Safety profile and utility of treadmill exercise in patients with high-gradient hypertrophic cardiomyopathy.

BACKGROUND: Exercise echocardiography in the evaluation of hypertrophic cardiomyopathy (HCM) provides valuable information for risk stratification, selection of optimal treatment, and prognostication. However, HCM patients with left ventricular outflow tract gradients ≥30mm Hg are often excluded from exercise testing because of safety considerations. We examined the safety and utility of exercise testing in patients with high-gradient HCM. METHODS: We evaluated clinical characteristics, hemodynamics, and imaging variables in 499 consecutive patients with HCM who performed 959 exercise tests. Patients were divided based on peak left ventricular outflow tract gradients using a 30-mm Hg threshold into the following: obstructive (n=152), labile-obstructive (n=178), and nonobstructive (n=169) groups. RESULTS: There were no deaths during exercise testing. We noted 20 complications (2.1% of tests) including 3 serious ventricular arrhythmias (0.3% of tests). There was no difference in complication rate between groups. Patients with obstructive HCM had a higher frequency of abnormal blood pressure response (obstructive: 53% vs labile: obstructive: 41% and nonobstructive: 37%; P=.008). Obstructive patients also displayed a lower work capacity (obstructive: 8.4±3.4 vs labile obstructive: 10.9±4.2 and nonobstructive: 10.2±4.0, metabolic equivalent; P<.001). Exercise testing provided incremental information regarding sudden cardiac death risk in 19% of patients with high-gradient HCM, and we found a poor correlation between patient-reported functional class and work capacity. CONCLUSION: Our results suggest that exercise testing in HCM is safe, and serious adverse events are rare. Although numbers are limited, exercise testing in high-gradient HCM appears to confer no significant additional safety hazard in our selected cohort and could potentially provide valuable information.

Ambrisentan and Tadalafil Up-front Combination Therapy in Scleroderma-associated Pulmonary Arterial Hypertension.

BACKGROUND: Scleroderma-associated pulmonary arterial hypertension (SSc-PAH) is a rare disease characterized by a very dismal response to therapy and poor survival. We assessed the effects of up-front combination PAH therapy in patients with SSc-PAH. METHODS: In this prospective, multicenter, open-label trial, 24 treatment-naive patients with SSc-PAH received ambrisentan 10 mg and tadalafil 40 mg daily for 36 weeks. Functional, hemodynamic, and imaging (cardiac magnetic resonance imaging and echocardiography) assessments at baseline and 36 weeks included changes in right ventricular (RV) mass and pulmonary vascular resistance as co-primary endpoints and stroke volume/pulmonary pulse pressure ratio, tricuspid annular plane systolic excursion, 6-minute walk distance, and N-terminal pro-brain natriuretic peptide as secondary endpoints. RESULTS: At 36 weeks, we found that treatment had resulted in significant reductions in median (interquartile range [IQR]) RV mass (28.0 g [IQR, 20.6-32.9] vs. 32.5 g [IQR, 23.2-41.4]; P < 0.05) and median pulmonary vascular resistance (3.1 Wood units [IQR, 2.0-5.7] vs. 6.9 Wood units [IQR, 4.0-12.9]; P < 0.0001) and in improvements in median stroke volume/pulmonary pulse pressure ratio (2.6 ml/mm Hg [IQR, 1.8-3.5] vs. 1.4 ml/mm Hg [IQR 8.9-2.4]; P < 0.0001) and mean ( ± SD) tricuspid annular plane systolic excursion (2.2 ± 0.12 cm vs. 1.65 ± 0.11 cm; P < 0.0001), 6-minute walk distance (395 ± 99 m vs. 343 ± 131 m; P = 0.001), and serum N-terminal pro-brain natriuretic peptide (647 ± 1,127 pg/ml vs. 1,578 ± 2,647 pg/ml; P < 0.05). CONCLUSIONS: Up-front combination therapy with ambrisentan and tadalafil significantly improved hemodynamics, RV structure and function, and functional status in treatment-naive patients with SSc-PAH and may represent a very effective therapy for this patient population. In addition, we identified novel hemodynamic and imaging biomarkers that could have potential value in future clinical trials. Clinical trial registered with www.clinicaltrials.gov (NCT01042158).

Comparison of Outcomes in Patients With Nonobstructive, Labile-Obstructive, and Chronically Obstructive Hypertrophic Cardiomyopathy.

Patients with nonobstructive hypertrophic cardiomyopathy (HC) are considered low risk, generally not requiring aggressive intervention. However, nonobstructive and labile-obstructive HC have been traditionally classified together, and it is unknown if these 2 subgroups have distinct risk profiles. We compared cardiovascular outcomes in 293 patients HC (96 nonobstructive, 114 labile-obstructive, and 83 obstructive) referred for exercise echocardiography and magnetic resonance imaging and followed for 3.3 ± 3.6 years. A subgroup (34 nonobstructive, 28 labile-obstructive, 21 obstructive) underwent positron emission tomography. The mean number of sudden cardiac death risk factors was similar among groups (nonobstructive: 1.4 vs labile-obstructive: 1.2 vs obstructive: 1.4 risk factors, p = 0.2). Prevalence of late gadolinium enhancement (LGE) was similar across groups but more non-obstructive patients had late gadolinium enhancement ≥20% of myocardial mass (23 [30%] vs 19 [18%] labile-obstructive and 8 [11%] obstructive, p = 0.01]. Fewer labile-obstructive patients had regional positron emission tomography perfusion abnormalities (12 [46%] vs nonobstructive 30 [81%] and obstructive 17 [85%], p = 0.003]. During follow-up, 60 events were recorded (36 ventricular tachycardia/ventricular fibrillation, including 30 defibrillator discharges, 12 heart failure worsening, and 2 deaths). Nonobstructive patients were at greater risk of VT/VF at follow-up, compared to labile obstructive (hazed ratio 0.18, 95% confidence interval 0.04 to 0.84, p = 0.03) and the risk persisted after adjusting for age, gender, syncope, family history of sudden cardiac death, abnormal blood pressure response, and septum ≥3 cm (p = 0.04). Appropriate defibrillator discharges were more frequent in nonobstructive (8 [18%]) compared to labile-obstructive (0 [0%], p = 0.02) patients. In conclusion, nonobstructive hemodynamics is associated with more pronounced fibrosis and ischemia than labile-obstructive and is an independent predictor of VT/VF in HC.

