Clinical outcomes of overlapping versus non-overlapping everolimus-eluting absorb bioresorbable vascular scaffolds: An analysis from the multicentre prospective RAI registry (ClinicalTrials.gov identifier: NCT02298413).

OBJECTIVES: To compare clinical outcomes of patients treated with overlapping versus non-overlapping Absorb BVS. BACKGROUND: Limited data are available on the clinical impact of stent overlap with the Absorb BVS bioresorbable stent. METHODS: We compared outcomes of patients receiving overlapping or non-overlapping Absorb BVS in the multicenter prospective RAI Registry. RESULTS: Out of 1,505 consecutive patients treated with Absorb BVS, 1,384 were eligible for this analysis. Of these, 377 (27%) were in the overlap group, and 1,007 (73%) in the non-overlap group. The most frequent overlap configuration was the marker-to-marker type (48%), followed by marker-over-marker (46%) and marker-inside-marker (6%) types. Patients of the overlap group had higher prevalence of multivessel disease and higher SYNTAX score, and required more frequently the use of intravascular imaging. At a median follow-up of 368 days, no difference was observed between overlap and non-overlap groups in terms of a device-related composite endpoint (cardiac death, TV-MI, ID-TLR) (5.8% vs. 4.1%, P = 0.20) or of a patient-related composite endpoint (any death, any MI, any revascularization) (15.4% vs. 12.5%, P = 0.18). Cardiac death (1.0% vs. 1.3%, P = 0.54), MI (4.5% vs. 3.6%, P = 0.51), TVR (4.5% vs. 3.6%, P = 0.51) and stent thrombosis (1.1 vs. 1.5%, P = 1.00) were also comparable between groups. When assessing outcomes of the overlap population according to overlap configurations used, no difference was observed in terms of the device- or patient-related composite endpoints. CONCLUSIONS: Outcomes of patients with or without overlapping BVS were comparable at mid-term follow-up despite higher angiographic complexity of the overlap subset. © 2017 Wiley Periodicals, Inc.

Post-procedural hemodiafiltration in acute coronary syndrome patients with associated renal and cardiac dysfunction undergoing urgent and emergency coronary angiography.

OBJECTIVES: We investigated the use of a 3-hr treatment with hemodiafiltration, initiated soon after emergency or urgent coronary angiography in acute coronary syndrome (ACS) patients with associated severe renal and cardiac dysfunction. BACKGROUND: Patients with ACS and severe combined renal and cardiac dysfunction have a particularly high mortality risk. In them, the ideal strategy to both optimize treatment of coronary disease and minimize renal injury risk is currently unknown. METHODS: This was an interventional study. ACS patients (STEMI and NSTEMI) with associated severe renal (eGFR ≤30 ml/min/1.73 m(2) ) and cardiac (LVEF ≤40%) dysfunction, admitted at La Spezia Hospital <24 hr from symptoms onset, underwent a prophylactic 3-hr hemodiafiltration treatment, which was started soon after urgent or emergency coronary procedure. Controls were patients matched for age, gender, Mehran's risk score, and kind of ACS, admitted at the Centro Cardiologico Monzino Milan. In-hospital and 1-year outcomes were evaluated. RESULTS: Sixty patients (30% STEMI), 30 hemodiafiltration-treated patients and 30 controls, with similar baseline characteristics, were included. In-hospital and cumulative 1-year mortality rates were significantly lower in hemodiafiltration-treated patients than in controls (3% vs. 23%; P = 0.05, and 10% vs. 53%; P < 0.001, respectively). Moreover, they had a lower incidence of severe AKI (10% vs. 40%; P = 0.015) and lower need for rescue renal replacement therapy during hospitalization (7% vs. 27%; P = 0.04). CONCLUSIONS: Our pilot study suggests that, in ACS patients with severe renal and cardiac insufficiency, treatment with an aggressive prophylactic hemodiafiltration session after urgent or emergency coronary angiography seems to be associated with a relevant improvement in survival.

Fractional flow reserve in patients with type 1 or type 2 non-ST elevation acute myocardial infarction.

