Kalyanasundaram Venkataraman

Cardiovascular risk factors in hematopoietic cell transplantation survivors: role in development of subsequent cardiovascular disease

Hematopoietic cell transplantation (HCT) recipients may be at an increased risk of developing hypertension, diabetes, and dyslipidemia (referred to as cardiovascular risk factors [CVRFs]); and these factors can potentially increase the risk of cardiovascular disease (CVD). We examined the incidence and predictors of CVRFs and subsequent CVD in 1885 consecutive 1+year survivors of HCT performed at City of Hope between 1995 and 2004. Ten-year cumulative incidence of hypertension, diabetes, dyslipidemia, and multiple (≥ 2) CVRFs was 37.7%, 18.1%, 46.7%, and 31.4%, respectively. The prevalence of CVRFs was significantly higher among HCT recipients compared with the general population; contributed to largely by allogeneic HCT recipients. Older age and obesity at HCT were associated with increased risk of CVRFs. History of grade II-IV acute graft versus host disease was associated with an increased risk for hypertension (relative risk [RR] = 9.1, P < .01), diabetes (RR = 5.8, P < .01), and dyslipidemia (RR = 3.2, P < .01); conditioning with total body irradiation was associated with an increased risk of diabetes (RR = 1.5, P = .01) and dyslipidemia (RR = 1.4, P < .01). There was an incremental increase in 10-year incidence of CVD by number of CVRFs (4.7% [none], 7.0% [1 CVRF], 11.2% [≥ 2 CVRFs], P < .01); the risk was especially high (15.0%) in patients with multiple CVRFs and pre-HCT exposure to anthracyclines or chest radiation.

Hysteresis in the Human RR-QT Relationship During Exercise and Recovery

The present study was undertaken to test the hypothesis that the human RR‐QT relationship during dynamic exercise diners markedly from that during the recovery phase. Fourteen subjects from the age of 16 to 71 years exercised on a treadmill according to the Bruce protocol. Electrocardiograms were recorded continuously on a magnetic tape, from 1 minute before exercise to 10 minutes into recovery. An exponential formula, proposed by us earlier, closely represented the exercise RR‐QT data. However, it was not appropriate for the often S‐shaped recovery curves which invariably deviated from the exercise curves, exhibiting hysteresis. Initially, all recovery QT intervals were shorter than the exercise values, but later in the recovery, some crossed the exercise curves from below, resulting in longer QT intervals. The recovery data were fitted by a third degree polynomial, and the hysteresis was calculated as the area between the exercise and recovery curves within a 150 ms range of the RR interval starting from its minimum value. The mechanisms for the occurrence of hysteresis are likely to involve the sympatho‐adrenal activity in the early post‐exercise period and the time course of QT interval adaptation to rapid changes in the RR interval.

Circadian rhythmicity of heart rate and QTc interval in diabetic autonomic neuropathy : implications for the mechanism of sudden death

Patients with diabetic autonomic neuropathy (DAN) exhibit decreased heart rate variability (HRV) and are prone to sudden death. When HRV was used as an index of DAN, the circadian rhythmicity of heart rate and QT intervals was studied in 17 patients with diabetes who had varying degrees of DAN and 13 healthy control subjects. Heart rate and QT and QTc intervals for all subjects were found to exhibit a significant circadian periodicity. Heart rate was lowest and QT and QTc intervals were longest between midnight and 6:00 AM; heart rate increased and QT and QTc intervals shortened in the hours after waking. The diabetic group with more severe autonomic neuropathy (DAN+, HRV = 76 +/- 20 msec, n = 7) had significantly higher heart rate and shorter QT and QTc intervals compared with the diabetic group without autonomic neuropathy (DAN-, HRV = 120 +/- 13 msec, n = 10) or healthy control subjects (CT, HRV = 119 +/- 26 msec, n = 13). Twenty-four-hour mean heart rate was 90 +/- 7 beats/min (range, 79 to 98 beats/min) for DAN+, 77 +/- 8 beats/min (range, 64 to 86 beats/min) for DAN- (DAN+ vs DAN-; p = 0.005), and 74 +/- 7 beats/min (range, 64 to 80 beats/min) for CT (DAN+ vs CT; p = 0.0004). Mean 24-hour QTc was 391 +/- 13 msec (range, 387 to 399) msec for DAN+, 417 +/- 19 msec (range, 413 to 425 msec) for DAN- (DAN+ vs DAN-; p = 0.01), and 412 +/- 28 msec (range, 408 to 419 msec) for CT (DAN+ vs CT; p = 0.09).(ABSTRACT TRUNCATED AT 250 WORDS)

