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Gianfranco Piccirillo,
Damiano Magrì,
Sabrina Matera, Marzia Magnanti,
Eleonora Pasquazzi,
Erika Schifano,
Stefania Velitti,
Marilena Mitra,
Vincenzo Marigliano,
Marino Paroli,
Andrea Ghiselli
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ABSTRACT: Recent evidence shows that pink grapefruit juice, which is a recommended dietary addition that contains high amounts of the antioxidant flavonoid naringenin, prolongs the corrected QT (QT(c)), a noninvasive electrophysiological marker of spatial myocardial repolarization, and does so by inhibiting the rapid component of the delayed rectifier K+ current (I(Kr)). Prompted by the observation that all class III antiarrhythmic drugs inhibit this current, thereby sometimes provoking torsades de pointes, we compared the effects of a liter of freshly squeezed pink grapefruit juice with those of 2 commonly used class III antiarrhythmics amiodarone and sotalol on the major noninvasive markers of temporal variability in myocardial repolarization used to stratify the risk of sudden death from malignant ventricular arrhythmias. In 32 subjects, 10 with postischemic dilated cardiomyopathy, 12 with hypertensive cardiomyopathy, and 10 healthy, we assessed QT(c) and QT variability index (QTVI) after administration of fresh pink grapefruit juice, placebo, amiodarone, or sotalol. After pink grapefruit juice and sotalol, all these indexes increased significantly from values observed after placebo (P<0.05) and from values after amiodarone (P<0.05). Conversely, after amiodarone, QT(c), but not QTVI, increased significantly from values after placebo (P<0.05). Presumably because of its high naringenin glycoside content, pink grapefruit juice prolongs cardiac repolarization and concurrently increases temporal cardiac repolarization dispersion. The potential proarrhythmic actions of pink grapefruit juice might be of concern in patients with major myocardial structural disorders.
Translational Research 05/2008; 151(5):267-72. · 2.99 Impact Factor
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Damiano Magrì,
Susanna Sciomer,
Francesco Fedele,
Gianfranco Gualdi,
Emanuele Casciani,
Pellegrina Pugliese,
Anna Losardo,
Giancarlo Ferrazza,
Eleonora Pasquazzi,
Erika Schifano, Marzia Magnanti,
Sabrina Matera,
Vincenzo Marigliano,
Gianfranco Piccirillo
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ABSTRACT: Despite recent progress in iron chelation therapy, sudden cardiac death due to malignant ventricular arrhythmias remains a vexing, clinical problem in patients with beta-thalassemia major (TM). In this study we assessed whether the major indices of QT variability, emerging tools for risk stratification of sudden cardiac death, differ in young asymptomatic patients with TM and healthy persons.
Thirty patients with TM and 30 healthy control subjects underwent a 5-min electrocardiography recording to calculate the following variables: QT variance (QT(v)), QT(v) normalized for mean QT (QTVN) and QT variability index (QTVI). All subjects also underwent a two-dimensional and Doppler echocardiography study and magnetic resonance imaging (MRI) to determine cardiac and hepatic T2* values.
No differences were observed in clinical and conventional echo-Doppler findings in healthy control subjects and patients with TM whereas QT(v), QTVN and QTVI values were significantly higher in patients than those in controls (QT(v), P < 0.001; QTVN, P < 0.05 and QTVI, P < 0.001) and cardiac T2* and hepatic MRI T2* values were significantly lower in patients with TM (P < 0.001). The indices of temporal QT variability correlated significantly with MRI data.
Young asymptomatic patients with TM have increased cardiac repolarization variability as assessed by QT variability indices, probably due to cardiac iron deposition. These easily assessed, non-invasive markers could be used to identify increased myocardial repolarization lability early in asymptomatic patients with TM.