AIMS: We assessed a combined strategy of fractional flow reserve (FFR) plus angiography in stratifying cardiovascular risk in patients with type 1 myocardial infarction (T1MI) or type 2 (T2MI) non-ST elevation acute myocardial infarction (NSTEMI). METHODS: A cohort of 150 NSTEMI patients were prospectively studied. Clinical and angiographic features guided the identification of T1MI vs T2MI and the treatment of culprit lesions. Subsequently, T1MI patients underwent FFR evaluation of nonculprit stenoses. In T2MI patients all angiographically significant stenoses were evaluated by FFR. FFR < 0.80 was an indication for revascularization. Based on FFR results, two groups were compared: patients with all lesions ≥0.80 ('defer' group, n = 87) and those with at least one lesion <0.80 ('perform' group, n = 63). The primary end point was the composite of all-cause death, nonfatal MI and unplanned coronary revascularization. RESULTS: Median clinical follow-up was of 35 months (interquartile range 14-44). Primary end-point rates in the 'defer' and 'perform' groups were 14.5% and 30.0% at 12 months and 28% and 46% at 36 months, respectively (log-rank test: at 1 year, P = 0.007; at the end of follow-up P = 0.014). On multivariable analysis, chronic kidney disease (HR 3.50, 95% CI: 1.89-6.46, P = 0.0001) and FFR group ('perform' vs 'defer': HR 1.75 95% CI: 1.01-3.04, P = 0.046) were independent predictors of adverse events. CONCLUSIONS: In NSTEMI patients, our results indicated that FFR combined with angiography allowed the treatment of nonfunctional significant lesions to be safely deferred and patient cardiovascular risk to be identified.

Effectiveness of the transradial approach to reduce bleedings in patients undergoing urgent coronary angioplasty with GPIIb/IIIa inhibitors for acute coronary syndromes.

OBJECTIVES: To analyze the effectiveness of the transradial approach in reducing bleeding rates following urgent percutaneous coronary intervention (PCI) in patients with acute coronary syndromes treated with glycoprotein IIb/IIIa inhibitors (GPIs). BACKGROUND: PCI and use of GPIs are recommended in acute coronary syndromes, but are strong predictors of severe hemorrhagic complications, which, in turn, are associated with reduced survival. The transradial approach represents a simple and effective solution to reduce vascular access site bleedings, particularly with GPIs. METHODS: All consecutive patients undergoing urgent transradial PCI under GPI treatment were enrolled in the registry. No patients were excluded. In addition, we performed a case-matched comparison of the transradial versus transfemoral approach using propensity analysis to adjust for known risk factors for bleeding. The primary end point was the rate of bleedings, graded according to the Thrombolysis in Myocardial Infarction (TIMI) classification. RESULTS: Five hundred thirty-one consecutive patients were prospectively enrolled in the registry. TIMI major, minor, and minimal bleedings were 0.2%, 1.7%, and 6.4%, respectively. Transfusion rate was 0.8%. After propensity-matched analysis, the transradial approach was associated with significantly lower rates of all types of bleedings, while the transfemoral approach was the strongest predictor of TIMI major/minor bleedings (odds ratio 6.67; 95% confidence interval 1.72-25; P = 0.006). CONCLUSIONS: The transradial approach dramatically reduces access site bleedings, including TIMI major and minor bleedings, and transfusion rate, while preserving procedural success and clinical outcome. The transradial approach is an attractive solution to reduce bleeding complications in patients treated with GPIs.

"Full-plastic jacket" with everolimus-eluting Absorb bioresorbable vascular scaffolds: Clinical outcomes in the multicenter prospective RAI registry (ClinicalTrials.gov Identifier: NCT02298413).

