Page 53 - Coronary hemodynamics in acute myocardial infarction - Matthijs Bax

Microvascular resistance of infarct and noninfarct coronary arteries
Unrelated nonparametric variables were tested with Mann-Whitney U statistic test, and related nonparametric variables with Wilcoxon’s signed-rank test. Categorical variables were compared by chi-square or Fisher’s exact test, where appropriate. A p value <0.05 was considered statistically significant. Statistical analysis was performed with SPSS 11.5 (SPSS, Inc., Chicago, Illinois).
Results 3
Patients’ baseline characteristics are listed in Table 2.
A time-dependent improvement of CFVR in IRAs and non-IRAs remained significant after correction for the rate–pressure product (Table 1). Uncorrected and corrected baseline average peak blood flow velocities in IRAs were higher than those in non-IRAs after angioplasty (p <0.01) and at 1-week follow-up (p <0.01). However, at 6-month follow-up, uncorrected and corrected baseline average peak blood flow velocities in IRAs equaled values in non-IRAs. Baseline average peak blood flow velocity in non-IRAs did not change in 6 months. However, after correction for the rate–pressure product, baseline average peak blood flow velocities at 1 week and 6 months were lower than immediately after angioplasty in IRAs and non-IRAs (Table 1; baseline average peak blood flow velocity in nonstenosed arteries in patients without infarctions was 18 cm/second, range 6 to 26).15
Hyperemic average peak blood flow velocity was decreased after angioplasty and significantly improved at follow-up in IRAs and non-IRAs (Table 1; hyperemic average peak blood flow velocity in nonstenosed arteries in patients without infarct was 49 cm/second, range 25 to 84).15
At follow-up, improvement of CFVR in IRAs and non-IRAs was primarily attributable to an increase in hyperemic average peak blood flow velocity. At the time of AMI, baseline microvascular resistance in IRAs did not differ from that in non-IRAs. Baseline microvascular resistance in the 2 artery types decreased at 1-week follow-up and increased at 6 months (in nonstenosed arteries in patients without infarct, baseline microvascular resistance is 6.5 mm Hg/cm/second, range 3.3 to 13.2).15
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