European Journal Of Haematology 10/2007; 79(4):322-9. · 2.61 Impact Factor
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Gianfranco Piccirillo,
Damiano Magrì,
Sabrina Matera, Marzia Magnanti,
Alessia Torrini,
Eleonora Pasquazzi,
Erika Schifano,
Stefania Velitti,
Vincenzo Marigliano,
Raffaele Quaglione,
Francesco Barillà
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ABSTRACT: The most widely accepted marker for stratifying the risk of sudden cardiac death (SCD) in post myocardial infarction patients is a depressed left ventricular function. Left ventricular ejection fractions (EF) of 35% or less increase the risk of sudden death but values between 35 and 40% raise concern. The underlying pathophysiological mechanism is sustained ventricular tachycardia or fibrillation, both associated with increased cardiac repolarization variability. We assessed whether the indices of QT variability from a short-term electrocardiographic (ECG) recording predict sudden death.
A total of 396 subjects with chronic heart failure (CHF) due to post-ischaemic cardiomyopathy, with an EF between 35 and 40% and in NYHA class I, underwent a 5 min ECG recording to calculate the following variables: QT variance (QT(v)), QT normalized for the square of the mean QT (QTVN), and QT variability index (QTVI). Corrected QT (QT(c)) was calculated from a 12-lead ECG recording. All participants were followed for 5 years. A multivariable survival model indicated that a QTVI greater than or equal to the 80th percentile indicated a high risk of SCD [hazards ratio (HR) 4.6, 95% confidence interval (CI) 1.5-13.4, P = 0.006] and, though to a lesser extent, a high risk of total mortality (HR 2.4, 95% CI 1.2-4.9, P = 0.017). The model including QTVI as a continuous variable confirmed a similar high risk for SCD (HR 2.9, 95% CI 1.3-6.5, P = 0.01) and for total mortality (HR 2.6, 95% CI 1.3-5.2, P = 0.008).
Although asymptomatic patients with CHF who have a slightly depressed EF are at low risk of sudden death, the category is extraordinarily numerous. The QTVI could be helpful in stratifying the risk of sudden death in this otherwise undertreated population.
European Heart Journal 07/2007; 28(11):1344-50. · 10.48 Impact Factor
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Gianfranco Piccirillo,
Damiano Magrì,
Silvia di Carlo,
Tiziana De Laurentis,
Alessia Torrini,
Sabrina Matera, Marzia Magnanti,
Leda Bernardi,
Franco Barillà,
Raffaele Quaglione,
Evaristo Ettorre,
Vincenzo Marigliano
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ABSTRACT: Several studies have shown that cardiac-resynchronization therapy (CRT) improves haemodynamic function, cardiac symptoms, and heart rate variability (HRV) and reduces the risk of mortality and sudden death in subjects with chronic heart failure (CHF). In subjects with CHF, power spectral values for the low-frequency (LF) component of RR variability < or =13 ms2, are associated with an increased risk of sudden death.
To assess whether spectral indexes obtained by power spectral analysis of HRV and systolic blood pressure (SBP) variability could predict malignant ventricular arrhythmias in patients with severe CHF treated with an implantable cardioverter-defibrillator (ICD) alone or with ICD+CRT. In addition, changes in non-invasive spectral indices using short-term power spectral analysis of HRV and SBP variability during controlled breathing in 15 patients with CHF treated with an ICD alone and 16 patients receiving ICD+CRT, were assessed pre-treatment and at 1 year.
Arrhythmias necessitating an appropriate ICD shock were more frequent in subjects who had low LF power. CRT improved all spectral components, including LF power.
Low LF power values predict an increased risk of malignant ventricular arrhythmias; after 1 year of CRT most non-spectral and spectral data, including LF power, improved. Whether these improvements lead to better long-term survival in patients with CHF remains unclear.
European Journal of Heart Failure 12/2006; 8(7):716-22. · 4.90 Impact Factor
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ABSTRACT: The QT variability index (QTVI) indicates temporal dispersion in myocardial repolarization, and a high QTVI is associated with a propensity for sudden death from malignant ventricular arrhythmias in subjects at high risk. In this study, the authors assessed the effects of free breathing, controlled breathing, and sympathetic stress (tilt) on the QTVI in patients with chronic heart failure (CHF) and healthy control subjects. The authors also examined the influence of age on the same variables. To obtain normative data, they calculated 95% confidence intervals for healthy subjects grouped according to age. Under all experimental conditions, the QTVI was larger in the CHF group overall and in the age subsets than in controls. In patients and controls, the QTVI increased significantly during tilt, although no differences were found between the QTVI measured during free and controlled breathing. In healthy controls, the following variables correlated significantly with the QTVI: age and baseline heart rate (P < 0.001). In patients with CHF, aging had no influence on the QTVI. Conclusion: Age, sympathetic stress, and CHF all tend to increase the QTVI and could potentially induce sudden death. Further studies should assess the usefulness of the QTVI as a marker predicting sudden cardiac death under the various conditions of risk.