OBJECTIVES: The objective of this study was to investigate mid-term clinical outcomes of patients treated with 'full-plastic jacket' (FPJ) everolimus-eluting Absorb bioresorbable vascular scaffold (BRS) implantation. BACKGROUND: FPJ with BRS may represent an interesting option for patient with diffuse coronary artery disease (CAD), but data on the clinical impact of FPJ using the Absorb BRS are scant. METHODS: FPJ was defined as the implantation of >56 mm of overlapping BRS in at least one vessel. We compared outcomes of patients receiving Absorb FPJ vs. non-FPJ within the multicenter prospective RAI Registry. RESULTS: Out of 1505 consecutive patients enrolled in the RAI registry, 1384 were eligible for this analysis. Of these, 143 (10.3%) were treated with BRS FPJ. At a median follow-up of 649 days, no differences were observed between FPJ and non-FPJ groups in terms of the device-oriented composite endpoint (DoCE) (5.6% vs. 4.4%, p = 0.675) or the patient-related composite endpoint (PoCE) (20.9% vs. 15.9%, p = 0.149). Patients receiving FPJ had higher rates of target vessel repeat revascularization (TVR) (11.2% vs. 6.3%, p = 0.042). In the FPJ group, there was no cardiac death and only one (very late) stent thrombosis (ST) (0.7%). CONCLUSIONS: Mid-term outcomes of a FPJ PCI strategy in the setting of diffuse CAD did not show a significant increase in composite device- and patient-related events, with rates of cardiac death and ST comparable to non-FPJ Absorb BRS implantation. However, these findings are hypothesis generating and requiring further validation.

Clinical findings after bioresorbable vascular scaffold implantation in an unrestricted cohort of patients with ST-segment elevation myocardial infarction (from the RAI registry).

BACKGROUND: The bioresorbable vascular scaffold (BVS) technology may be an appealing option in ST-segment elevation myocardial infarction (STEMI) patients. However, the available evidence on its use in this challenging subset is limited. METHODS: Registro Absorb Italiano (RAI) is a multicenter, prospective registry that aims to assess BVS performance through a 5-year follow-up of all consecutive patients who undergone at least 1 successful BVS implantation. As a part of it, a subgroup analysis in STEMI patients was performed and the outcomes of this cohort compared to the remaining population (defined as "non-STEMI") are reported here. RESULTS: Among the 1505 patients enrolled, 317 (21.1%) had STEMI on admission. Among those, 232 (73.2%) underwent primary percutaneous coronary intervention (PCI) within 12 h from symptom onset; 64 (20.2%) were late-comers (>12 h); 16 (5%) underwent PCI after successful thrombolysis while 5 (1.6%) underwent rescue-PCI. At a median follow-up time of 12 months (IQR 6-20 months) no differences were noticed between STEMI and "non-STEMI" groups in terms of device-oriented composite endpoint (4.1% vs. 5.6%; p = 0.3) and its singular components: ischemia-driven target lesion revascularization (3.2% vs. 3.6%; p = 0.7), target-vessel myocardial infarction (3.2% vs. 2.8%; p = 0.7) and cardiac death (0.6% vs. 0.6%; p = 0.9). The rate of definite/probable scaffold thrombosis (ScT) was numerically higher but not significant in the STEMI group (2.5% vs. 1.3%; p = 0.1). CONCLUSIONS: BVS implantation in an unrestricted cohort of STEMI patients is associated with a numerically higher rate of ScT compared to the non-STEMI group. Further studies exploring the potential clinical impact of a pre-specified BVS implantation strategy in this high-risk clinical setting are needed.

Coronary microvascular dysfunction and prognosis in hypertrophic cardiomyopathy.