Diltiazem as monotherapy for systemic hypertension: A multicenter, randomized, placebo-controlled trial☆

A multicenter, randomized, placebo-controlled, parallel group study of diltiazem in essential hypertension was carried out in 77 patients (40 diltiazem, 37 placebo) with stable supine diastolic blood pressure (BP) between 95 and 110 mm Hg. Patients were withdrawn from previous antihypertensive therapy for at least 4 weeks, titrated to the optimal dose, and followed for a total of 12 weeks during therapy. A diltiazem dose of 360 mg/day was required in 85% of the patients. Average BP in all positions was significantly (p less than 0.0001) reduced by diltiazem compared with placebo. With diltiazem, average supine BP fell from 156/100 mm Hg at baseline to 141/87 at end titration and 145/90 mm Hg at week 12, whereas average standing BP fell from 152/101 mm Hg to 136/90 and 143/91 mm Hg, respectively, at those times. There was no significant change in heart rate at week 12. Diltiazem tended to be more effective in older patients, but caused no increase in orthostatic BP drop. There were no statistically significant changes in BP in the placebo group. Two patients receiving placebo and 1 patient receiving diltiazem discontinued therapy as a result of adverse effects, and overall, side effects were only slightly more common with diltiazem treatment. Thus, diltiazem was effective and well tolerated single therapy for mild to moderate systemic hypertension and appears to compare favorably to most agents being used.

Incidence and predictors of congestive heart failure after autologous hematopoietic cell transplantation

Advances in autologous hematopoietic cell transplantation (HCT) strategies have resulted in a growing number of long-term survivors. However, these survivors are at increased risk of developing cardiovascular complications due to pre-HCT therapeutic exposures and conditioning and post-HCT comorbidities. We examined the incidence and predictors of congestive heart failure (CHF) in 1244 patients undergoing autologous HCT for a hematologic malignancy between 1988 and 2002. The cumulative incidence of CHF was 4.8% at 5 years and increased to 9.1% at 15 years after transplantation; the CI for female lymphoma survivors was 14.5% at 15 years. The cohort was at a 4.5-fold increased risk of CHF (standardized incidence ratio = 4.5), compared with the general population. The risk of CHF increased substantially for patients receiving ≥ 250 mg/m(2) of cumulative anthracycline exposure (odds ratio [OR]: 9.9, P < .01), creating a new and lower threshold for cardiac surveillance after HCT. The presence of hypertension among recipients of high-dose anthracycline (≥ 250 mg/m(2)) resulted in a 35-fold risk (OR: 35.3, P < .01) of CHF; the risk was nearly 27-fold (OR: 26.8, P < .01) for high-dose anthracycline recipients with diabetes, providing evidence that hypertension and diabetes may be critical modifiers of anthracycline-related myocardial injury after HCT and creating targeted populations for aggressive intervention.

Genetic susceptibility to anthracycline-related congestive heart failure in survivors of haematopoietic cell transplantation.