Brief low-workload myocardial ischaemia induces protection against exercise-related increase of platelet reactivity in patients with coronary artery disease.

OBJECTIVE: In patients with acute myocardial infarction, pre-infarction angina is associated with smaller infarct size, probably mainly through myocardial protection induced by ischaemic preconditioning. However, in models of recurrent thrombosis myocardial ischaemia also improves arterial patency. This study investigated whether myocardial ischaemia has any effect on platelet function in patients with coronary artery disease. PATIENTS AND DESIGN: Twenty patients with low-workload myocardial ischaemia underwent, in a randomised crossover study, two treadmill exercise stress tests (EST) on two separate days: a single maximal EST (EST-1) and a maximal EST (EST-2) performed 45 minutes after a low-workload EST stopped at 1-mm ST depression (p-EST). Platelet reactivity was evaluated by measuring the closure time in response to ADP/collagen by the PFA-100 method, and monocyte-platelet aggregate (MPA) formation and CD41 platelet expression, with and without ADP stimulation, by flow cytometry. RESULTS: Compared to resting values, closure time decreased at peak EST-1 (p<0.001) but not at peak EST-2. MPA after ADP stimulation increased more significantly at peak EST-1 compared with peak EST-2 (p<0.001). Repetition in seven patients of the pEST/EST-2 protocol after intravenous administration of the adenosine antagonist theophylline showed prevention of the effects of p-EST on exercise-induced platelet reactivity. CONCLUSIONS: A short episode of myocardial ischaemia induces protection against an exercise-induced increase of platelet reactivity. These data also suggest a role for adenosine in this phenomenon.

[Mechanisms of myocardial cell protection from ischemia/reperfusion injury and potential clinical implications]. / Meccanismi di protezione delle cellule miocardiche dal danno da ischemia/riperfusione e potenziali implicazioni terapeutiche.

Myocardial cell damage caused by myocardial ischemia results from several factors that include the duration of ischemia, oxygen demand by cardiomyocytes at the time of ischemia, and the presence and entity of collateral blood flow to the ischemic area. Importantly, myocardial cell injury may derive not only from ischemia itself but also from detrimental phenomena occurring during the restoration of myocardial blood flow after the ischemic episode (reperfusion damage). In the last decades a lot of studies have demonstrated that cardiomyocytes have several mechanisms that provide them protection against the damage deriving from ischemia-reperfusion, also allowing a prolongation of survival in the most severe cases. In this article we review some of these mechanisms, also discussing their present and/or potential therapeutic applications in the clinical setting. The topics include the interventions aimed at reducing cardiac work through a reduction of oxygen demand by myocardial cells or at optimizing the utilization of energetic resources by myocardial cells in situations of ischemia, the importance of phenomena such as ischemic preconditioning (early and delayed) and postconditioning of myocardial cells, and, finally, the theoretic possibility of interventions aimed at preventing cell death consequent to apoptosis.

Predictors of exercise-induced platelet reactivity in patients with chronic stable angina.

OBJECTIVE: Previous studies have shown that exercise increases platelet reactivity in patients with coronary artery disease (CAD). However, the response of platelet reactivity to exercise is considerably variable and its predictors are poorly known. METHODS: We studied 214 consecutive patients (age 61.9 +/- 9 years, 167 men) with stable angina and obstructive coronary artery disease. All patients underwent a symptom-limited treadmill exercise stress test. Venous blood samples were collected before and at peak exercise. Platelet reactivity was assessed by the platelet function analyzer system as the time for flowing whole blood to occlude a collagen-adenosine diphosphate ring (closure time: shorter times = higher reactivity). Both closure time at peak exercise and the exercise-induced change in closure time from rest were assessed as an expression of exercise-related platelet reactivity. RESULTS: Closure time decreased significantly with exercise in the whole population (from 95.9 +/- 22 to 81.2 +/- 18 s, P < 0.001). The only variable significantly associated with closure time at peak exercise was hematocrit (P = 0.003). Basal systolic blood pressure (P = 0.023) and lack of nitrate use (P = 0.03), on the contrary, were the only variables significantly associated with increased exercise-induced closure time change. Peak hematocrit maintained an independent association with peak closure time in multivariable analysis, although the correlation was mild. No variable, on the contrary, was associated with exercise-induced platelet reactivity after correction for basal closure time values at multivariable analyses. CONCLUSION: Among stable coronary artery disease patients, platelet reactivity after exercise cannot be reliably predicted by several common clinical and laboratory variables.