Viktor Hamrefors

Soluble Urokinase Plasminogen Activator Receptor: A Risk Factor for Carotid Plaque, Stroke, and Coronary Artery Disease

Background and Purpose— Recent studies indicate that the urokinase system could have an important role in atherogenesis and plaque rupture. The relationships among the soluble urokinase plasminogen activator receptor (suPAR), carotid plaque, and incidence of ischemic stroke and coronary artery disease (CAD) events were studied in a prospective cohort. Methods— Occurrence of carotid plaque and plasma levels of suPAR were assessed in 5166 men and women, aged 45 to 68 years, participating in the Malmö Diet and Cancer study. Incidences of ischemic stroke and CAD were monitored during a mean follow-up of 15 years. Results— Subjects with carotid plaque had significantly higher levels of suPAR compared with those without carotid plaque. suPAR was associated with increased incidence of ischemic stroke (hazard ratio [HR] for third versus first tertile, 1.50; 95% confidence interval [CI], 1.06–2.11) and CAD (HR, 1.55; 95% CI, 1.13–2.13) after adjustment for risk factors. The risk factor–adjusted HR for ischemic stroke was 2.21 (95% CI, 1.52–3.22) in subjects with carotid plaque and high suPAR (ie, third tertile) and 1.51 (95% CI, 1.05–2.17) in subjects with carotid plaque and low suPAR compared with those without carotid plaque and low suPAR (reference). High levels of suPAR significantly increased the risk of ischemic stroke and CAD in subjects with carotid plaque. Conclusions— suPAR is associated with increased occurrence of carotid plaque and increased incidence of ischemic stroke and CAD. Presence of both elevated levels of suPAR and carotid plaque increases the risk of ischemic stroke in an additive way.

A gene score of nine LDL and HDL regulating genes is associated with fluvastatin-induced cholesterol changes in women

While conventional pharmacogenetic studies have considered single gene effects, we tested if a genetic score of nine LDL- and HDL-associated single nucleotide polymorphisms, previously shown to predict cardiovascular disease, is related to fluvastatin-induced lipid change. In patients with asymptomatic plaque in the right carotid artery, thus candidates for statin therapy, we related score LDL [APOB(rs693), APOE(rs4420638), HMGCR(rs12654264), LDLR(rs1529729), and PCSK9(rs11591147)] and score HDL [ABCA1(rs3890182), CETP(rs1800775), LIPC(rs1800588), and LPL(rs328)] as well as the combined score LDL+HDL to fluvastatin-induced LDL reduction (± metoprolol) (n = 395) and HDL increase (n = 187) following 1 year of fluvastatin treatment. In women, an increasing number of unfavorable alleles (i.e., alleles conferring higher LDL and lower HDL) of score LDL+HDL (P = 0.037) and of score LDL (P = 0.023) was associated with less pronounced fluvastatin-induced LDL reduction. Furthermore, in women, both score LDL+HDL (P = 0.001) and score HDL (P = 0.022) were directly correlated with more pronounced fluvastatin-induced HDL increase, explaining 5.9–11.6% of the variance in treatment response in women. There were no such associations in men. This suggests that a gene score based on variation in nine different LDL- and HDL-associated genes is of importance for the magnitude of fluvastatin HDL increase in women with asymptomatic plaque in the carotid artery.

Smoking Modifies the Associated Increased Risk of Future Cardiovascular Disease by Genetic Variation on Chromosome 9p21

Aims Genetic predisposition for cardiovascular disease (CVD) is likely to be modified by environmental exposures. We tested if the associated risk of CVD and CVD-mortality by the single nucleotide polymorphism rs4977574 on chromosome 9p21 is modified by life-style factors. Methods and results A total of 24944 middle-aged subjects (62% females) from the population-based Malmö-Diet-and-Cancer-Cohort were genotyped. Smoking, education and physical activity-levels were recorded. Subjects were followed for 15 years for incidence of coronary artery disease (CAD; N = 2309), ischemic stroke (N = 1253) and CVD-mortality (N = 1156). Multiplicative interactions between rs4977574 and life-style factors on endpoints were tested in Cox-regression-models. We observed an interaction between rs4977574 and smoking on incident CAD (P = 0.035) and CVD-mortality (P = 0.012). The hazard ratios (HR) per risk allele of rs4977574 were highest in never smokers (N = 9642) for CAD (HR = 1.26; 95% CI 1.13–1.40; P<0.001) and for CVD-mortality (HR = 1.40; 95% CI 1.20–1.63; P<0.001), whereas the risk increase by rs4977574 was attenuated in current smokers (N = 7000) for both CAD (HR = 1.05; 95%CI 0.95–1.16; P = 0.326) and CVD-mortality (HR = 1.08; 95%CI 0.94–1.23; P = 0.270). A meta-analysis supported the finding that the associated increased risk of CAD by the risk-allele was attenuated in smokers. Neither education nor physical activity-levels modified the associated risk of CAD, ischemic stroke and CVD mortality conferred by rs4977574. Conclusion Smoking may modify the associated risk of CAD and CVD-mortality conferred by genetic variation on chromosome 9p21. Whether the observed attenuation of the genetic risk reflects a pathophysiological mechanism or is a result of smoking being such a strong risk-factor that it may eliminate the associated genetic effect, requires further investigation.