Haematopoietic cell transplantation (HCT) survivors are at increased risk for developing congestive heart failure (CHF), primarily due to pre‐HCT exposure to anthracyclines. We examined the association between the development of CHF after HCT and polymorphisms in 16 candidate genes involved in anthracycline metabolism, iron homeostasis, anti‐oxidant defence, and myocardial remodelling. A nested case‐control study design was used. Cases (post‐HCT CHF) were identified from 2950 patients who underwent HCT between 1988 and 2007 at City of Hope and had survived ≥1 year. This cohort formed the sampling frame for selecting controls (without CHF) matched on: age, race/ethnicity, cumulative anthracycline exposure, stem cell source (allogeneic, autologous), and length of follow‐up. Seventy‐seven cases with pre‐HCT germline DNA and 178 controls were genotyped. Multivariate analysis revealed that the odds of CHF was higher in females [Odds Ratio (OR) = 2·9, P < 0·01], individuals with pre‐HCT chest radiation (OR = 4·7, P = 0·05), hypertension (OR = 2·9, P = 0·01), and with variants of genes coding for the NAD(P)H‐oxidase subunit RAC2 (rs13058338, 7508T→A; OR = 2·8, P < 0·01), HFE (rs1799945, 63C→G; OR = 2·5, P = 0·05) or the doxorubicin efflux transporter ABCC2 (rs8187710, 1515G→A; OR = 4·3, P < 0·01). A combined (clinical and genetic) CHF predictive model performed better [area under the curve (AUC), 0·79] than the genetic (AUC = 0·67) or the clinical (AUC = 0·69) models alone.

Effect of propranolol on the QT intervals of normal individuals during exercise: a new method for studying interventions.

A new method was used to study the effect of a single dose of propranolol on the QT intervals during exercise in 11 normal volunteers. They exercised maximally on a bicycle ergometer and repeated the test after taking propranolol (40 mg) by mouth two hours before. Electrocardiograms were continuously recorded on magnetic tape and the cardiac cycle length (RR interval) and the QT interval were measured every five seconds by a computer aided method. The RR-QT data from each test during the exercise phase were analysed by an exponential formula, QT = A - B x exp (-k x RR) and by Bazetts formula, QT = K x square root of (RR). Three reference QT intervals, QTc1, QTc2, and QTc3, estimated at RR = 400, 700, and 1000 ms respectively from the regression curves of both formulas were compared. The exponential formula, which consistently gave a better fit with the data, showed that propranolol had a biphasic action on the QT intervals during exercise. It significantly prolonged the mean (SD) interval at longer cycle lengths (from 287 (27) to 305 (18) ms at RR = 1000 ms and shortened it at shorter cycle lengths (from 198 (14) to 179 (16) ms at RR = 400 ms). In contrast, Bazetts formula did not show any significant effect when the same raw data were used. The exponential formula can be adapted to study other interventions or conditions that affect QT intervals.

Screening for cardiac dysfunction in anthracycline-exposed childhood cancer survivors.

Purpose: To examine the utility and reliability of obtaining early echocardiographic measurements of left ventricular (LV) remodeling as well as blood biomarkers of cardiac injury in asymptomatic childhood cancer survivors at risk for LV dysfunction and congestive heart failure due to past exposure to anthracycline chemotherapy. Experimental Design: Using a cross-sectional design, anthracycline-exposed childhood cancer survivors with preserved ejection fraction (EF; ≥50%) were evaluated using early echocardiographic indices and blood biomarkers of LV dysfunction. Survivors treated with ≥300 mg/m2 anthracyclines [high risk (HR): n = 100] were compared with those treated with <300 mg/m2 anthracyclines [low risk (LR): n = 50] and matched healthy controls (HC: n = 50). All echocardiograms were interpreted by an institutional cardiologist and a study cardiologist blinded to risk status. Results: Time from diagnosis was comparable for HR (12.0 years) and LR (13.2 years, P = 0.8) survivors. Echocardiograms: HR had lower LV thickness-dimension ratio (Z-score: HR: −0.62, LR: −0.03, HC: −0.02; P < 0.001), increased LV wall stress (HR: 66.7 g/cm2, LR: 56.6 g/cm2, HC: 54.2 g/cm2; P < 0.01), and higher myocardial performance index (HR: 0.51, LR: 0.46, HC: 0.46; P < 0.01). Interobserver correlation (clinical/blinded reading) for all echocardiographic indices was excellent (range: R = 0.76–0.97, P < 0.001). Blood biomarkers: With the exception of NT-proBNP (r = 0.28, P < 0.01), there was no correlation between blood biomarkers (B-type natriuretic peptide, Troponin-T, ST-2, Galectin-3) and LV dysfunction. Conclusion: Childhood cancer survivors with preserved EF 10+ years from anthracycline exposure had dose-dependent changes in echocardiographic markers of LV dysfunction. Clin Cancer Res; 20(24); 6314–23. ©2014 AACR.