BACKGROUND: Microvascular dysfunction, reflected by an inadequate increase in myocardial blood flow in response to dipyridamole infusion, is a recognized feature of hypertrophic cardiomyopathy. Its long-term effect on the prognosis is unknown. We prospectively evaluated a cohort of patients with hypertrophic cardiomyopathy after they had undergone quantitative assessment of myocardial blood flow by positron-emission tomography (PET). METHODS: Fifty-one patients (New York Heart Association class I or II) were followed for a mean (+/-SD) of 8.1+/-2.1 years after PET. Twelve subjects with atypical chest pain served as controls. Measurement of flow was performed at base line and after the infusion of the coronary vasodilator dipyridamole, with the use of nitrogen-13-labeled ammonia. Patients were then divided into three equal groups with increasing values of myocardial blood flow. RESULTS: The response of myocardial blood flow to dipyridamole was severely blunted in the patients, as compared with the controls (1.50+/-0.69 vs. 2.71+/-0.94 ml per minute per gram of tissue, P<0.001). Sixteen patients (31 percent) had an unfavorable outcome (death from cardiovascular causes, progression to New York Heart Association class III or IV, or sustained ventricular arrhythmias requiring the implantation of a cardioverter-defibrillator) 2.2 to 9.1 years after PET. Reduced blood flow in response to dipyridamole was strongly associated with an unfavorable outcome. Multivariate analysis showed that among patients in the lowest of the three flow groups the age-adjusted relative hazard of death from cardiovascular causes was 9.6 (P=0.02) and the relative hazard of an unfavorable outcome (a combined end point) was 20.1 (P=0.003), as compared with patients in the two other flow groups. Specifically, all four patients who died from heart failure and three of five who died suddenly were in this subgroup. CONCLUSIONS: In patients with hypertrophic cardiomyopathy, the degree of microvascular dysfunction is a strong, independent predictor of clinical deterioration and death. Severe microvascular dysfunction is often present in patients with mild or no symptoms and may precede clinical deterioration by years.

Maximum left ventricular thickness and risk of sudden death in patients with hypertrophic cardiomyopathy.

OBJECTIVES: We sought to assess the relationship between maximum left ventricular (LV) wall thickness and outcome in patients with hypertrophic cardiomyopathy (HCM). BACKGROUND: An association between maximum LV wall thickness and risk of sudden death was suggested in HCM. This finding requires further investigation, given the important implications for risk stratification and treatment. METHODS: We analyzed the mortality and risk profile of 237 patients (age 41 +/- 17 years; 63% male) classified into five groups based on echocardiographic maximum LV thickness. RESULTS: During follow-up (12 +/- 7 years), 36 patients died of cardiovascular causes, including 16 sudden deaths. Maximum LV thickness was not associated with a risk of sudden death (p = 0.37) nor with overall cardiovascular mortality (p = 0.7). With the exception of the small subset with thickness values < or =15 mm, with a consistently benign clinical course, the distribution of sudden death and overall cardiovascular mortality was not significantly different among the other four classes, ranging from 16 to 19 mm to > or =30 mm. Among 30 patients with extreme LV thickness (> or =30 mm), only one sudden event occurred among six patients diagnosed at <18 years of age (17%) and none among 24 diagnosed at > or =18 years of age. The prevalence of nonsustained ventricular tachycardia, syncope, an abnormal blood pressure response to exercise, and atrial fibrillation was similar among the five thickness classes. CONCLUSIONS: During 12-year follow-up, we observed no association between maximum LV thickness and cardiovascular mortality in a community-based population with HCM. The degree of maximum LV wall thickness should be considered in the context of a multifactorial approach to risk stratification, rather than as an isolated risk factor. Only in those patients diagnosed at a very young age might the presence of extreme LV wall thickness represent, per se, a potential marker of risk of sudden death.

Registro Absorb Italiano (BVS-RAI): an investigators-owned and -directed, open, prospective registry of consecutive patients treated with the Absorb™ BVS: study design.

BACKGROUND: The Absorb™ BVS is a bioresorbable, everolimus-eluting scaffold approved and marketed for coronary use. Published data on long-term results after treatment are limited to a small number of patients, most of them with elective PCI of simple lesions. The importance of scaffold resorption is variably appreciated among cardiologists, and indications for use from health technology assessment bodies or guidelines are missing. Instruments are needed to collect, share and assess the experience being accumulated with this new device in several centres. METHODS/DESIGN: The BVS-RAI Registry is a spontaneous initiative of a group of Italian interventional cardiologists in cooperation with Centro di Ricerche Farmacologiche e Biomediche "Mario Negri" Institute, and is not recipient of funding or benefits originating from the BVS manufacturer. It is a prospective registry with 5-year follow-up of all consecutive patients who have undergone successful implantation of 1 or more coronary BVS following the indications, techniques and protocols used in each of the participating institutions. Outcome measures are BVS target lesion failure within one year and device-oriented major adverse cardiac events within 5years. The registry started in October 2012 and will extend enrolment throughout 2015, with the aim to include about 1000 patients. ClinicalTrials.gov identifier is CT02298413. CONCLUSIONS: The BVS-RAI Registry will contribute observational knowledge on the long-term safety and efficacy of the Absorb™ BVS as used in a number of Italian interventional centres in a broad spectrum of settings. Unrewarded and undirected consecutive patient enrolments are key-features of this observation, which is therefore likely to reflect common clinical practice in those centres.