A myocardial infarction genetic risk score is associated with markers of carotid atherosclerosis

Abstract.  Hamrefors V, Hedblad B, Engström G, Almgren P, Sjögren M, Melander O (Lund University, Malmö, Sweden). A myocardial infarction genetic risk score is associated with markers of carotid atherosclerosis. J Intern Med 2012; 271: 271–281.

Gene variance in the nicotinic receptor cluster (CHRNA5‐CHRNA3‐CHRNB4) predicts death from cardiopulmonary disease and cancer in smokers

Genetic variation in the cluster on chromosome 15, encoding the nicotinic acetylcholine receptor subunits (CHRNA5‐CHRNA3‐CHRNB4), has shown strong associations with tobacco consumption and an additional risk increase in smoking‐related diseases such as chronic obstructive pulmonary disease (COPD), peripheral artery disease and lung cancer.

Pharmacogenetic implications for eight common blood pressure-associated single-nucleotide polymorphisms.

Objective: We aimed to test whether eight common recently identified single-nucleotide polymorphisms (SNPs), strongly associated with blood pressure (BP) in the population, also have impact on the degree of BP reduction by antihypertensive agents with different mechanisms. Methods: In 3863 Swedish hypertensive patients, we related number of unfavorable alleles of each SNP (i.e. alleles associated with higher baseline BP) to the magnitude of BP reduction during 6 months of monotherapy with either a beta-blocker, a thiazide diuretic or diltiazem. Results: For six SNPs (rs16998073, rs1378942, rs3184504, rs1530440, rs16948048, rs17367504) no pharmacogenetic interactions were suggested, whereas two SNPs showed nominal evidence of association with treatment response: PLCD3-rs12946454 associated with more SBP (beta = 1.53 mmHg per unfavorable allele; P = 0.010) and DBP (beta = 0.73 mmHg per unfavorable allele; P = 0.014) reduction in patients treated with diltiazem, in contrast to those treated with beta-blockers or diuretics wherein no treatment response association was found. CYP17A1-rs11191548 associated with less DBP reduction (beta = −1.26 mmHg per unfavorable allele; P = 0.018) in patients treated with beta-blockers or diuretics, whereas there was no treatment response association in diltiazem-treated patients. However, if accounting for multiple testing, the significant associations for rs12946454 and rs11191548 were attenuated. Conclusion: For a majority of these, eight recently identified BP-associated SNPs, there are probably no important pharmacogenetic interactions for BP reduction with use of beta-blockers, diuretics or diltiazem. Whether the nominally significant associations for rs12946454 and rs11191548 are true signals and could be of possible clinical relevance for deciding treatment of polygenic essential hypertension should be further tested.

Common genetic risk factors for coronary artery disease: new opportunities for prevention?

Atherosclerotic cardiovascular disease (CVD) is a leading cause of mortality and morbidity worldwide, with coronary artery disease (CAD) being the single leading cause of death. Better control of risk factors, enhanced diagnostic techniques and improved medical therapies have all substantially decreased the mortality of CAD in developed countries. However, CAD and other forms of atherosclerotic CVD are projected to remain the leading cause of death by 2030 and we face a number of challenges if the outcomes of CAD are to be further improved. The fact that a substantial fraction of high‐risk subjects do not reach treatment goals for important risk factors is one of these challenges. At the same time, there is also a non‐negotiable fraction of ‘concealed’ high‐risk subjects who are not detected by current risk algorithms and diagnostic modalities. In recent years, we have started to rapidly increase our knowledge of the framework of common genetics underlying CAD and atherosclerotic CVD in the population. In conjunction with modern diagnostic and therapeutic options, this new genetic knowledge may provide a valuable tool for further improvements in prevention. This review summarizes the recent findings from the search for common genetic risk factors for CAD. Furthermore, the author discusses how such recent findings could potentially be used in a number of clinical applications within CAD prevention, including in clinical risk stratification, in prediction of drug treatment response and in the search for targets for novel preventive therapies.

Orthostatic Hypotension and Elevated Resting Heart Rate Predict Low-Energy Fractures in the Population: The Malmö Preventive Project.