Role of Oxidative Stress in Amiodarone-induced Toxicity

Background: The clinical usefulness of amiodarone for the treatment of cardiac arrhythmias is limited by multiorgan toxicity, especially pulmonary and hepatic. There are conflicting reports in the literature regarding the role of free radicals in the initiation of amiodarone- induced toxicity. We evaluated the possible oxidative stress in a chronic model that is known to manifest pulmonary toxicity. Methods and Results: A group of 20 Fischer-344 rats were injected with 60 mg/kg/day of amiodarone for 21 days. A control group of 20 animals received only saline injections. The alveolar macrophages obtained by lung lavage were incubated with hydroethidine and opsonized green fluorescent zymosan particles to measure oxidative and phagocytic activities by flow cytometry. Malondialdehyde levels were measured to assess the extent of lipid per oxidation in lung, liver, spleen, kidney, and heart. Total phospholipid levels in all the col lected tissues and distribution of phospholipid classes in the lung and the liver were mea sured. The levels of amiodarone and its metabolite desethylamiodarone in serum and all collected tissues were measured by high-performance liquid chromatography. The phago cytic activity of the macrophages from treated animals was decreased by 18-22% (P < .03) compared to controls; however, the oxidative activities of control and treated groups were not significantly different. The tissue malondialdehyde levels were not significantly different except in the spleen where they increased after amiodarone treatment (18.2 ± 1.1 vs 23.7 ± 2.8 μM/g tissue, P < .0001). Malondyaldehyde levels were not significantly different when normalized to lipid phosphorous content. Lung, liver, and spleen showed significantly higher phospholipid levels in the treated group. The tissue amiodarone and desethylamiodarone lev els in the treated group were highest in spleen followed by lung, liver, kidney, and heart. Conclusions: The results show that amiodarone-induced pulmonary and hepatic toxicity is not directly mediated by oxidative stress; however, increased lipid peroxidation in the spleen, although secondary to phospholipidosis, may be physiologically significant.

Carnitine and Cardiac Dysfunction in Childhood Cancer Survivors Treated with Anthracyclines

Childhood cancer survivors are at high risk of developing congestive heart failure (CHF) compared with the general population, and there is a dose-dependent increase in CHF risk by anthracycline dose. The mechanism by which this occurs has not been fully elucidated. Metabolomics, the comprehensive profile of small-molecule metabolites, has the potential to provide insight into the pathogenesis of disease states and discover diagnostic markers for therapeutic targets. We performed echocardiographic testing and blood plasma metabolomic analyses (8 pathways; 354 metabolites) in 150 asymptomatic childhood cancer survivors previously treated with anthracyclines. Median time from cancer diagnosis to study participation was 12.4 years (2.6–37.9 years); 64% were treated for a hematologic malignancy; median anthracycline dose was 350 mg/m2 (25–642 mg/m2). Thirty-five (23%) participants had cardiac dysfunction—defined as left ventricular end-systolic wall stress >2SD by echocardiogram. Plasma levels of 15 compounds in three metabolic pathways (carbohydrate, amino acid, and lipid metabolism) were significantly different between individuals with cardiac dysfunction and those with normal systolic function. After adjusting for multiple comparisons, individuals with cardiac dysfunction had significantly lower plasma carnitine levels [relative ratio (RR), 0.89; P < 0.01] in relation to those with normal systolic function. These findings may facilitate the development of primary prevention (treatment of carnitine deficiency before/during anthracycline administration) and secondary prevention strategies (screening and treatment in long-term survivors) in patients at highest risk for CHF. Cancer Epidemiol Biomarkers Prev; 23(6); 1109–14. ©2014 AACR.