Relevance of coronary microvascular flow impairment to long-term remodeling and systolic dysfunction in hypertrophic cardiomyopathy.
OBJECTIVE
This study sought to evaluate whether the entity of microvascular dysfunction, assessed by positron emission tomography (PET), predicts the long-term development of left ventricular (LV) remodeling and systolic dysfunction in hypertrophic cardiomyopathy (HCM).


BACKGROUND
A subgroup of patients with HCM developed LV dilation and systolic impairment. A causal role of coronary microvascular dysfunction has been suggested as the underlying pathophysiological mechanism.


METHODS
Fifty-one patients (New York Heart Association functional class I to II) were followed up for 8.1 +/- 2.1 years after measurement of resting and dipyridamole (Dip) myocardial blood flow (MBF). Left ventricular systolic dysfunction was defined as an ejection fraction (LVEF) <50%.


RESULTS
The Dip-MBF was blunted in HCM patients compared with a group of healthy control patients (1.50 +/- 0.69 ml/min/g vs. 2.71 +/- 0.94 ml/min/g; p < 0.001). At final evaluation, 11 patients (22%) had an LVEF <50%; in most (n = 7), systolic dysfunction was associated with a significant increase in LV cavity dimensions (>5 mm) during follow-up. These 11 patients showed lower Dip-MBF than the 40 with preserved LV function (1.04 +/- 0.38 ml/min/g vs. 1.63 +/- 0.71 ml/min/g, respectively; p = 0.001); Dip-MBF was particularly blunted in five patients with clinical progression to severe heart failure symptoms or death (Dip-MBF 0.89 +/- 0.15 ml/min/g). At multivariate analysis, the two independent predictors of systolic dysfunction were Dip-MBF in the lowest tertile (<1.1 ml/min/g; relative hazard, 7.5; p = 0.038) and an end-diastolic LV dimension in the highest tertile (>45 mm; relative hazard, 12.3; p = 0.031).


CONCLUSIONS
Severe microvascular dysfunction is a potent long-term predictor of adverse LV remodeling and systolic dysfunction in HCM. Our findings indicate microvascular dysfunction as a potential target for prevention of disease progression and heart failure in HCM.
Olivotto
Iacopo
I
Regional Referral Center for Myocardial Diseases, Florence, Italy. olivottoi@ao-careggi.toscana.it
Cecchi
Franco
F
Gistri
Roberto
R
Lorenzoni
Roberto
R
Chiriatti
Giampaolo
G
Girolami
Francesca
F
Torricelli
Francesca
F
Camici
Paolo G
PG
D000368:Aged; D002312:Cardiomyopathy, Hypertrophic / Q000150:complications* / Q000503:physiopathology*; D003326:Coronary Circulation; D018450:Disease Progression; D005260:Female; D006801:Humans; D008297:Male; D008833:Microcirculation; D008875:Middle Aged; D011237:Predictive Value of Tests; D012720:Severity of Illness Index; D013599:Systole; D013997:Time Factors; D018487:Ventricular Dysfunction, Left / Q000209:etiology* / Q000503:physiopathology*; D020257:Ventricular Remodeling