Background Autonomic disorders of the cardiovascular system, such as orthostatic hypotension and elevated resting heart rate, predict mortality and cardiovascular events in the population. Low-energy-fractures constitute a substantial clinical problem that may represent an additional risk related to such autonomic dysfunction. Aims To test the association between orthostatic hypotension, resting heart rate and incidence of low-energy-fractures in the general population. Methods and Results Using multivariable-adjusted Cox regression models we investigated the association between orthostatic blood pressure response, resting heart rate and first incident low-energy-fracture in a population-based, middle-aged cohort of 33 000 individuals over 25 years follow-up. The median follow-up time from baseline to first incident fracture among the subjects that experienced a low energy fracture was 15.0 years. A 10 mmHg orthostatic decrease in systolic blood pressure at baseline was associated with 5% increased risk of low-energy-fractures (95% confidence interval 1.01–1.10) during follow-up, whereas the resting heart rate predicted low-energy-fractures with an effect size of 8% increased risk per 10 beats-per-minute (1.05–1.12), independently of the orthostatic response. Subjects with a resting heart rate exceeding 68 beats-per-minute had 18% (1.10–1.26) increased risk of low-energy-fractures during follow-up compared with subjects with a resting heart rate below 68 beats-per-minute. When combining the orthostatic response and resting heart rate, there was a 30% risk increase (1.08–1.57) of low-energy-fractures between the extremes, i.e. between subjects in the fourth compared with the first quartiles of both resting heart rate and systolic blood pressure-decrease. Conclusion Orthostatic blood pressure decline and elevated resting heart rate independently predict low-energy fractures in a middle-aged population. These two measures of subclinical cardiovascular dysautonomia may herald increased risks many years in advance, even if symptoms may not be detectable. Although the effect sizes are moderate, the easily accessible clinical parameters of orthostatic blood pressure response and resting heart rate deserve consideration as new risk predictors to yield more accurate decisions on primary prevention of low-energy fractures.

Markers of cardiovascular autonomic dysfunction predict COPD in middle-aged subjects

Autonomic dysfunction is commonly observed in chronic obstructive pulmonary disease (COPD) and may relate to the known comorbidity with coronary artery disease (CAD). We hypothesised that clinical markers of cardiovascular autonomic dysfunction predict COPD in the population, independently of CAD. In a population-based cohort of 24 768 subjects (mean age 45 years) without baseline airflow obstruction, we analysed the cross-sectional relationship of one-minute orthostatic systolic blood pressure (SBP) and diastolic blood pressure (DBP) changes and resting heart rate with forced vital capacity (FVC) and forced expiratory volume in 1 s (FEV1). Cox regression models were used to analyse the association of orthostatic SBP and DBP changes (SBP/DBP decrease) and resting heart rate with incident COPD over a 32-year follow-up. Baseline orthostatic SBP decrease (p=0.020) and DBP decrease (p=0.001) were associated with reduced FVC, whereas resting heart rate was associated with reduced FVC and FEV1 (p<0.001). After adjustment for smoking and baseline lung function, SBP decrease predicted COPD (hazard ratio (HR) 1.10 per 10 mmHg, 95% CI 1.03–1.18). Resting heart rate predicted COPD among smokers (HR 1.11 per 10 beats-per-minute increase, 95% CI 1.05–1.18). Results were similar in subjects without CAD. Subtle signs of cardiovascular autonomic dysfunction may precede the development of COPD in middle-aged subjects. This association is independent of the relationship between cardiovascular autonomic dysfunction and CAD. Clinical markers of subtle cardiovascular autonomic dysfunction predict incident COPD in a middle-aged population http://ow.ly/J93J30i0O4s

Monitoring of cerebral oximetry during head-up tilt test in adults with history of syncope and orthostatic intolerance

Aims We applied near-infrared-spectroscopy (NIRS) to measure absolute frontal cerebral tissue oxygen saturation (SctO2) during head-up tilt test (HUT) in patients investigated for unexplained syncope. Methods and results Synchronized non-invasive beat-to-beat haemodynamic monitoring, ECG, SctO2 (NIRS; normal range: 60-80%), and peripheral oxygen saturation (left hand, SpO2) were applied during HUT in a random sample of patients with unexplained syncope. Tracings of 54 patients (mean-age: 55 ± 19 years, 39% male) with negative HUT, vasovagal syncope (VVS), or orthostatic hypotension (OH) were analysed. In 44 patients HUT was diagnostic, in 10 HUT was negative. Thirty-one experienced VVS. Of these, 6 had spontaneous and 25 nitroglycerin-induced syncope. Thirteen patients had orthostatic hypotension (OH). Although there was no significant change in mean-arterial pressure from baseline to 1 min before syncope or end of passive HUT phase (-1.4 ± 13.9 mmHg; P = 0.45), there was a significant fall in SctO2 during the same period (-3.2 ± 3.2%; P ≤ 0.001). Among patients who experienced syncope, a decrease in SctO2 from 71 ± 5% at baseline to 53 ± 9% (P < 0.001) at syncope was observed. During HUT, there was a significant difference in delta SctO2 between spontaneous VVS (-4.5 ± 3.0%) and negative HUT (-1.3 ± 1.9%; P  = 0.021), but not between spontaneous VVS and OH (-5.4 ± 4.2%; P = 0.65). In spontaneous VVS, progressive decrease of SctO2 was independent of mean arterial pressure decrease (P  = 0.22). Conclusions Progressive decrease in cerebral tissue oxygenation independent of mean-arterial pressure may precede spontaneous vasovagal reflex during tilt. Patients experience syncope when SctO2 falls below 60%. These data confirm clinical utility of absolute cerebral oximetry monitoring for syncope investigation. We applied NIRS to measure frontal cerebral tissue oxygen saturation (SctO2) during head-up tilt test (HUT) in patients with unexplained syncope. In 44 of 54 patients, HUT was diagnostic. In patients with syncope, a significant SctO2-decrease was observed. Different patterns of SctO2 can be detected.