Effect of late sodium current inhibition on MRI measured diastolic dysfunction in aortic stenosis: a pilot study

Beyond hypertension: Diastolic dysfunction associated with cancer treatment in the era of cardio-oncology

Cancer patients are at an increased risk of cardiovascular events. Both old-generation cytostatics/cytotoxics and new-generation "targeted" drugs can in fact damage cardiomyocytes, endothelial cells of veins and arteries, specialized cells of the conduction system, pericardium, and valves. A new discipline, cardio-oncology, has therefore developed with the aim of protecting cancer patients from cardiovascular events, while also providing them with the best possible oncologic treatment. Anthracyclines have long been known to elicit cardiotoxicity that, depending on treatment- or patient-related factors, may progress with a variable velocity toward cardiomyopathy and systolic heart failure. However, early compromise of diastolic function may precede systolic dysfunction, and a progression of early diastolic dysfunction to diastolic rather than systolic heart failure has been documented in long-term cancer survivors. This chapter first describes general notions about hypertension in the cancer patient and then moves on reviewing the pathophysiology and clinical trajectories of diastolic dysfunction, and the molecular mechanisms of anthracycline-induced diastolic dysfunction. Diastolic dysfunction can in fact be caused and/or aggravated by hypertension. Pharmacologic foundations and therapeutic opportunities to prevent or treat diastolic dysfunction before it progresses toward heart failure are also reviewed, with a special emphasis on the mechanisms of action of drugs that raised hopes to treat diastolic dysfunction in the general population (sacubitril/valsartan, guanylyl cyclase activators, phosphodiesterase inhibitors, ranolazine, inhibitors of type-2 sodium-glucose-inked transporter). Cardio-oncologists will be confronted with the risk:benefit ratio of using these drugs in the cancer patient.

Left Ventricular Diastolic Function Studied with Magnetic Resonance Imaging: A Systematic Review of Techniques and Relation to Established Measures of Diastolic Function

Purpose: In recent years, cardiac magnetic resonance (CMR) has been used to assess LV diastolic function. In this systematic review, studies were identified where CMR parameters had been evaluated in healthy and/or patient groups with proven diastolic dysfunction or known to develop heart failure with preserved ejection fraction. We aimed at describing the parameters most often used, thresholds where possible, and correlation to echocardiographic and invasive measurements. Methods and results: A systematic literature review was performed using the databases of PubMed, Embase, and Cochrane. In total, 3808 articles were screened, and 102 studies were included. Four main CMR techniques were identified: tagging; time/volume curves; mitral inflow quantification with velocity-encoded phase-contrast sequences; and feature tracking. Techniques were described and estimates were presented in tables. From published studies, peak change of torsion shear angle versus volume changes in early diastole (−dφ′/dV′) (from tagging analysis), early peak filling rate indexed to LV end-diastolic volume <2.1 s⁻¹ (from LV time-volume curve analysis), enlarged LA maximal volume >52 mL/m², lowered LA total (<40%), and lowered LA passive emptying fractions (<16%) seem to be reliable measures of LV diastolic dysfunction. Feature tracking, especially of the atrium, shows promise but is still a novel technique. Conclusion: CMR techniques of LV untwisting and early filling and LA measures of poor emptying are promising for the diagnosis of LV filling impairment, but further research in long-term follow-up studies is needed to assess the ability for the parameters to predict patient related outcomes.

Myocardial tissue deformation is reduced in subjects with coronary microvascular dysfunction but not rescued by treatment with ranolazine

BACKGROUND

Patients with coronary microvascular dysfunction (CMD) often have diastolic dysfunction, representing an important therapeutic target. Ranolazine-a late sodium current inhibitor-improves diastolic function in animal models and subjects with obstructive coronary artery disease (CAD).

HYPOTHESIS

We hypothesized that ranolazine would beneficially alter diastolic function in CMD.

METHODS

To test this hypothesis, we performed retrospective tissue tracking analysis to evaluate systolic/diastolic strain, using cardiac magnetic resonance imaging cine images acquired in a recently completed, randomized, double-blind, placebo-controlled, crossover trial of short-term ranolazine in subjects with CMD and from 43 healthy reference controls.

RESULTS

Diastolic strain rate was impaired in CMD vs controls (circumferential diastolic strain rate: 99.9% ± 2.5%/s vs 120.1% ± 4.0%/s, P = 0.0003; radial diastolic strain rate: -199.5% ± 5.5%/s vs -243.1% ± 9.6%/s, P = 0.0008, case vs control). Moreover, peak systolic circumferential strain (CS) and radial strain (RS) were also impaired in cases vs controls (CS: -18.8% ± 0.3% vs -20.7% ± 0.3%; RS: 35.8% ± 0.7% vs 41.4% ± 0.9%; respectively; both P < 0.0001), despite similar and preserved ejection fraction. In contrast to our hypothesis, however, we observed no significant changes in left ventricular diastolic function in CMD cases after 2 weeks of ranolazine vs placebo.

CONCLUSIONS

The case-control comparison both confirms and extends our prior observations of diastolic dysfunction in CMD. That CMD cases were also found to have subclinical systolic dysfunction is a novel finding, highlighting the utility of this retrospective approach. In contrast to previous studies in obstructive CAD, ranolazine did not improve diastolic function in CMD.

Role of Ranolazine in cardiovascular disease and diabetes: Exploring beyond angina

Ranolazine was FDA approved for chronic angina in 2006. Since then, there has been extensive research involving this drug. The mechanism of action, debatable at the time of approval, has been demonstrated. Ranolazine acts via inhibition of late sodium channel current in the myocardium. This acts by lowering abnormally high cytosolic calcium levels. Other possible clinical applications of Ranolazine have also been explored. Out of many lines of investigation, its effects in atrial fibrillation, especially post-CABG and recurrent atrial fibrillation show promise. It has also shown definite HbA1c lowering effects when used in diabetics with coronary artery disease. Other possible indications for the drug include pulmonary arterial hypertension, diastolic dysfunction and chemotherapy-induced cardiotoxicity. This review aims to summarize major research regarding Ranolazine in potential applications beyond chronic angina. There are few dedicated large, randomized, phase III trials exploring the newer effects of Ranolazine. There are a few such trials underway, but more are needed.