Post-Infarction Myocardial Viability and Angina at Everyday Life Activities versus Treadmill Exercise Test
Citation: Post-Infarction Myocardial Viability and Angina at Everyday Life Activities versus Treadmill Exercise Test. American Research Journal of Cardiovascular Diseases, 3(1); pp: 1-12.
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Background: Myocardial viability (VIA) prevalence in post myocardial infarction (MI) patients (pts) in association with angina (ANG) or not has not been prospectively evaluated.
Methods and Findings: Fifty-five post-MI pts with reduced ejection fraction (EF≤40%) underwent stress thallium-201 scintigraphy (Tl-201) viability (VIA) evaluation. ANG at exercise-treadmill-test (ETT) (Borg scale) and at everyday-life (Canadian Cardiovascular Society – CCS) classification was recorded. Groups VIA (29 pts – 53%) vs non-VIA respectively had similar EF (31 ± 7)% vs (33 ± 8)% (NS), higher diseased vessels number 2.8 ± 1.6 vs 1.9 ± 1.3 (p=0.02), CCS 1.7 ± 0.8 vs 1.3 ± 0.6 (p<0.05), CCS≥2 71% vs 41% (p<0.03). Five pts from each group reported ETT ANG (17% vs 21% – NS), with Borg scale 7.7 ± 3.0 vs 7.2 ± 2.4 (NS). CCS≥2 was associated with greater 201Tl reversibility indices within stress defect (p<0.04) or total myocardial mass reversibility (p<0.02). Binary logistics analysis associated VIA positively with number of diseased vessels and negatively with smoking, while CCS≥2 ANG positively with number of diseased vessels. The main limitation is the relatively small number of pts.
Conclusions: Viability, while not significantly correlated to ETT angina, was positively associated only with more frequent everyday-life (CCS) angina. Clinically, in ischemic cardiomyopathy VIA evaluation is indicated, regardless of ANG.
Keywords: Angina pectoris; exercise test; myocardial perfusion imaging; myocardial hibernation
Viability (VIA) in post MI pts with systolic dysfunction is used to evaluate outcomes and determine medical treatment or revascularization (REV). Viable myocardium REV vs medical treatment improves cardiac function and heart failure symptoms and reduces recurrent MI and mortality.1 In the STICH trial, VIA estimation did not improve outcome;2, 3 however, design limitations are outlined, regarding VIA criteria.4
Recent European and American Guidelines recommend REV both for angina (ANG) alleviation and prognosis improvement in ischemic cardiomyopathy.5, 6, 7 Scintigraphy, echocardiography, cardiac magnetic imaging or multidetector computed tomography imaging are used to detect VIA.1, 8
Clinically, ANG is considered indicative of VIA. However, neither prospective nor specific studies have been designed to answer accurately this question.9, 10
Our study is intended to prospectively address ANG accuracy at ETT or everyday-life in predicting VIA.
MATERIAL AND METHODS
Fifty-five post-MI (EF≤40%) ambulatory pts, informed about study aim, were prospectively included and signed informed consent. Fifty two were male (66 ± 10 vs 50 ± 3 years old females). Study protocol conformed to the 1975 Declaration of Helsinki ethical guidelines and was approved by hospital ethics committee.
Mean index-MI-study interval was 12 ± 10 years.
1. Myocardial VIA was assessed by 201Tl myocardial SPECT in two ways:
1.1 Qualitative, based on the official nuclear medicine laboratory assay.
1.2 Quantitative, based on special 3-dimensional perfusion polar maps
1.2.1 Reversible defective proportion of the initial defect (%),
1.2.2 Reversible defective proportion of total myocardial mass (Fig 1)
1.2.3 Objective semiquantitative scores of reversibility (which signifies VIA): Scores SSS (stress-uptake), (SRS) (rest-uptake) and (SDS) between the 2 states for total and individual myocardial segments were calculated using 0 (normal) to 4 (complete) defect grading scale in 20 myocardial segments (Fig 2).11 Hibernation minimum threshold of 20% of the total LV myocardium was used to classify the heart as viable.12, 13