[Right ventricular involvement in hypertrophic cardiomyopathy. A case report and brief review of the literature]. / Coinvolgimento del ventricolo destro nella cardiomiopatia ipertrofica. Presentazione di un caso clinico e breve revisione della letteratura.

A clinical case of non-obstructive hypertrophic cardiomyopathy with involvement of the right ventricle is reported. The patient was a 42-year-old male with symptoms suggesting an effort angina of recent onset. The diagnosis was established by echocardiography, which showed asymmetric hypertrophy of the interventricular septum (20 mm), hypertrophy of the right ventricular free wall, and severe hypertrophy of the septal papillary muscle of the tricuspid valve. The patient underwent a complete diagnostic evaluation, including exercise stress test, Holter monitoring, magnetic resonance, myocardial tomoscintigraphy and complete hemodynamic assessment. Medical treatment with atenolol 50 mg day was started; at 1-year follow-up the patient's clinical conditions are good, with decrease of anginal episodes. The literature review elicits the paucity of information about this condition, despite a frequent involvement of both ventricles in hypertrophic obstructive cardiomyopathy. The case reported shows two atypical aspects: a) the involvement of the right ventricle in non-obstructive hypertrophic cardiomyopathy is anecdotal; b) this pattern of hypertrophy (right ventricular free wall/septal papillary muscle) has never been previously reported. Right ventricular involvement in patients with hypertrophic cardiomyopathy must be carefully investigated, because it may be more frequent than conventionally deemed.

Impact of early abciximab administration on infarct size in patients with ST-elevation myocardial infarction.

BACKGROUND: Early abciximab administration in patients requiring transportation to undergo primary percutaneous coronary intervention (PPCI) has been reported to improve clinical outcome. We aimed to verify whether early administration leads to reduced infarct size (IS), assessed by delayed-enhancement magnetic resonance imaging (DE-MRI). METHODS: We randomized 110 patients with acute myocardial infarction with symptom-to-diagnosis time <6h to either early (55 patients) or late (55 patients) abciximab administration. DE-MRI was performed at 4 days and 6 months. The primary end point was IS at 6 months. Secondary end points were the rate of ST-segment elevation resolution ≥ 50% (STR) at 60 min after PPCI, the extent of microvascular obstruction at 4 days, and the change in IS and transmurality at 6 months vs. 4 days. RESULTS: DE-MRI was performed in 103 patients after 4 days, and in 87 at 6 months. The mean IS at 6 months was 13.8 ± 9.0% in the early vs. 13.0 ± 9.9% in the Late group (P>0.2). Similarly, microvascular obstruction and the change in IS were not significantly different. The Early group showed a significantly higher STR (94.5% vs. 80.0%, P=0.04) and a larger reduction in infarct transmurality (-9.2 ± 7.0% vs. -5.9 ± 6.4%; P=0.03), while a larger reduction in IS was observed only in patients with ECG-to-Cath Lab time >60 min. CONCLUSIONS: Early abciximab administration did not lead to a smaller IS at 6-month DE-MRI, and was associated with a significant reduction in IS and transmurality only in patients with longer transportation time, warranting further investigation in this patient subset.

Usefulness of intravascular ultrasound in a case of angiographically unapparent myocardial bridging.

A patient with an acute coronary syndrome underwent coronary angiography, which showed only a moderate stenosis in the mid portion of the left anterior descending artery. Intravascular ultrasound was performed for a better assessment of the lesion, and surprisingly, it showed a myocardial bridge over the narrowed segment, which was unapparent at angiography. In fact, the systolic compression of the artery was very limited, and no 'step down-step up' course was recognized. Given the absence of significant atherosclerosis in the intramyocardial and adjacent segments, and considering the poor results reported for stenting of tunnelled coronary arteries, we decided to treat the patient medically. At 6-month follow-up, the patient is asymptomatic and has no inducible ischemia.In conclusion, this case shows how intravascular ultrasound can be useful in patients with an unclear angiographic diagnosis for a better patient management.