Translational Research 08/2006; 148(2):72-8. · 2.99 Impact Factor
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ABSTRACT: In patients with refractory neurally mediated syncope, tilt training--standing motionless against a wall for increased periods of time per day over one month--can often eliminate recurrent episodes and reduce presyncopal symptoms. We designed dual retrospective and prospective studies to assess cardiovascular autonomic function in subjects with recurrent syncope and identify the most effective length of tilt training between one and three months.
In the retrospective study, before tilt training, and in the prospective study, before and after training, all subjects underwent a recording for short-term spectral analysis of heart rate and systolic blood pressure variability. Before tilt-training, autonomic nervous system function differs in patients with recurrent neurally mediated syncope who respond to tilt training for one month and those who do not. "Responders", patients experiencing no episodes of syncope during the 12-month follow-up, had higher low-frequency power of RR (LF(RR)) (p < 0.05) and LF(RR) in normalized units (NU) (p < 0.001) and lower high-frequency power (HF(RR)) (p < 0.05) and HF(RR)NU (p < 0.001) than "non-responders", patients reporting at least one syncopal episode during the 12-month follow-up. In the retrospective study, no difference was found between spectral data for "non-responders" with positive responses to tilt test with and without nitro derivatives. Prolonging tilt-training to three months increased the number of responders (late-responders) by 80% (p < 0.001) and power spectral analysis of heart rate variability (HRV) before tilt training can identify late-responders by their low LF(RR)NUs (<40) and high HF(RR)Nus (>60). Furthermore in late-responders, tilt training brings about a change in cardiovascular autonomic function: at 3 months, LF(RR)NUs increase and HF(RR)NU diminish.
Power spectral analysis of HRV seems to be a useful tool to preselect patients who are most likely to benefit from prolonged therapy, thus increasing compliance.
International Journal of Cardiology 08/2006; 111(1):59-66. · 7.08 Impact Factor
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Gianfranco Piccirillo,
Giuseppe Germanò,
Antonio Vitarelli,
Maddalena Ragazzo,
Silvia di Carlo,
Tiziana De Laurentis,
Alessia Torrini,
Sabrina Matera, Marzia Magnanti,
Nicola Marchitto,
Livia Bonanni,
Damiano Magrì
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ABSTRACT: Early hypertension is associated with left ventricular diastolic dysfunction due to increased end-diastolic pressure. This increase, through the cardiopulmonary reflexes, can influence autonomic cardiovascular control.
We assessed autonomic nervous system modulation of cardiovascular signals by power spectral analysis of RR interval and systolic arterial pressure variabilities in subjects with recently diagnosed hypertension with or without diastolic dysfunction and in normotensive control subjects.
Both hypertensive groups had higher low-frequency (LF) power expressed in normalized units (NUs) than normotensive controls (p < 0.05; p < 0.001) during controlled breathing at rest. The LF spectral index measured after tilt was greater in hypertensive subjects with diastolic dysfunction than in those without (p < 0.05). LF NUs measured at rest correlated significantly with the E/A wave ratio and after tilt with the E-wave deceleration time.
These results seem to indicate that in subjects with recently diagnosed hypertension sympathetic modulation of the sinus node prevails. During tilt, a maneuver designed to stimulate systemic arterial and cardiopulmonary baroreceptor reflexes, hypertensive subjects with diastolic dysfunction, who presumably also have higher end-diastolic pressures, seem to have greater sympathetic modulation of the sinus node than hypertensive subjects without diastolic dysfunction.
International Journal of Cardiology 07/2006; 110(2):160-6. · 7.08 Impact Factor
