diagnosis involves invasive coronary reactivity testing (CRT). Adenosine CMRI is a non-invasive test that may be useful for the detection of MCD.

METHODS

Fifty-three women with MCD confirmed by CRT and 12 age- and estrogen-use matched reference controls underwent adenosine CMRI. CMRI was assessed for MPRI, calculated using the ratio of myocardial blood flow at hyperemia/rest for the whole myocardium and separately for the 16 segments as defined by the American Heart Association. Statistical analysis was performed using repeated measures ANOVA models.

RESULTS

Compared to reference controls, MCD cases had lower MPRI values globally and in subendocardial and subepicardial regions (1.63±0.39 vs. 1.98±0.38, P=0.007, 1.51±0.35 vs. 1.84±0.34, P=0.0045, 1.68±0.38 vs. 2.04±0.41, P=0.005, respectively). A perfusion gradient across the myocardium with lower MPRI in the subendocardium compared to the subepicardium was observed for both groups.

CONCLUSIONS

Women with MCD have lower MPRI measured by perfusion CMRI compared to reference controls. CMRI may be a useful diagnostic modality for MCD. Prospective validation of a diagnostic threshold for MPRI in patients with MCD is needed.

Ranolazine improves angina in women with evidence of myocardial ischemia but no obstructive coronary artery disease

OBJECTIVES

We conducted a pilot study for a large definitive clinical trial evaluating the impact of ranolazine in women with angina, evidence of myocardial ischemia, and no obstructive coronary artery disease (CAD).

BACKGROUND

Women with angina, evidence of myocardial ischemia, but no obstructive CAD frequently have microvascular coronary dysfunction. The impact of ranolazine in this patient group is unknown.

METHODS

A pilot randomized, double-blind, placebo-controlled, crossover trial was conducted in 20 women with angina, no obstructive CAD, and ≥ 10% ischemic myocardium on adenosine stress cardiac magnetic resonance (CMR) imaging. Participants were assigned to ranolazine or placebo for 4 weeks separated by a 2-week washout. The Seattle Angina Questionnaire and CMR were evaluated after each treatment. Invasive coronary flow reserve (CFR) was available in patients who underwent clinically indicated coronary reactivity testing. CMR data analysis included the percentage of ischemic myocardium and quantitative myocardial perfusion reserve index (MPRI).

RESULTS

The mean age of subjects was 57 ± 11 years. Compared with placebo, patients on ranolazine had significantly higher (better) Seattle Angina Questionnaire scores, including physical functioning (p = 0.046), angina stability (p = 0.008), and quality of life (p = 0.021). There was a trend toward a higher (better) CMR mid-ventricular MPRI (2.4 [2.0 minimum, 2.8 maximum] vs. 2.1 [1.7 minimum, 2.5 maximum], p = 0.074) on ranolazine. Among women with coronary reactivity testing (n = 13), those with CFR ≤ 3.0 had a significantly improved MPRI on ranolazine versus placebo compared to women with CFR > 3.0 (Δ in MPRI 0.48 vs. -0.82, p = 0.04).

CONCLUSIONS

In women with angina, evidence of ischemia, and no obstructive CAD, this pilot randomized, controlled trial revealed that ranolazine improves angina. Myocardial ischemia may also improve, particularly among women with low CFR. These data document approach feasibility and provide outcome variability estimates for planning a definitive large clinical trial to evaluate the role of ranolazine in women with microvascular coronary dysfunction. (Microvascular Coronary Disease In Women: Impact Of Ranolazine; NCT00570089).