Emergency coronary artery bypass grafting in patients with acute myocardial infarction treated with glycoprotein IIb/IIIa receptor inhibitors.

Glycoprotein (GP) IIb/IIIa receptor inhibitors before primary angioplasty in patients with ST-elevation acute myocardial infarction (STEMI) are recommended by current guidelines. Thus, an increasing number of patients receive these drugs before coronary angiography, particularly if a between-hospital transfer is needed. However, when coronary anatomy is unsuitable for angioplasty, emergency coronary artery bypass grafting (CABG) under GP IIb/IIIa inhibitor treatment may be needed, with a potential increase in bleeding risk. Abciximab has a long duration of action, because of its high-affinity binding to GP IIb/IIIa receptors. Initial retrospective studies reported a higher incidence of major bleeding during emergency CABG after abciximab administration, leading to the recommendation of delaying surgery >12 h. However, data from the prospective trials on abciximab do not confirm the increase in bleeding risk, and current evidence shows that emergency surgery can be performed safely soon after abciximab cessation. Monitoring of activated clotting time during surgery and platelet transfusion in case of postoperative relevant bleeding are the only measures needed. No data are available on emergency surgery in patients with STEMI treated with eptifibatide or tirofiban. However, their short-lasting effects and the results of trials on non-ST-elevation acute coronary syndromes suggest that they could even reduce postoperative bleeding by preventing platelet consumption during cardiopulmonary bypass. In conclusion, the early administration of GP IIb/IIIa inhibitors, in particular of abciximab, in patients with STEMI in whom primary angioplasty is planned should not be discouraged because of the potential bleeding risk in case of emergency CABG.

Randomized comparison of sirolimus and paclitaxel drug-eluting stents for long lesions in the left anterior descending artery: an intravascular ultrasound study.

OBJECTIVES: The goal of this work was to verify whether the superiority of the sirolimus-eluting stent (SES) in inhibiting neointimal hyperplasia could be demonstrated in complex coronary lesions. BACKGROUND: Both the SES (Cypher, Cordis, Miami Lakes, Florida) and the paclitaxel-eluting stent (PES) (Taxus, Boston Scientific, Natick, Massachusetts) have shown a marked reduction in neointimal hyperplasia compared with bare-metal stents. Intravascular ultrasound (IVUS) is the best method to assess arterial response to stent deployment, but few IVUS data are available comparing complex lesions treated with SES or PES. METHODS: We prospectively randomized patients with complex lesions to SES or PES implantation. Intravascular ultrasound and quantitative angiography were performed post-procedure and at 9 months. Mean neointimal hyperplasia area (NIHA), percent of NIHA (NIHA%), mean peristent plaque area (PSPA), and percent of PSPA (PSPA%) were calculated. The primary end point was NIHA% at follow-up. Secondary end points included change in PSPA% and angiographic late luminal loss at follow-up. RESULTS: Of the 100 patients enrolled, 42 receiving the SES and 43 receiving the PES had adequate IVUS assessment. Vessel, plaque, and lumen areas were comparable at follow-up, but NIHA% was significantly lower with SES than PES (7.4 +/- 4.2% vs. 15.4 +/- 8.1%; p < 0.001). A significant reduction in PSPA% was observed with SES (-4 +/- 10% vs. 0 +/- 8%; p = 0.01). Late loss was significantly lower with SES (0.16 +/- 0.19 mm vs. 0.32 +/- 0.33 mm; p = 0.003). CONCLUSIONS: The SES shows a significantly higher inhibition of neointimal hyperplasia compared with PES in complex lesions. However, both stents have excellent IVUS and angiographic results at 9 months. A significant reduction in peri-stent plaque is observed only with SES.

Relevance of coronary microvascular flow impairment to long-term remodeling and systolic dysfunction in hypertrophic cardiomyopathy.

OBJECTIVES: 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.